Session EA: CEU Poster Session - 2:00 - 3:48PM

Reconstructing $\pi^0$ Decays at Intermediate Energy Using the MPC-EX Detector at RHIC-PHENIX

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory produces $\pi^0$s that decay into the majority of photons detected by the Pioneering High Energy Nuclear Interaction eXperiment (PHENIX). The Muon Piston Calorimeter (MPC) in PHENIX is a PbWO4 electromagnetic calorimeter situated at forward rapidity (3<$|\eta|$<4). The preshower MPC-EX is a Si-W extension to the MPC that detects the decay photon shower position with higher spatial resolution than the MPC. The lowest energy $\pi^0$s decay into photons that are separated in the MPC while the highest energy $\pi^0$s decay to photons that are reconstructed as a single electromagnetic shower. At intermediate energies, both can happen and fluctuations in the showers are larger than at higher energies. Care must be taken to reconstruct $\pi^0$s at these energies. We will show the current status of the analysis of intermediate energy $\pi^0$s in $\sqrt{s_{NN}} = 200$ GeV d+Au collisions.   

Building a Test Stand for Silicon Photomultiplies for sPHENIX Calorimeter Readout

The sPHENIX detector is a second-generation heavy ion collision experiment planned to be built at Brookhaven National Laboratory's (BNL) Relativistic Heavy Ion Collider (RHIC). The read-out of the electromagnetic and hadronic calorimeters will be via silicon photomultipliers (SiPMs). In preparation for characterizing the approximately 125,000 SiPMs that will be used in the detector, a test stand has been built at Augustana University. In this poster we give the details of the test stand and example tests that have and can be done.   

Revisiting Cuts for Improved Calibrations of the PHENIX Muon Piston Calorimeter

The PHENIX Muon Piston Calorimeter (MPC) has been used extensively to study RHIC p+p and d+Au collisions, but has not been used as often in the analysis of Au+Au collisions. Forward/backward measurements of transverse energy $\left(3.1<\mid\eta\mid<3.9\right)$ in the beam energy scan are of particular interest for studies of the strongly interacting quark-gluon plasma. Now that new methods are being employed to help calibrate the heavy ion collisions, focus can again be put on the optimal set of cuts for calibrating these runs. Studies leading to the determination of these cuts will be described.   

Jet Reconstruction at the PHENIX Experiment for Studying Proton Structure

Jets in hadronic collisions are useful probes to access hard-scattered parton kinematics without involving fragmentation functions to particular hadrons. Jet reconstruction using the anti-k$_{\mathrm{t}}$ sequential recombination method has recently become an effective analysis tool in the PHENIX experiment at the Relativistic Heavy Ion Collider at Brookhaven National Lab. Use of the method in the limited acceptance PHENIX detector was verified by good agreement between perturbative QCD predictions and jet yields for $p+p$ collisions from 2008 data; the $p+p$ jet yields were then compared with jet production in $d+$\textit{Au} collisions. Jet measurements are also of interest in polarized $p+p$ collisions to study spin-momentum correlations in the proton independent of fragmentation functions. We implement the jet reconstruction method for the 2015 detector setup applied to simulated $p+p$ data for future use in real data analysis.   

A Study on Double Event Detection for PHENIX at RHIC

Many measurements made in Heavy Ion experiments such as PHENIX at RHIC focus on geometrical properties because phenomena such as collective flow give insight into quark-gluon plasma and the strong nuclear force. As part of this investigation, PHENIX has taken data in 2016 for deuteron on gold collisions at several energies. An acceptable luminosity is achieved by injecting up to 120 separate bunches each with billions of ions into the storage ring, from which two, separate beams are made to collide. This method has a drawback as there is a chance for multiple pairs of nuclei to collide in a single bunch crossing. Data taken in a double event cannot be separated into two independent events and has no clear interpretation. This effect's magnitude is estimated and incorporated in published results as a systematic uncertainty and studies on this topic have already been conducted within PHENIX. I develop several additional algorithms to flag multiple interaction events by examining the time dependence of data from the two Beam-Beam Counters -- detectors surrounding the beam pipe on opposite ends of the interaction region. The algorithms are tested with data, in which events with double interactions are artificially produced using low luminosity data.   

Silicon Photomultiplier Characterization for sPHENIX Calorimeters

Silicon photomultipliers (SiPMs) are preferable to photomultiplier tubes due to their small size, insensitivity to magnetic fields, low operating voltage, and capability of detecting single photons. The sPHENIX collaboration at RHIC will use SiPMs in their proposed electromagnetic and hadronic calorimeters. The University of Michigan is assembling and implementing a test stand to characterize the dark count rate, temperature dependence, gain, and photon detection efficiency of SiPMs. To more accurately determine the dark count rate, we have constructed a light tight box to isolate the SiPM, which surrounds an electronics enclosure that protects the SiPM circuitry, and installed software to record the output signals. With this system, we will begin to collect data and optimize the system to test arrays of SiPMs instead of single devices as the proposed calorimeters will require testing approximately 115,000 SiPMs.   

Tungsten and Scintillating Fiber Electromagnetic Calorimeter for sPHENIX

Utilizing the products of relativistic heavy ion collisions, one can shed light on the physics behind the earliest stages of the universe. Consisted of unbounded quarks and gluons, the Quark Gluon Plasma (QGP) results from the collisions of heavy ions. The use of electromagnetic and hadronic calorimetry is an option for studying the strong interactions which govern the QGP. The sPHENIX detector is planned for use at the Relativistic Heavy Ion Collider (RHIC) which detects jets from the collisions of large nuclei. The sPHENIX EMCal will consist of a tungsten absorber and scintillating fibers and will be read out with silicon photomultipliers. Made up of many individual towers, the EMCal covers full $\phi$ and large $\eta$. We will discuss the production process of these towers as well as the projectivity of the towers. Towers projective in one dimension ($\phi$) have been produced and tested in beam at Fermilab. We will present recent developments in the first two dimensionally projective towers and future plans.   

Single Cluster $\pi^0$ Reconstruction at High Energy Using the MPC-EX Detector at RHIC-PHENIX

Most photons produced in collisions at the Relativistic Heavy Ion Collider (RHIC) at Brookehaven National Laboratory (BNL) originate from the decay of $\pi^0$ mesons. The Pioneering High Energy Nuclear Interaction eXperiment (PHENIX) is a versatile detector and it is capable of detecting photons with energy >40 GeV at forward rapidity using the Muon Piston Calorimeter (MPC). At these high energies the photons decay with such a small opening angle that the MPC cannot resolve the two photons, but the two photons can be still be disambiguated in the MPC-Extension (MPC-EX), a Si-W preshower detector. An algorithm that detects the photon peaks and calculates their opening angle has been developed. Using knowledge of the opening angle, total energy of the shower and asymmetry, it is possible to reconstruct the mass of the $\pi^0$. We will show the current state of the high energy $\pi^0$ analysis in d+Au collisions.   

Nuclear structure studies of $^{\mathrm{202}}$Hg and $^{\mathrm{203}}$Tl using deep-inelastic collisions

Nuclei with a few valence nucleons outside $^{\mathrm{208}}$Pb are crucial for testing the nuclear shell model and guiding our understanding of single particle structure. Data in this region are also potentially relevant to nuclear astrophysics. This analysis focused on the high-spin structure of $^{\mathrm{202}}$Hg and $^{\mathrm{203}}$Tl. Excited states in these nuclei were populated through deep-inelastic reactions from a beam of $^{\mathrm{136}}$Xe and that was incident on a thick target of $^{\mathrm{208}}$Pb in the Gammasphere array at Argonne National Laboratory. The level schemes of $^{\mathrm{202}}$Hg and $^{\mathrm{203}}$Tl were extended by locating a new isomer in each nucleus and a number of new high-spin states built on top of the isomers. The newly-observed states will be discussed in the context of the shell model.   

Search for Chiral Magnetic Effect with Identified Particles in Au+Au Collisions at $\sqrt{s_{NN}}$ = 39 GeV from RHIC/STAR

Chirality imbalance could occur in local domains inside the hot nuclear matter formed in high-energy heavy-ion collisions. In the presence of a strong magnetic field, this chirality imbalance will induce an electric charge separation along the magnetic field direction, owing to the chiral magnetic effect (CME) [1]. Previous azimuthal-angle correlation measurements [2] with unidentified charged particles have manifested charge separation signals consistent with the predictions of the CME. But the magnitudes of the background contributions have not been understood. In this poster, we present the correlation results with identified particles (protons and pions) using STAR data of 39 GeV Au+Au collisions. The results will be compared with those from Au+Au at $\sqrt{s_{NN}}$ = 200 GeV, as well as the published results of unidentified particles at $\sqrt{s_{NN}}$ = 39 GeV. References [1]D. Kharzeev, Phys. Lett. B \textbf{633} (2006) 260. [2]L. Adamczyk et al., Phys. Rev. Lett. \textbf{113} (2014) 052302.   

Double-Spin Asymmetry in Neutral Pion ($\pi^0$) Production in Longitudinally Polarized $p+p$ Collisions

Beyond the valence quarks' spin contribution to the total spin of a proton, gluon and sea quark contributions are becoming clear as well. For proton+proton collisions at a center of mass energy of 510 GeV, neutral pion production is dominated by gluon-gluon and gluon-quark scattering. An avenue to constrain the gluon polarization is the asymmetry, $A_{LL}$, in the production of neutral pions from collisions of longitudinally spin-polarized proton beams. Our experiment was performed with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), unique for its ability to collide spin-polarized proton beams.The Endcap Electromagnetic Calorimeter (EEMC) of the STAR detector with its pseudorapidity $\left( \eta \right) $ range between 1.09 and 2.00 and full azimuthal coverage measures energies of photons from $\pi^0$ decays. We consider the invariant mass of all photon pairs in the EEMC as we identify $\pi^0$ candidates. We will present the current status of the analysis of the $\pi^0$ $A_{LL}$ as measured by the EEMC at STAR in 2012 data with center-of-mass energy of 510 GeV.   

Designing a Modern Low Cost Muon Detector to Teach Nuclear Physics

In an effort to make it possible for small institutions to train students in nuclear physics, an attempt is made to design a low cost cosmic ray muon detector (perhaps under 600 dollars) capable of measuring flux vs. solid angle and muon lifetime. In order to expose students to current particle detection technologies, silicon photomultipliers will be coupled with plastic scintillator to provide the signals, and an Arduino, Raspberry Pi, or National Instruments device will interface with the detector. Once designed and built, prototypes of the detector will be used in outreach to K-12 students in the Allentown, PA area.   

Upgrades for the STAR Experiment Slow Controls at Brookhaven National Laboratory

The STAR (Solenoidal Tracker at RHIC) experiment at Brookhaven National Laboratory studies the collisions of relativistic heavy ions. Some components of the control system for STAR have not changed since STAR became operational in 2000. The goal of this project is to upgrade the control system software for easier maintenance. The software upgrade also requires modernizing the hardware in some cases. A prototype for monitoring the Field Cage for the Time Projection Chamber (TPC) and a prototype for controlling the TPC front-end electronics using a programmable logic controller were developed. Newly developed software for the hygrometer to monitor the experiment environment was deployed at the experiment. Details about the software and hardware upgrades, as well as the developed prototypes will be presented.   

Calibrating the PHENIX Muon Piston Calorimeter Using Fits to ADC Distributions

The PHENIX Muon Piston Calorimeter (MPC), a homogeneous electromagnetic calorimeter located in the forward and backward directions (3.1 < $\eta$ < 3.9) is being used to measure transverse energy from RHIC Au+Au collisions obtained in 2010. While the detector has been partially calibrated using the reconstruction of neutral pions in an iterative procedure, the calibration constants for some areas of the detector are not converging. In order to improve the initial set of calibration constants, a parameterization of the energy distributions as a function of distance from the beamline (obtained using well calibrated towers) is used to provide initial values to problem towers in the iterative procedure. The work done to produce this parameterization and its effects on the calibration process will be described.   

Charge-Asymmetry Dependence of Proton Elliptic Flow in 200 GeV Au$+$Au Collisions

The chiral magnetic wave (CMW) is predicted to manifest a finite electric quadrupole moment in the quark-gluon plasma produced in high-energy heavy-ion collisions [1]. This quadrupole moment generates a divergence in the azimuthal anisotropy ($v$2) of positively and negatively charged particles such that $v$2($+)$ \textless $v$2(-). This effect is proportional to the apparent charge asymmetry (Ach) of particles in the same rapidity window. The Ach dependence of $v$2$^{\mathrm{\thinspace }}$has already been observed in the cases of charged pions and kaons [2, 3]. We present preliminary STAR measurements of $v$2$^{\mathrm{\thinspace }}$for protons and anti-protons as a function of Ach$^{\mathrm{\thinspace }}$from $\surd $sNN$^{\thinspace }=$ 200 GeV Au$+$Au collisions for different centrality classes. The results are then compared with the previously reported results of pions and kaons. [1] Y. Burnier, D. Kharzeev, J. Liao and H. Yee, Phys. Rev. Lett. \textbf{107} (2011) 052303. [2] L. Adamczyk, \textit{et al}, Phys. Rev. Lett.?\textbf{114}?(2015) 252302. [3] Q.-Y Shou, Nucl. Phys. A \textbf{931} (2014) 758.   

Comparing Novel Multi-Gap Resistive Plate Chamber Models

Investigating nuclear structure has led to the fundamental theory of Quantum Chromodynamics. An Electron Ion Collider (EIC) is a proposed accelerator that would further these investigations. In order to prepare for the EIC, there is an active detector research and development effort. One specific goal is to achieve better particle identification via improved Time of Flight (TOF) detectors. A promising option is the Multi-Gap Resistive Plate Chamber (mRPC). These detectors are similar to the more traditional RPCs, but their active gas gaps have dividers to form several thinner gas gaps. These very thin and accurately defined gas gaps improve the timing resolution of the chamber, so the goal is to build an mRPC with the thinnest gaps to achieve the best possible timing resolution. Two different construction techniques have been employed to make two mRPCs. The first technique is to physically separate the gas gaps with sheets of glass that are .2mm thick. The second technique is to 3D print the layered gas gaps. A comparison of these mRPCs and their performances will be discussed and the latest data presented.   

Testing Mylar Multi-Gap Resistive Plate Chambers

Quantum Chromodynamics (QCD) is the fundamental theory that successfully explains strong force interactions. To continue the effective study of QCD in nuclear structure, plans are being made to construct an Electron Ion Collider (EIC). Part of the preparation for the EIC includes continued detector development to push beyond their current capabilities. This includes Time of Flight (TOF) detectors, which are used for particle identification. Multi-Gap Resistive Plate Chambers (mRPCs) are a type of TOF detector that typically use glass to make small gas gaps within the detector to produce fast signals when a high energy particle goes through the detector. These extremely thin gaps of 0.2mm are key in achieving the excellent timing resolution capability of these detectors. A new mRPC design is being tested with the goal of reaching a timing resolution of 10ps. This design uses sheets of mylar in place of the glass so that the width of the dividers is smaller, thus vastly increasing the number of gas gaps. Multiple versions of this mylar mRPC have been made and tested. The methods for producing these mRPCs and their performance will be discussed.   

Testing of Front End Electronics for 10ps Time of Flight Detectors

To fully achieve the physics goals of the future Electron Ion Collider (EIC), continued development of the detectors involved is needed. One area of research involves improving the timing resolution of Time of Flight (ToF) detectors from 100ps to 10ps. When the timing resolution of these ToF detectors is improved, better particle identification can be achieved. In addition, as ToF detectors are being constructed with ever improving timing resolution, the need to improve the high speed performance of the fast electronics used in their front-end electronics (FEE) increases. A series of careful measurements has been performed to investigate the performance and efficiency of each element in the FEE chain. The focus of these tests lies on the amplitude transmission efficiency of the high speed signals as a function of frequency, also known as the bandwidth. The components tested include balanced to unbalanced (balun) boards, signal pre-amps, and waveform digitizers. These tests were performed on individual components and with all elements connected over a frequency range of 1MHz to 1GHz. The results of these tests will be presented.   

Reconstruction of K*$^{\mathrm{\pm }}$(892) in Au$+$Au Collisions at $\surd $s$_{\mathrm{NN}} \quad =$ 200 GeV

The Relativistic Heavy Ion Collider (RHIC) produces a hot, dense and deconfined Quantum ChromoDynamics (QCD) medium, called the quark-gluon plasma (QGP), with Au$+$Au collisions at $\surd $s$_{\mathrm{NN}} \quad =$ 200 GeV. The K*$^{\mathrm{\pm }}$(892) resonance is a short-lived particle with a lifetime shorter than the expected lifetime of the QGP. The K* production may provide an effective tool to probe the QGP properties, such as strangeness enhancement. Experimentally, K*$^{\mathrm{\pm }}$ analysis is difficult and less studied previously because of large combinatorial background. In recent years, improvements in data sample statistics and particle identification capability promise better K*$^{\mathrm{\pm }}$ measurements. In this presentation, we report the reconstruction of K*$^{\mathrm{\pm }}$ resonance via the hadronic decay channel K*$^{\mathrm{\pm }}$(892) $\to $K$_{\mathrm{S}}^{\mathrm{0}}\pi^{\mathrm{\pm \thinspace }}$as a function of transverse momentum (p$_{\mathrm{T}})$ up to 5 GeV/c for various collision centrality classes. The data are Au$+$Au collisions at $\surd $s$_{\mathrm{NN}} \quad =$ 200 GeV collected in the year 2011 run from the STAR experiment. Physics implications of our measurements will also be discussed.   

Probing Quark-Gluon-Plasma properties with a Bayesian model-to-data comparison

Experiments at RHIC and LHC study a special state of matter called the Quark Gluon Plasma (QGP), where quarks and gluons roam freely, by colliding relativistic heavy-ions. Given the transitory nature of the QGP, its properties can only be explored by comparing computational models of its formation and evolution to experimental data. The models fall, roughly speaking, under two categories--those solely using relativistic viscous hydrodynamics (pure hydro model) and those that in addition couple to a microscopic Boltzmann transport for the later evolution of the hadronic decay products (hybrid model). Each of these models has multiple parameters that encode the physical properties we want to probe and that need to be calibrated to experimental data, a task which is computationally expensive, but necessary for the knowledge extraction and determination of the models' quality. Our group has developed an analysis technique based on Bayesian Statistics to perform the model calibration and to extract probability distributions for each model parameter. Following the previous work that applies the technique to the hybrid model [1], we now perform a similar analysis on a pure-hydro model and display the posterior distributions for the same set of model parameters. We also develop a set of criteria to assess the quality of the two models with respect to their ability to describe current experimental data. $^{\mathrm{1}}$J.E.Bernhard \textit{et.al.}, arXiv:1605.03954v1   

Stability of the Tower Gains of the STAR Endcap Calorimeter in 2012 Data

The Solenoid Tracker at RHIC (STAR) experiment, based at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC), uses polarized-proton collisions to investigate sea quark and gluon contributions to the proton spin. The STAR detector's Endcap Electromagnetic Calorimeter (EEMC) is of particular interest in this experiment because it covers a kinematic region that is sensitive to gluons carrying a low fraction of the proton momentum, where the gluon's contribution to the spin of the proton is poorly constrained. The EEMC is located in the intermediate pseudorapidity range, 1 \textless $\eta $ \textless 2, and as a lead-scintillator sampling calorimeter, measures the electromagnetic energy of particles produced in the polarized-proton collisions. The calorimeter consists of several layers that include pre-shower, shower maximum, tower, and post-shower detectors. In these detectors, the energy gains, which convert a measured signal into an energy deposition, have been determined using data taken from the year 2012. The sensitivities of the tower energy gains to beam intensity and running time were studied. The results from these sensitivity studies will be reported.   

Quantifying the Chiral Magnetic Effect in Isobaric Heavy Ion Collisions Using Hydrodynamic Simulations

The quark-gluon plasma created in heavy ion collisions is an exotic state of matter in which many unusual phenomena are manifested. One such phenomenon is the "Chiral-Magnetic Effect" (CME), wherein the powerful magnetic fields generated by colliding ions spin-polarize chiral quarks, causing a net transport effect in the direction of the fields. The CME predicts specific charge-dependent correlation observables, for which experimental evidence was reported, although the evidence is subject to background contamination. Isobaric collision experiments have been planned for 2018 at RHIC, which will study this effect by comparing 96Ru-96Ru and 96Zr-96Zr collisions. The two colliding systems are expected to have nearly identical bulk properties (including background contamination), yet about 10\% difference in their magnetic fields due to different nuclear charges. This provides a unique opportunity to disentangle the CME observable and background effects. By simulating this effect using anomalous hydrodynamic simulations, we make a quantitative prediction for the CME-induced signal for several centralities in each of these two colliding systems.​ Our results suggest a significant enough difference in the signal to be experimentally detected- on the order of 15-20\%.   

New Observables for Measuring Rapidity Correlation Structure in Nuclear Collisions

The rapidity dependence of two-particle momentum correlations can be used to probe the viscosity of the liquid produced in heavy nuclei collisions at RHIC. In addition, more refined rapidity structure of these correlations can be used to measure the isotropization time scale $\tau_\pi$ of this liquid [1]. While earlier theory and measurements have focused on correlations of the transverse momentum $p_t$, the interpretation of these measurements is ambiguous because $p_t$ is not a conserved quantity. Correlations of the Cartesian components of transverse momenta, $p_x$ and $p_y$ are easier to understand because they are conserved [1.2]. We use the heavy ion simulation code AMPT to explore the correlations of these quantities. [1] Sean Gavin, George Moschelli, Christopher Zin, (2016), arXiv:1606.02692 [nucl-th]. [2] Scott Pratt, Soeren Schlichting, Sean Gavin, Phys. Rev. C84, 024909 (2011).   

Beam Energy Dependence of Rapidity Correlation Structure in Nuclear Collisions

Viscous diffusion can broaden the rapidity dependence of two-particle transverse momentum fluctuations. Furthermore, detailed changes in the rapidity dependence of these correlations can be used to determine the characteristic time $\tau_\pi$ for the rate of isotropization of the stress energy tensor. Measurements at the top RHIC energy by the STAR collaboration exhibit a rapidity distribution roughly consistent with $\tau_\pi/\nu \sim 10$ [1]. We extend the second order dissipative hydrodynamics with noise of ref. 1 to include a realistic equation of state and temperature dependent transport coefficients. Our computations are used to predict the energy dependence of the rapidity distribution.   

Study of the Beam Energy Dependence of Azimuthal Anisotropy Coefficients and Non-Flow Effects in Small System d$+$Au Collisions at RHIC

Recent measurements of azimuthal anisotropy, v\textunderscore n, in collision systems such as p,d,3He$+$Au suggest that a quark gluon plasma (QGP) may be formed in these small systems, which would be an unexpected discovery. However, this QGP lives for a shorter time than in larger A$+$A systems and it is not clear how the azimuthal anisotropy signals develop. Varying the collision energy in d$+$Au collisions can help to answer this question. However, non-flow effects are more dominant in small systems and must be accounted for in order to draw conclusions. We will show theoretical calculations of v\textunderscore 2 and v\textunderscore 3 in d$+$Au using different models at several collision energies, and we will present a method based on reference fitting to estimate the non-flow component in actual measurements so that they might be better compared to the theory. (Based on work published in J. D. Orjuela Koop, R. Belmont, P. Yin, and J. L. Nagle Phys. Rev. C 93, 044910 -- Published 22 April 2016)   

Results from Hydrodynamic Simulations of p+p Collisions at $\sqrt{s}=7$ TeV

Relativistic viscous hydrodynamics has been successful in describing the quark-gluon plasma formed in heavy ion collisions at RHIC and the LHC. Recently, experiments on proton-proton collisions at the LHC have provided evidence that high-multiplicity p+p collisions may likewise be amenable to a hydrodynamic description. In order to test such a description, we simulate p+p collisions at $\sqrt{s}=7\textnormal{ TeV}$ using the SONIC package, which consists of 2+1-dimensional viscous hydrodynamics followed by a hadron cascade stage. The initial conditions for hydrodynamics are generated using a model which takes into account the fluctuating substructure of the colliding protons. We quantify the effect of proton substructure on measurable quantities such as elliptic flow. Results from the simulations are compared with experimental data from the ATLAS and ALICE experiments at the LHC. In particular, the hydrodynamic approach is shown to reproduce the observed dependence of particle multiplicities on centrality, as well as to provide a reasonable estimate for the elliptic flow $v_2$ at high multiplicities.   

Test Beam Results for The Fast Interaction Trigger Detector of ALICE at the LHC

CERN (European Center for Nuclear Research) is a global laboratory that studies proton and heavy ion collisions at the Large Hadron Collider (LHC). ALICE (A Large Ion Collider Experiment) is one of four large experiments at the LHC. ALICE is dedicated to the study of the transition of matter to Quark-Gluon Plasma in heavy ion collisions. In the present ALICE detector, there are two sub-detectors, (the T0 and V0), that provide minimum bias trigger, multiplicity trigger, beam-gas event rejection, collision time for other sub-detectors, online multiplicity and event plane determination. In order to adapt these functionalities to the collision rates expected for the LHC upgrade after 2020, it is planned to replace these systems with a single system, called the Fast Interaction Trigger (FIT). In this poster we describe the FIT upgrade; show the proposed characteristics of the FIT detectors and present test beam performance results that support the current design parameters. This material is based upon work supported by the National Science Foundation under grants NSF-PHY-1407051 and NSF-PHY-1305280.   

Study of $\eta_c$ decays with the STARLIGHT Monte-Carlo at LHC Run 2 energies

An introduction to ultra-peripheral collisions and the STARLIGHT Monte-Carlo event generator is provided. STARLIGHT is used, in conjunction with PYTHIA 8, to compute the invariant mass spectrum of the $\eta_c$ via its decay channels $\eta_c \rightarrow K^0_S K^+ \pi^- \rightarrow \pi^+ \pi^- K^+ \pi^-$ and $\eta_c \rightarrow K^*(892)^0 K^+ \pi^- \rightarrow K^+ \pi^- K^- \pi^+$. Charge conjugate- and background processes are also studied. Simulations are made for photon-photon production in a pseudorapidity range between $-1$ and $1$ at center-of-mass collision energies of $\sqrt{s}_{NN}=5.12$~TeV in Pb-Pb collisions. The potential for observing these decays in recent LHC heavy-ion data will be discussed.   

A Zero Degree Calorimeter for the High Radiation Environment at LHC

The two ATLAS Zero Degree Calorimeters(ZDC) are hadron calorimeters that measure the energy of non-colliding nuclear fragments thus providing information on the impact parameter in heavy ion collisions and input for the fast online selection of ultra-peripheral collisions. The ZDCs are located downstream of the straight ATLAS beam pipe section, 140 m from the interaction point. The ZDCs are sampling calorimeters and are composed of alternating layers of tungsten plates and quartz radiator. The extreme radiation environment (up to ~20 Grad/yr) causes degradation of the optical performance of the quartz rods, leading to time dependent ZDC performance and frequent repair. A radiation hard ZDC design is being developed at UIUC based on circulating a liquid Cherenkov radiator replacing the present quartz rods. The upgrade aims at using the ZDC in LHC p+Pb runs for the study of nuclear effects in proton structure at low x. The radiation hardness of materials considered for the upgrade will be tested using a passive container that will be installed in place of the ZDC during the ongoing 2016 p+p run at the LHC. The details of the radiation test will be presented together with planned tests on the optical response and isotopic composition of candidate materials after irradiation.   

Comparing Fragmentation Functions in Pb-Pb Collisions using JEWEL

Collisions between lead nuclei at relativistic speeds create a hot, dense state of deconfined quark matter called the quark gluon plasma (QGP). Due to its extreme density, temperature, and abundance of color charge, the QGP gives us a unique opportunity to study strong interactions and test the limits of QCD. Collisions between nuclei produce jets, clusters of particles hadronized from an energetic parton. Jets produced in heavy ion collisions must travel through the energetic and dense QGP, which changes the structure and momenta of the jets, a phenomenon known as jet quenching. By analyzing the changes in hadron fragmentation and momenta, we probe the properties and structure of the QGP. To analyze the jet fragmentation, we simulated lead-lead collisions with JEWEL, a modification to the Monte-Carlo (MC) generator PYTHIA6, and compared the results with ATLAS data at 2.76 TeV and 5 TeV. These comparisons between the ATLAS data and the MC simulation are important for understanding jet quenching in heavy ion collisions. This poster gives an overview of the results of the simulation and how they compare with ATLAS data on fragmentation.   

Examination of Scintillation Light in a Liquefied Mixture of Noble Gas and Other Dopants

Scintillation light behavior in various liquefied gas mixtures is pertinent to the development of noble gas detectors, which have been used for detecting neutrinos and photons, and are fundamental in searching for dark matter. The University of Michigan has been developing a test procedure to examine scintillation light in a mixture of liquid argon and various dopants, as part of development of a liquid argon scintillating time projection chamber to detect neutrons. We are investigating organic dopants due to the efficient transfer of momentum between neutrons and protons from the nuclei of hydrogen atoms. However, some organic molecules known to dissolve in argon tend to absorb the 128 nm argon scintillation light. The status of our experiments and our conclusions on scintillation light in various liquefied gas mixtures will be presented.   

Monte Carlo study of Quark Gluon Plasma using photon jet observables

Relativistic heavy ion collisions create an exotic state of deconfined, nuclear matter called quark gluon plasma (QGP), providing an opportunity to study the strong interaction. In some particularly hard scattered events, a parton with high transverse momentum ($p_\mathrm{T}$) interacts with this medium before fragmenting into a spray of particles, called a jet. Jet properties of heavy ion collisions can be modified relative to expectations from pp collisions; this effect is called jet quenching. Measurement of the jet internal structure can provide information about this effect and about the medium itself. On the other hand, studying systems whose jets are recoiled against photons coming from an initial scattering offers a way to calibrate the momentum of the modified jet. Since photons do not carry color charge, they escape the QGP with their initial momentum intact. On this poster, results using the Monte Carlo event generators Pythia and JEWEL will be presented for fragmentation functions and jet suppression from photon-jet events, alongside experimental data from CMS and ATLAS at a center of mass energy of 2.76 TeV. Predictions are also presented for lead-lead collisions at a center of mass energy of 5.02 TeV.   

Simulation Studies of Backgrounds for the Fermilab SeaQuest Experiment (E906)

The Fermilab SeaQuest experiment uses a 120 GeV proton beam on targets of liquid hydrogen, liquid deuterium, and solid nuclear targets of carbon, iron, and tungsten. The experiment measures the Drell-Yan process of quark-antiquark annihilation to produce muon pairs, with the main physics goal of studying the sea quark distributions in the nucleon and nuclei. Since quark and antiquark annihilation to dimuons is a rare process, there are significant backgrounds due to muons from the decay of pions produced in the target and beam dump. These backgrounds are being studied via simulated proton interactions in a GEANT implementation of the experimental setup. Full simulation of these backgrounds has proved to be difficult because of the extensive computer time needed. Studies to speed up the simulation process will be presented.   

Cosmic Test Stand for Dark Photon Triggers at E906/SeaQuest

The E906/SeaQuest experiment uses the 120 GeV proton beam from Fermilab's Main Injector aimed at a fixed target to produce Drell-Yan events in order to study the quark and antiquark structure of the nucleon. Through interactions with the beam and the 5m long Fe Magnet, which also serves as a beam dump, this experiment has the potential to produce dark photons which would decay into a dimuon pair. To detect these dark photons, we need to install a new detector system that can trigger on these events that will come from areas the present SeaQuest trigger is designed to exclude as background. The detector system will be made of extruded scintillator with waveshifting optical fiber at its center, which will be matched to a 3mm multi-pixel photon counter (MPPC) Silicon Photomultiplier (SiPM). Then we will need to use programs to map the track back to the vertex inside the Fe magnet. This work describes the construction and operation of a test apparatus that was used to study the efficiency along the entire length of these scintillators to be used in the new dark photon trigger.   

Track Reconstruction at SeaQuest

The SeaQuest experiment, at Fermi National Accelerator Laboratory, is a fixed target experiment that uses the Drell-Yan process to measure the quark and antiquark structure in the nucleon sea. A na\"{\i}ve assumption is that the number of anti-up and anti-down quarks within a nucleon sea would be the same. However, evidence shows that this is not true. The goal of SeaQuest is to more accurately measure this asymmetry in the nucleon sea. In this process event tracking is an integral step in analyzing the data collected. This is difficult due to the size of the experiment, the number of detectors and the beam dump. The beam dump is a 5m block of iron that lies just beyond the target to protect the detectors from the beam. This poses a problem for accurately tracking muons back to the target. Therefore, it is important to crosscheck two independent event trackers. Sqerp, the SeaQuest Event Reconstruction Program, is one of these trackers used at SeaQuest. This tracks events through two magnets, 4 detector stations, and 18 planes of wires. Sqerp deals with difficult problems such as matching hits in each detector station and how detector alignment affects this. This poster will focus on the methods used by Sqerp and the work done in optimizing these processes.   

Optimization of Magnet Strength for Event Reconstruction and Analysis at FNAL SeaQuest

The Fermilab E906/SeaQuest experiment primarily means to study the nucleon sea and its antiquark distribution. This experiment collides a 120 GeV proton beam with one of several fixed targets. E906/SeaQuest probes the quark sea with the Drell-Yan process in which a quark from the beam annihilates an antiquark from the target producing a virtual photon that decays into a pair of muons. Two magnets focus the muons through four detector stations in the spectrometer. The first is a solid iron magnet, which also serves as the beam dump and absorber. The second, an open aperture magnet, is the momentum analyzing magnet and is positioned between the first two detector stations. A tracking program reconstructs the trajectories of the particles in the detector to discern their kinematics. In order to correctly analyze data, the magnetic field strength must be accurately known since it affects the momentum of particles passing through the field. This poster focuses on how the magnet's effect on the transverse momentum of the muons affects kinematic reconstruction of both simulated and real events.   

Dark Photon Monte Carlo at SeaQuest

Fermi National Laboratory's E906/SeaQuest is an experiment primarily designed to study the ratio of anti-down to anti-up quarks in the nucleon quark sea as a function of Bjorken x. SeaQuest's measurement is obtained by measuring the muon pairs produced by the Drell-Yan process. The experiment can also search for muon pair vertices past the target and beam dump, which would be a signature of Dark Photon decay. It is therefore necessary to run Monte Carlo simulations to determine how a changed Z vertex affects the detection and distribution of muon pairs using SeaQuest's detectors. SeaQuest has an existing Monte Carlo program that has been used for simulations of the Drell-Yan process as well as J/psi decay and other processes. The Monte Carlo program was modified to use a fixed Z vertex when generating muon pairs. Events were then generated with varying Z vertices and the resulting simulations were then analyzed. This work is focuses on the results of the Monte Carlo simulations and the effects on Dark Photon detection.   

Study of the trigger efficiency for SeaQuest Drell-Yan Dimuons

The SeaQuest (E906) experiment, using the 120 GeV proton beam from the Main Injector at the Fermi National Accelerator Laboratory (FNAL), is studying the quark and antiquark structure of the nucleon using the Drell-Yan process. SeaQuest uses a two magnet focusing spectrometer with four detector stations that include fast plastic scintillator hodoscope planes. The hodoscope arrays along with Field Programmable Gate Arrays(FPGAs) are used to make the SeaQuest trigger system. It is designed to measure events with dimuon pairs from the Drell-Yan process. The signals from each hodoscope, which have adequate timing resolution to determine which 18.9 ns beam pulse the event occurred, are sent to the FPGA trigger modules. In order to get a correct hit pattern, each channel is aligned to the beam RF clock. The trigger is formed when the hits fulfill a dimuon pattern. A program has been developed to analyze and calculate trigger efficiency by using data from hodoscopes. It is important to study trigger efficiency to be used in physics results, such as the cross section of the Drell-Yan process. The method, programming, measurements, and results of this study will be presented.   

Characterization of nonlinear dielectric films for the tuning of microwave cavities for axion searches

The axion is a hypothetical particle that can solve the strong CP problem and that may be the primary component of dark matter in the universe. Experiments such as the Axion Dark Matter eXperiment (ADMX) hope to find the axion through its coupling to photons in the presence of a strong magnetic field. This coupling can be detected using a microwave cavity whose fundamental resonance frequency is matched to that of the photons. By tuning the cavity resonance frequency, the corresponding axion mass range can be scanned. For axion searches above ~1GHz, future generations of ADMX may use an array of small cavities locked to the same frequency. These cavities will be coarsely tuned using a tuning rod as is done in the current generation of ADMX, but fine tuning of individual resonators will be necessary for multi-cavity arrays. A candidate fine tuning method uses nonlinear dielectric films inside the cavities. DC-biasing the films changes their dielectric constant, affecting the frequencies of the cavity modes. This method makes frequency-matched resonator arrays more practical by saving space and minimizing heat load inside the cryostat. This poster presents RF design and simulation and preliminary measurements on the coplanar waveguide resonators used to test the films.   

Investigating $\bar{d} \bar {u}$ asymmetry in the proton sea by combining Statistical and Meson Cloud Models

From perturbative processes, such as gluon splitting, we expect there to be symmetric distributions of $\bar{d}$ and $\bar{u}$ partons in the proton. However, experiment has shown an excess of $\bar{d}$ over $\bar{u}$. This has been qualitatively explained by the Meson Cloud Model (MCM), in which the non-perturbative processes of proton fluctuations into meson-baryon pairs, allowed by the Heisenberg uncertainty principle, create the flavor asymmetry. We have developed a hybrid MCM to describe the $x$-dependence of $\bar{d}$ and $\bar{u}$ in the nucleon sea. We use a convolution of parton distribution functions from a simple statistical model and splitting functions from the Light-Cone Model, (LCM). We show that two-body LCM wave functions are a good representation of MCM splitting functions. The results of our model are compared to experimental data from the Fermilab E866/NuSea experiment. We present predictions for the $\bar{d}/\bar{u}$ ratio that is currently being examined by Fermilab's SeaQuest experiment, E906.   

The effect of pion parton distributions on light-flavor asymmetry in the proton sea

Recent experimental evidence demonstrates an asymmetry in the $\bar{d}$ and $\bar{u}$ content of the proton sea. This asymmetry can be explained by the Heisenberg uncertainty principle, which allows for the fluctuation of a proton into baryon-meson pairs, creating a meson cloud for the proton. We represent the splitting functions for the baryon-meson fluctuations by two-body Light-Cone Model (LCM) wave functions. These splitting functions can then be convoluted with pion valence- and sea-quark parton distribution functions (PDFs) to determine the meson cloud contributions to the $\bar{d}$ and $\bar{u}$ content in the proton. There are many widely accepted PDFs currently used to describe the pion quark distributions. A comparison of convolutions utilizing different pion PDFs is presented. The probability of fluctuation for given baryon-meson pairs has been varied within an acceptable range to determine values yielding closest agreement with E866 data. We also present predictions for the $\bar{d}/\bar{u}$ ratio to be determined by the SeaQuest experiment E906, now running at Fermilab.   

Two-Boson Exchange in Electron-Nucleon Scattering

Researchers are working to determine in-depth information about the proton’s substructure. This includes the charge and current distributions of the proton, described by electromagnetic form factors. These quantities can be determined by computing electron-proton scattering cross sections, which have been calculated to first-order expansion in the fine structure constant, $\alpha$. Experimental discrepancies in the proton's electric-to-magnetic form factor ratio have prompted a need to compute cross sections to second-order expansion in $\alpha$, involving two-boson exchange (TBE) interactions. Two methods exist for computing TBE contributions: one based on hadronic degrees of freedom (suitable at low $Q^2$) and the other on partonic degrees of freedom (applicable at high $Q^2$). Both methods have been claimed to help account for the form factor discrepancy, but ambiguities exist in the separation of the soft and hard parts of the partonic cross sections. This work aims to resolve such ambiguities and pave the way toward a unified description of TBE effects at all $Q^2$ values. Achieving this goal will further pin down the nature of the proton’s interior, and the results in turn can be used to better understand the substructure of the neutron and other hadrons.   

Uniformly Rastering an Electron Beam on a Polarized Cryotarget

The HDice experiment in Hall B of Jefferson Lab will measure excited nucleon states more completely by controlling the spin states of a hydrogen target. For the experiment, an electron beam will be incident on a polarized target of frozen hydrogen-deuteride, and the debris produced will be measured by the CEBAF Large Acceptance Spectrometer. To ensure that sections of the target don't overheat and depolarize, it is necessary to quickly and uniformly move the beam across the circular surface of the target entrance window. This process of distributing a sequence of beam packets over the x-y plane is known as rastering and is accomplished with a pair of electromagnets that deflect the beam along the x and y axes. We mathematically defined a parametric spiral pattern over the surface of the target window. As sine and cosine waves for x(t) and y(t) produce a circular x-y pattern, we scale their amplitudes by √(t) over a repeating interval to fill in the circle. When simulated, this procedure produces a sufficiently uniform distribution of heat throughout the target. Given this pattern, we specify the current as a function of time in the magnets. In our test setup, the circuit's frequency response alters the input pattern, and we are investigating ways to compensate for that effect.   

Determination of the Aluminum Background Signal Fraction in the Qweak Experiment

The Qweak experiment measured a parity violating asymmetry of longitudinally polarized electrons scattered off an unpolarized liquid hydrogen (LH) target, which enabled the determination of the weak charge of the proton. The Qweak experiment measured the most precise electron-proton asymmetry, leading to the most precise determination of the weak charge of the proton. The largest source of background uncertainty comes from the aluminum casing of the LH target; instead of scattering off the LH, a fraction of the polarized electrons scattered off the aluminum casing surrounding the LH, adding to the events of interest in the asymmetry measurement. In order to obtain a more accurate measurement of the weak charge of the proton, the background signal fraction (BSF) due to scattering off the aluminum casing must be removed from the Qweak data. A new approach to this correction is proposed here, which uses the rates from the target when it was filled with a low density hydrogen gas and then scaled up to the rate of the LH target. Though this method introduced a new error, the uncertainty of the density of the hydrogen gas, but it removes sensitivity to errors from previous analysis, and should result in the same BSF as the previous method, but with a smaller error.   

Geometry Calibration of the SVT in the CLAS12 Detector

A new detector called CLAS12 is being built in Hall B as part of the 12 GeV Upgrade at Jefferson Lab to learn how quarks and gluons form nuclei. The Silicon Vertex Tracker (SVT) is one of the subsystems designed to track the trajectory of charged particles as they are emitted from the target at large angles. The sensors of the SVT consist of long, narrow, strips embedded in a silicon substrate. There are 256 strips in a sensor, with a stereo angle of $0-3~^\circ$ degrees. The location of the strips must be known to a precision of a few microns in order to accurately reconstruct particle tracks with the required resolution of 50-60 microns. Our first step toward achieving this resolution was to validate the nominal geometry relative to the design specification. We also resolved differences between the design and the CLAS12, Geant4-based simulation code GEMC. We developed software to apply alignment shifts to the nominal design geometry from a survey of fiducial points on the structure that supports each sensor. The final geometry will be generated by a common package written in JAVA to ensure consistency between the simulation and Reconstruction codes. The code will be tested by studying the impact of known distortions of the nominal geometry in simulation.   

Measuring Quasi-Elastic e-n and e-p Scattering from Deuterium

The main physics goal of Jefferson Lab is to understand how quarks and gluons form nuclei. We are developing algorithms to extract the relative amounts of electron-neutron (e-n) to electron-proton (e-p) scattering events from deuterium in quasi-elastic (QE) kinematics for an approved experiment with the CLAS12 detector. Our analysis focuses on neutrons detected in the CLAS12 calorimeters and protons measured with the CLAS12 toroidal magnetic field. Events were generated with the Quasi-Elastic Event Generator (QUEEG) and passed through the Monte Carlo code {\it gemc} to simulate the CLAS12 response. These simulated events were then reconstructed using CLAS12 Common Tools. We first match the solid angle for e-n and e-p events. The electron information is used to predict the trajectory of both a neutron and proton through CLAS12. If both particles would interact in the CLAS12 volume, we know the sample has the same solid angle for e-n and e-p events. We then select QE events by searching for a nucleon near the predicted position. The angle between the predicted 3-momentum of the nucleon and the measured value, ${\theta}_{pq}$, reaches a peak near zero for QE events, but not for other inelastic events. A cut on ${\theta}_{pq}$ separates QE events from inelastic ones.   

Measuring the Neutron Detection Efficiency in CLAS12

One of the central physics goals of Jefferson Lab is to understand how quarks and gluons form nuclei. To that end, one of the approved experiments in Hall B will measure the magnetic form factor of the neutron with the new CLAS12 detector. We will extract the ratio of electron-neutron to electron-proton scattering events from deuterium which requires a measurement of the neutron detection efficiency (NDE). To measure NDE we will take calibration data using a proton target to produce tagged neutrons from the p(e,e'$\pi^{+}$)n reaction. We are now simulating this reaction and developing the analysis code to extract the NDE. We use PYTHIA 6.4 to generate p(e,e'$\pi^{+}$)n events and simulate the response of CLAS12 with the Geant4-based Monte Carlo code {\it gemc}. To tag the neutron, we use the measured, scattered electron, and $\pi^{+}$ information to predict the neutron's path. If the path intersects the fiducial volume of the CLAS12 electromagnetic calorimeters, then we search for a hit near that point. The NDE is the ratio of the number of neutrons found in the calorimeters to the number of neutrons predicted to hit the calorimeters. The analysis was done using the CLAS12 Common Tools. We observe a rapid rise in the NDE at low neutron momentum and a plateau above 60\%.   

Calibrating a new polarimetry, pulse NMR, with NMR for the polarized $^{\mathrm{3}}$He target.

One of the goals of the Thomas Jefferson National Accelerator Facility (JLab) is the study of the proton and neutron structures. A polarized $^{\mathrm{3}}$He target provides an effective polarized neutron target to study the neutron spin structure. The target polarization is measured with nuclear magnetic resonance (NMR) and electron paramagnetic resonance. New experiments for the JLab 12 GeV program require upgrades to the target which needs a new type of polarimetry -- pulse NMR (PNMR). PNMR uses a radio frequency field to perturb the $^{\mathrm{3}}$He spins which then undergo free induction decay. The amplitude of this oscillating decay is proportional to the $^{\mathrm{3}}$He polarization. The PNMR needs to be calibrated with regular NMR. This project is to perform these calibrations and to study the systemic effects of PNMR. NMR and PNMR measurements were performed sequentially multiple times. ROOT was used to analyze the data and extract the amplitudes of the measurements which are proportional to the polarizations. These amplitudes were plotted to study the PNMR against the established NMR measurements. PNMR appears to have a linear relationship with NMR. The step remaining is to study the systematic uncertainties of the PNMR. When the study is completed, the new polarimetry will be established.   

Particle Identification Using a Ring Imaging Cherenkov Counter

The installation of a Ring Imaging Cherenkov counter (RICH) on the CLAS12 spectrometer in Hall B of Jefferson Lab will aid in particle identification, specifically with regard to the separation between protons, pions, kaons. The RICH functions by detecting a ring of radiation that is given off by particles moving faster than the speed of light in a medium through the use of multi-anode photomultiplier tubes (MAPMTs). Because the size of the ring is dependent on the velocity of the particles, one can separate the incoming charged particles. With 391 MAPMTs being used in the specific design at Jefferson Lab, sophisticated electronic systems are needed to achieve complete data acquisition and ensure the safe operation of RICH. To monitor these electronic systems, the slow control system uses a compilation of graphical user interfaces (GUIs) that communicates and, if necessary, changes certain process variables such as the high voltage going to the MAPMTs and the temperature of the system. My actual project focuses on the development of an efficient and reliable slow control system for this detector as well as a java based analyzer for offline data analysis.   

Magneto-Optic Kerr Effect in a Magnetized Electron Gun

Magnetized electron sources have the potential to improve ion beam cooling efficiency. At the Gun Test Stand at Jefferson Lab, a solenoid magnet will be installed adjacent to the photogun to magnetize the electron beam. Due to the photocathode operating in a vacuum chamber, measuring and monitoring the magnetic field at the beam source location with conventional probes is impractical. The Magneto-Optical Kerr Effect (MOKE) describes the change on polarized light by reflection from a magnetized surface. The reflection from the surface may alter the polarization direction, ellipticity, or intensity, and depends linearly upon the surface magnetization of the sample. By replacing the photocathode with a magnetized sample and reflecting polarized light from the sample surface, the magnetic field at the beam source is inferred. A controlled MOKE system has been assembled to test the magnetic field. Calibration of the solenoid magnet is performed by comparing the MOKE signal with magnetic field measurements. The apparatus will provide a description of the field at electron beam source. The report summarizes the method and results of controlled tests and calibration of the MOKE sample with the solenoid magnet field measurements.   

Research and Development for an Alternative RF Source Using Magnetrons in CEBAF.

At Jefferson Lab, klystrons are currently used as a radiofrequency (RF) power source for the 1497 MHz Continuous Electron Beam Accelerator Facility (CEBAF) Continuous Wave (CW) system. A drop-in replacement for the klystrons in the form of a system of magnetrons is being developed. The klystron DC-RF efficiency at CEBAF is 35-51{\%} while the estimated magnetron efficiency is 80-90{\%}. Thus, the introduction of magnetrons to CEBAF will have enormous benefits in terms of electrical power saving. The primary focus of this project was to characterize a magnetron's frequency pushing and pulling curves at 2.45 GHz with stub tuner and anode current adjustments so that a Low Level RF controller for a new 1.497 GHz magnetron can be built. A Virtual Instrument was created in LabVIEW, and data was taken. The resulting data allowed for the creation of many constant lines of frequency and output power. Additionally, the results provided a characterization of magnetron oven temperature drift over the operation time and the relationship between anode current and frequency. Using these results, the control model of different variables and their feedback or feedforward that affect the frequency pushing and pulling of the magnetron is better developed.   

The Charged Pion Polarizability Experiment at the Thomas Jefferson National Accelerator Facility: Developing Muon Chambers and Experiment Simulation

\tab The Thomas Jefferson National Accelerator Facility has proposed to make a precision measurement of the charged pion polarizability through measurements of $\gamma \gamma \rightarrow \pi^+ \pi^-$ cross sections using the new GlueX detector. This experiment will have a large muon background which must be filtered out of the pion signal. For this issue we are developing an array of Multi-Wire Proportional Chambers (MWPCs) that will allow the pions to be identified from the muons, permitting a precise measurement of the polarizability. Small (1:8 scale) and medium (1:5 scale) sized prototypes have been constructed and tested, and a full scale prototype is currently being assembled. \\ \tab MWPC electronics were developed and tested to amplify the signal from the detection chamber, and were designed to interface with Jefferson Lab’s existing data acquisition system. In order to construct the detectors, a class 10,000 clean room was assembled specifically for this purpose. Lastly, Geant4 software is being used to run Monte Carlo simulations of the experiment. This allows us to determine the optimal orientation and number of MWPCs needed for proper filtering which will indicate how many more MWPCs must be built before the experiment can be run.   

Modeling Compton Scattering in the Linear Regime

Compton scattering is the collision of photons and electrons. This collision causes the photons to be scattered with increased energy and therefore can produce high-energy photons. These high-energy photons can be used in many other fields including phase contrast medical imaging and x-ray structure determination. Compton scattering is currently well understood for low-energy collisions; however, in order to accurately compute spectra of backscattered photons at higher energies relativistic considerations must be included in the calculations. The focus of this work is to adapt a current program for calculating Compton backscattered radiation spectra to improve its efficiency. This was done by first translating the program from Matlab to python. The next step was to implement a more efficient adaptive integration to replace the trapezoidal method. A new program was produced that operates at less than a half of the speed of the original. This is important because it allows for quicker analysis, and sets the stage for further optimization. The programs were developed using just one particle, while in reality there are thousands of particles involved in these collisions. This means that a more efficient program is essential to running these simulations. The development of this new and efficient program will lead to accurate modeling of Compton sources as well as their improved performance.   

Implementing a Java Based GUI for RICH Detector Analysis

The CLAS12 detector at Thomas Jefferson National Accelerator Facility (TJNAF) is undergoing an upgrade. One of the improvements is the addition of a Ring Imaging Cherenkov (RICH) detector to improve particle identification in the 3-8 GeV/c momentum range. Approximately 400 multi anode photomultiplier tubes (MAPMTs) are going to be used to detect Cherenkov Radiation in the single photoelectron spectra (SPS). The SPS of each pixel of all MAPMTs have been fitted to a mathematical model of roughly 45 parameters for 4 HVs, 3 OD. Out of those parameters, 9 can be used to evaluate the PMTs performance and placement in the detector. To help analyze data when the RICH is operational, a GUI application was written in Java using Swing and detector packages from TJNAF. To store and retrieve the data, a MySQL database program was written in Java using the JDBC package. Using the database, the GUI pulls the values and produces histograms and graphs for a selected PMT at a specific HV and OD. The GUI will allow researchers to easily view a PMT's performance and efficiency to help with data analysis and ring reconstruction when the RICH is finished.~   

Comparisons of pion simulations for the MOLLER experiment

The MOLLER experiment at Jefferson Lab will measure the parity-violating asymmetry in M\o{}ller scattering, the scattering of electrons from electrons. A precise measurement of this parity-violating asymmetry will allow us to determine the weak charge of the electron with a precision that improves over the E158 experiment at SLAC. The experiment will scatter electrons from a 11\,GeV beam from atomic electrons in a liquid hydrogen target. The detected particles will include inelastically produced pions, which will be a background to our measurements. In this work we investigate the validity and accuracy of two available pion physics models in order to estimate the uncertainty in the size of the pion background in the simulation. Currently there are two methods of pion models implemented. The LUND model is based on the Pythia event generator and has been used with success in simulations for the SoLID experiment. The Wiser model is based on data from previous pion scattering experiments. Comparison of the rates, cross sections, particle momentum, scattering angles, and other parameters show that both models produce consistent results for the parameters that were studied in this work, within the range of energies and scattering angles of interest to the MOLLER experiment.   

The Sidereal Time Variations of the Lorentz Force and Maximum Attainable Speed of Electrons.

The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab produces electrons that orbit through a known magnetic system. The electron beam's momentum can be determined through the radius of the beam's orbit. This project compares the beam orbit's radius while travelling in a transverse magnetic field with theoretical predictions from special relativity, which predict a constant beam orbit radius. Variations in the beam orbit's radius are found by comparing the beam's momentum entering and exiting a magnetic arc. Beam position monitors (BPMs) provide the information needed to calculate the beam momentum. Multiple BPM's are included in the analysis and fitted using the method of least squares to decrease statistical uncertainty. Preliminary results from data collected over a 24 hour period show that the relative momentum change was less than 10$^{\mathrm{-4}}$. Further study will be conducted including larger time spans and stricter cuts applied to the BPM data. The data from this analysis will be used in a larger experiment attempting to verify special relativity. While the project is not traditionally nuclear physics, it involves the same technology (the CEBAF accelerator) and the same methods (ROOT) as a nuclear physics experiment.   

The CLAS12 Forward Tagger Detector at Jefferson Lab

The CLAS12-Forward Tagger is designed to detect electrons produced by the interaction of CEBAF 11 GeV electron beam with the target. This detector is composed by an electromagnetic calorimeter (FT-Cal), based on lead tungstate scintillating crystals, a hodoscope (FT-Hodo), based on plastic scintillator tiles and two layers of Micromegas trackers (FT-Trck). The Forward Tagger is designed to measure electrons scattered between 2.5 and 5 degrees. Before the installation in the Hall-B of Jefferson Lab, the FT has been assembled in laboratory and is currently tested with cosmic rays. The calorimeter response is being measured to perform the energy calibration of the system. Cosmic rays crossing the calorimeter crystals release on average a fixed amount of energy that can be used to determine the absolute calibration of the system. The stability of system response can be monitored by studying the variation of calibration constants as a function of time. The results obtained in a few weeks of operation indicates that the energy response of the calorimeter is consistent with expectations and does not show significant time dependence.   

Photoproduction of $K^{0}\Sigma^{+}$ at CLAS

Hadron spectroscopy is used to acquire more information on the quark-gluon interactions and existence of excited hadrons. The photoproduction reaction $\gamma p\rightarrow K^{0}_{S}\Sigma^{+}$ using data from two different experiments of CLAS at Jefferson Lab has been analyzed. This reaction is underexplored among the isospin-related $K\Sigma$ channels. In the g12 experiment, photons ranging in energy from 1.1 to 5.4 GeV were incident on a liquid hydrogen target and the differential cross section was extracted. From the g9a experiment, where circularly-polarized photons were incident on a longitudinally-polarized butanol target, the helicity asymmetry E has been determined. In both experiments, events which contained the proton and three-pion final state $\pi^{+}\pi^{-}p\pi^{0}$ were selected and an event-based quality factor determination was used for background subtraction. Monte Carlo simulations were then preformed to determine acceptance corrections for the cross section. These observables will have a significant impact on partial wave analysis that aims on extracting nucleon resonances from photoproduction data.   

Identification of $\Lambda \rightarrow p \mu^- \bar{\nu}_{\mu}$ events using particle tracking detectors

Study of semi-leptonic hyperon decays could reveal possible disagreements with Standard Model (SM) predictions in which lepton universality (LFU) is presumed. Modern nuclear physics experiments such as CLAS and Glue-X have the capability to produce and reconstruct hyperons, including the $\Lambda$ baryon, in large numbers, however identification of semi-leptonic decay events such as $\Lambda \rightarrow p \mu^- \bar{\nu}_{\mu}$ is difficult for two reasons. First, the missing momentum carried by the neutrino decreases kinematic constraints. Second, the background of hadronic decay events in which the pion decays via $\pi^- \rightarrow \mu^- \bar{\nu}_{\mu}$ in proximity to the $\Lambda$ decay vertex necessitates the use of vertexing information. We present a set of techniques, developed in a Monte Carlo-based analysis, for separating small semi-leptonic decay signal from much more prevalent hadronic decay backgrounds. These techniques rely on kinematic observables and, more crucially, tracking and vertexing information. In addition we present a study of signal/background separability and its dependance on a detector's vertexing resolution.   

Computational modeling of single particle scattering over large distances

We present a Monte Carlo simulation of the propagation of a single particle through a large three-dimensional volume under the influence of individual scattering events. In such systems, short paths can be quickly and accurately simulated using random walks defined by individual scattering parameters, but the simulation time greatly increases as the size of the space grows. We present a method for reducing the overall simulation time by restricting the simulation to a cube of unit length; each `cell' is characterized by a set of parameters which dictate the distributions of allowable step lengths and polar scattering angles. We model propagation over large distances by constructing a lattice of cells with physical parameters that depend on position, such that the full set would represent a space within the entire volume available to the particle. With these, we propose the use of Markov chains to determine a probable path for the particle, thereby removing the need to simulate every step in the particle's path. For a single particle with constant velocity, we can use the step statistics to determine the travel time of the particle. We investigate the effect of scattering parameters such as average step distance and possible scattering angles on the probabilities of a cell.   

Determination of Transverse Charge Density from Kaon Form Factor Data

At the level of nucleons making up atomic nuclei, among subatomic particles made up of quarks, K-mesons or kaons represent the most simple hadronic system including the heavier strange quark, having a relatively elementary bound state of a quark and an anti-quark as its valence structure. Its electromagnetic structure is then parametrized by a single, dimensionless quantity known as the form factor, the two-dimensional Fourier transform of which yields the quantity of transverse charge density. Transverse charge density, in turn, provides a needed framework for the interpretation of form factors in terms of physical charge and magnetization, both with respect to the propagation of a fast-moving nucleon. To this is added the value of strange quarks in ultimately presenting a universal, process-independent description of nucleons, further augmenting the importance of studying the kaon's internal structure. The pressing character of such research questions directs the present paper, describing the first extraction of transverse charge density from electromagnetic kaon form factor data. The extraction is notably extended to form factor data at recently acquired higher energy levels, whose evaluation could permit more complete phenomenological models for kaon behavior to be proposed.   

Characterization and Recovery of Lead Tungstate (PWO4) Crystals

The potential of Lead Tungstate (PWO) crystals in EM calorimeters like the Neutral Particle Spectrometer at 12 GeV JLab and future particle identification detectors of the Electron Ion Collider has been researched extensively. The small Moliere radius of PWO crystals make them ideal for use in a compact detector and their light yield outperforms that of other heavy crystals. Recent measurements have shown large variations in crystal properties. This is a major concern for the construction of particle identification detectors. Testing of the crystal uniformity and understanding the origin of the variation have thus become necessary. The characterization of PWO includes measurements of the crystal dimensions, optical transmittance, both longitudinal and transverse, the light yield and decay kinetics to identify slow luminescence components, as well as tests of radiation hardness. Optical clarity after radiation damage can in principle be restored by stimulated recovery with light. Optical bleaching with blue light is the default method, but curing at longer wavelength may be possible. The results of crystal characterization and effects of radiation on optical properties, as well as the effectiveness and practicality of the LED curing system will be discussed.   

Optimizing light collection for low index aerogels used in Cherenkov Detectors

The SHMS aerogel Cherenkov detector built at CUA is used in Hall C at JLab to differentiate Kaons from Protons. It features four refractive aerogel indices ranging from n$=$1.03-1.01. The lowest index is expected to produce a very small signal and it is thus important to collect it with the highest possible efficiency. One way is to cover the interior of the detector with the best possible reflector material. A prototype was built to investigate possible optimizations of light collection for low aerogel refractive indices. Different reflective materials were used on its inner walls and the resulting average number of photoelectrons detected by a photomultiplier tube (PMT) compared. The coincidence trigger for these tests was constructed using two scintillator paddles. This configuration ensures that only cosmic rays passing perpendicularly through the setup are recorded by the computer. The PMTs used in this setup were calibrated using a blue LED, where the PMT is most sensitive. I will discuss the effect of the different reflectors on the average number of photoelectrons recorded, as well as other possible optimizations of light collection including wavelength shifters, and the effect of absorption and scattering on the detector's performance.   

Optimization of Experiment Detecting Kaon and Pion Internal Structure

Pions and kaons are the lightest two-quark systems in Nature. Scientists believe that the rules governing the strong interaction are chirally, symmetric. If this were true, the pion would have no mass. The chiral symmetry is broken dynamically by quark-gluon interactions, giving the pion mass. The pion is thus seen as the key to confirm the mechanism that dynamically generates nearly all of the mass of hadrons and central to the effort to understand hadron structure. The most prominent observables are the meson form factors. Experiments are planned at the 12 GeV Jefferson Lab. An experiment aimed at shedding light on the kaon’s internal structure is scheduled to run in 2017. The experimental setup has been optimized for detecting kaons, but it may allow for detecting pions between values of Q2 of 0.4 and 5.5 GeV2. Measurements of the separated pion cross section and exploratory extraction of the pion form factor from electroproduction at low Q2 could be compared to earlier e-pi scattering data, and thus help validating the method. At high Q2, these measurements provide the first L/T separated cross sections and could help guide planned dedicated pion experiments. I will present possible parasitic studies with the upcoming kaon experiment.   

Chiral Phase Transition in Soft-Wall AdS/QCD

We investigate the chiral phase transition, which describes the shift from broken to restored chiral symmetry at high temperatures and densities, within a soft-wall model of AdS/QCD. Extending previous work in this approach to strongly-coupled quantum chromodynamics, we obtain independent sources of explicit and spontaneous symmetry breaking at finite baryon chemical potential. Using black hole thermodynamics, we explore the effects of temperature and chemical potential on the chiral condensate, in the case of zero and finite quark mass. In the chiral limit, the transition is second-order, with a critical temperature of 155 MeV and critical density of 566 MeV, consistent with lattice calculations. For a physical value of the light quark mass, the transition is a rapid crossover, with a pseudo-transition temperature and density of 151 MeV and 559 MeV, respectively. The mass-splitting between the vector and axial-vector mesons indicates clear chiral symmetry breaking, and is expected to vanish as chiral symmetry is restored. Quantitative analysis of the mass spectra as temperature and density increase reveals that the meson bound states melt before the chiral phase transition occurs.   

Scintillating Bolometer Monte Carlo for Rare Particle Event Searches

This study uses the Geant4 physics simulation toolkit to characterize various scintillating bolometer constructions for potential experimental commissioning. Emphasis is placed on detector sensitivity to neutrinoless double-beta decay. Constructions minimally include a scintillating source material for the decay and an absorber material. Tellurium, Selenium, Germanium and other candidate isotopes are studied as source materials. Various background discrimination techniques are analyzed including reflective housings and anti-reflective coatings upon the source material. Different geometric optimizations are considered. Ability to discriminate incident alpha and beta radiation, as well as photon detection efficiency for each construction is presented.   

Analysis of pion production data in electron-hadron scattering at JLAB using the TMD Parton Model Formalism

I have performed a phenomenological analysis of pion production data from Jefferson Laboratory in semi-inclusive deep inelastic scattering of electrons on unpolarized nucleons and deuterium using the transverse momentum dependent (TMD) parton model formalism. We parameterize the data in terms of TMD parton distribution functions that describe the three-dimensional (3-D) partonic structure of the nucleon. One of the main enigmas of data analysis is how to reliably estimate the errors of the parameters that describe some particular physical process. A common method is to use Hessian matrix or vary the delta chi-square of the corresponding fits to the data. In this particular project we use the so-called bootstrap method that is very robust for error estimation. This method has not been extensively used in the description of the TMD distributions that describe the 3-D nucleon structure. The reliable estimate of the errors and thus reliable predictions for future experiments is of great scientific interest. We are using Python and modern methods of data analysis in this project. The results of the project will be useful for understanding the effects of internal motion of quarks and gluons inside of the proton and will be reported in a forthcoming publication.   

3D Animations for Exploring Nucleon Structure

Over the last few years many intuitive pictures have been developed for the interpretation of electron hadron scattering experiments, such as a mechanism for transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering experiments. While Dr. Burkardt's pictures have been helpful for many researchers in the field, they are still difficult to visualize for broader audiences since they rely mostly on 2-dimensional static images. In order to make more accessible for a broader audience what can be learned from Jefferson Lab experiments, we have started to work on developing 3-dimensional animations for these processes. The goal is to enable the viewer to repeatedly look at the same microscopic mechanism for a specific reaction, with the viewpoint of the observer changing. This should help an audience that is not so familiar with these reactions to better understand what can be learned from various experiments at Jefferson Lab aimed at exploring the nucleon structure.   

Exploration of Similarity Renormalization Group Generators in 1-Dimensional Potentials

The Similarity Renormalization Group (SRG) is used in nuclear theory to decouple high- and low-momentum components of potentials to improve convergence and thus reduce the computational requirements of many-body calculations [Phys. Rev. C 75, 061001 (2007)]. The SRG is a series of unitary transformations defined by a differential equation for the Hamiltonian. The user input into the SRG evolution is a matrix called the generator, which determines to what form the Hamiltonian is transformed. As it is currently used, the SRG evolves Hamiltonian into a band diagonal form. However, due to many-body forces induced by the evolution, the SRG introduces errors when used to renormalize many-body potentials. This makes it unfit for calculations with nuclei larger than a certain size. A recent paper suggests that alternate generators may induce smaller many-body forces [Phys. Rev. C 90, 034302 (2014)]. Smaller many-body force induction would allow SRG use to be extended to larger nuclei. I use 1-dimensional systems of two, three, and four bosons to further study the SRG evolution and how alternate generators affect many-body forces induced.   

Flow-background subtraction in the charge-separation measurements in heavy-ion collisions

Recent azimuthal-angle correlation measurements in high-energy heavy-ion collisions have observed charge-separation signals perpendicular to the reaction plane, and the observations have been related to the chiral magnetic effect (CME) [1]. However, the correlation signal is contaminated with the background contributions due to the collective motion (flow) of the collision system, and it remains elusive to effectively remove the background from the correlation. In this poster, we present a method study with a simple Monte Carlo simulation and the AMPT model [2]. We develop a scheme to reveal the true CME signal via the event-shape engineering with the magnitude of the flow vector, Q: the flow-background is removed at Q $=$ 0. Artificial signal/background effects will also be discussed. [1] D. E. Kharzeev, L. D. McLerran and H. J. Warringa, Nucl. Phys. A \textbf{803}, 227 (2008). [2] Z.W. Lin and C.M. Ko, Phys. Rev. C \textbf{65}, 034904 (2002).   

Extracting the Proton Backward Spin Polarizability using Compton Scattering

The proton spin-polarizabilities (SPs) are properties that quantify the response of the proton spin to electromagnetic waves. The SPs can be expressed in a linear combination called the backward spin polarizability ($\gamma \pi )$ which arises in the cross-section of a Compton scattering event in which the incident photon is scattered at 180 degrees. As the cross-section at this angle cannot be experimentally determined, measurements of $\gamma \pi $ are fitted using data with scattering angles close to 180 degrees. However, as the scattering angle is reduced the cross-section rapidly becomes determined by the values of the individual SPs, not $\gamma \pi $. This project investigated the viability of using cross-section data from different energy and angle bins to extract the $\gamma \pi $ in order to optimize future experiments for $\gamma \pi $ extraction. A Dispersion Relation was used to generate theory points based on randomly specified values of $\gamma \pi $ and SPs for data sets of different energy and scattering angle. This was repeated 2000 times and the $\chi $2 of each iteration was measured to determine if fits to a data set were dependent on the individual SPs values or $\gamma \pi $.   

The Majorana Demonstrator (MJD) Neutrinoless Double-Beta Decay Experiment

While neutrino oscillation has shown that neutrinos have non-zero mass, many questions regarding the nature of the neutrino mass remain. Since they possess no charge, it is possible that neutrinos are Majorana particles, meaning that they are indistinguishable from their antiparticle. MJD aims to probe the Majorana nature of neutrinos by searching for neutrinoless double-beta decay (0$\upsilon \beta \beta )$ of germanium-76, using germanium detectors as both the source and detector for the decay. In 0$\upsilon \beta \beta $ decay, the two neutrinos are exchanged between the two decaying nucleons, resulting in a sharp energy peak at the endpoint energy of the decay. The sensitivity of this experiment relies upon the ability to reduce backgrounds to resolve such a peak, both by constructing a custom low-background apparatus and by active rejection of backgrounds by the use of pulse shape analyses. My research on MJD has included both computational and experimental activities. Modeling the electric fields inside the point contact Ge detectors supports the pulse shape rejection of some background events. Mechanical testing of some custom hardware components and will aid in the reliability of detector operations.   

Identification and Removal of Low Energy Noise Events in the Majorana Demonstrator

The MAJORANA DEMONSTRATOR is an array of enriched, high-purity Germanium (HPGe) p-type point contact (PPC) detectors constructed to demonstrate the necessary background rates for the detection of neutrinoless double-beta decay (0$\nu$$\beta$$\beta$) and establish the feasibility of a tonne-scale experiment. The PPC detectors have excellent electronic noise performance, providing the opportunity to perform searches for various types of dark matter and other BSM physics that manifest at low energies. In this study we identify some sources of noise events in low-energy ($<$200 keV) regions and discuss their removal. Such sources of noise include noise related with external pulsers, crosstalk, and events that occur within the surface layer of the PPC detectors. We present a variety of techniques to remove these events based on off-line digital signal processing, and compare spectra produced before and after their removal.   

Comparison of MAJORANA DEMONSTRATOR calibration data with simulation.

The MAJORANA project aims to detect the neutrino-less double-beta decay of $^{\mathrm{76}}$Ge using an ultra-low background array of enriched HPGe detectors. Observation of this process would indicate that lepton number is violated, with implications for nuclear and high-energy theory as well as the matter asymmetry of the universe. In this work, a comparison of simulation and real calibration data is presented. Through this comparison, we can modify and improve the model of the spectrum, giving a more complete understating of~the detector's response to neutrino-less double-beta decay. The detector resolutions were determined, along with their energy dependence due to electronic noise, charge collection statistics, and charge trapping. I will show different methods we used to determine the scaling constant and calibrate the stimulated data, and will also display the comparison of the real spectrum and the stimulated spectrum after scaling.~   

Determination of the axial radius in quasielastic neutrino-carbon scattering through z-expansion and the correlated fermi gas nuclear model

When studying neutrino oscillations an understanding of charged current quasielastic (CCQE) neutrino-nucleon scattering is imperative. This interaction depends on a nuclear model as well as knowledge of form factors. CCQE data from neutrino scattering off of carbon from the MiniBooNE experiment [1] is analyzed. Like [2] we use the z-expansion for the axial form factor, but instead of an RFG nuclear model [3], we use a Correlated Fermi Gas nuclear model (CFG) [4] to extract the axial radius. References: [1] A. A. Aguilar-Arevalo et al. [MiniBooNE Collaboration], PR D 81, 092005 (2010). [2] B. Bhattacharya, R. J. Hill, G. Paz. PR D 84, 073006 (2011). [3] R. A. Smith and E. J. Moniz, Nucl. Phys. B 43, 605 (1972). [4] O. Hen, B. A. Li, W. J. Guo, L. B. Weinstein and E. Piasetzky, PR C 91, 025803 (2015).   

PROSPECT: Optical Calibration System

The Precision Reactor Oscillation and SPECTrum Experiment (PROSPECT), is a short baseline, reactor neutrino experiment which focuses on measurements of the flux and energy spectrum of antineutrinos emitted from the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Using these measurements, PROSPECT will probe for eV-scale sterile neutrinos while making a high precision measurement of the U-235 antineutrino spectrum. PROSPECT contains two phases; the first phase consists of a mobile detector near the reactor core while the second phase adds a larger fixed detector further from the core. The PROSPECT Phase 1 detector consists of a \textasciitilde 2ton optically segmented liquid scintillator with each segment read-out by two photomultiplier tubes (PMTs). The PMTs are calibrated with a photon source generated by a nanosecond pulsed laser. In this project, we developed a plan to determine the effectiveness of a 450nm fiber-pigtailed diode laser as it coupled with several modules including an optical fiber splitter, an optical diffuser, and an attenuator. The project tested for the system ability to deliver light uniformly to each of the cells in the detector. We will present the design and result of this project as well as discuss how it will be implemented in PROSPECT.   

Neutron Transport Simulations for NIST Neutron Lifetime Experiment

Neutrons in stable nuclei can exist forever; a free neutron lasts for about 15 minutes on average before it beta decays to a proton, an electron, and an antineutrino. Precision measurements of the neutron lifetime test the validity of weak interaction theory and provide input into the theory of the evolution of light elements in the early universe. There are two predominant ways of measuring the neutron lifetime: the bottle method and the beam method. The bottle method measures decays of ultracold neutrons that are stored in a bottle.  The beam method measures decay protons in a beam of cold neutrons of known flux. An improved beam experiment is being prepared at the National Institute of Science and Technology (Gaithersburg, MD) with the goal of reducing statistical and systematic uncertainties to the level of 1 s. The purpose of my studies was to develop computer simulations of neutron transport to determine the beam collimation and study the neutron distribution's effect on systematic effects for the experiment, such as the solid angle of the neutron flux monitor. The motivation for the experiment and the results of this work will be presented.   

Effect of Detector Coincidence Criteria on a High Precision Measurement of the Neutron Lifetime

The UCN$\tau $collaboration is working to measure the mean lifetime of a free neutron to 0.1s using very low energy ``ultracold'' neutrons (UCN). Achieving such high precision is important in a variety of low-energy tests for new physics. A density of UCN is produced in the Los Alamos solid-Dsuper-thermalsource and is then polarized and guided to a magneto-gravitational trap. The UCN that have high enough energy to escape the trapping potential are cleaned out, and the remaining neutrons are left to decay for two time intervals, a short and long holding time. The difference in the two holding times, along with the normalized number of neutrons left in the trap at the end of the holding periods, are used to calculate the average lifetime of the neutrons in the trap. The neutrons are detected using a newly-developed \textit{in situ }activedetector that observes light from a B-coated ZnS scintillation screen via a pair of photomultiplier tubes . An important consideration for this detector is optimizing the signal to background via adjustments of coincidence criteria defining the ``fingerprint'' of a neutron in the detector. A study will be presented showing the effects of adjusting coincidence parameters on the extracted mean lifetime of a neutron in the trap.   

Assembly and Commissioning of a Liquid Argon Detector and Development of a Slow Control System for the COHERENT Experiment

COHERENT is a collaboration whose goal is to measure coherent elastic neutrino-nucleus scattering (CEvNS). COHERENT plans to deploy a suite of detectors to measure the expected number-of-neutrons squared dependence of CEvNS at the Spallation Neutron Source at Oak Ridge National Laboratory. One of these detectors is a liquid argon detector which can measure these low energy nuclear recoil interactions. Ensuring optimal functionality requires the development of a slow control system to monitor and control various aspects, such as the temperature and pressure, of these detectors. Electronics manufactured by Beckhoff, Digilent, and Arduino among others are being used to create these slow control systems. This poster will generally discuss the assembly and commissioning of this CENNS-10 liquid argon detector at Indiana University and will feature work on the slow control systems.   

Slow Monitoring Systems for CUORE

The Cryogenic Underground Observatory for Rare Events (CUORE) is a ton-scale neutrinoless double-beta decay experiment under construction at the Laboratori Nazionali del Gran Sasso (LNGS). The experiment is comprised of 988 TeO\(_2\) bolometric crystals arranged into 19 towers and operated at a temperature of \(\sim\)10 mK. We have developed slow monitoring systems to monitor the cryostat during detector installation, commissioning, data taking, and other crucial phases of the experiment. Our systems use responsive LabVIEW virtual instruments and video streams of the cryostat. We built a website using the Angular, Bootstrap, and MongoDB frameworks to display this data in real-time. The website can also display archival data and send alarms. I will present how we constructed these slow monitoring systems to be robust, accurate, and secure, while maintaining reliable access for the entire collaboration from any platform in order to ensure efficient communications and fast diagnoses of all CUORE systems.   

Simulations toward Effective Calibrations of the CUORE Detector

It is currently unknown whether or not the neutrino is a Majorana or Dirac particle, that is, whether or not the neutrino is its own antiparticle. Observing neutrinoless double-beta decay, a process only possible if neutrinos are Majorana particles, can answer this question. If observed, this process would indicate that Lepton number is not conserved. CUORE's (Cryogenic Underground Observatory for Rare Events) is a bolometer based detector with Te0$_{\mathrm{2}}$ crystal bolometers that is used to search for neutrinoless double-beta decay in $^{\mathrm{130}}$Te. To insure that this detector will identify the energy peaks resulting from neutrinoless double-beta decay precisely, the detectors must be calibrated with gamma sources. To calibrate the detector, twelve strings carrying the calibration source $^{\mathrm{232}}$Th were cooled from 300K to 10mK and installed within and around the bolometer towers. Six strings are distributed around the outside of the towers, and six strings are among the towers. This organization of strings was chosen because the gamma ray radiation from the source strings cannot penetrate more than one or two crystals at low energy. I will present the results from Monte Carlo simulations run in order to understand how to calibrate the COURE detector during operations and how to calibrate the CUORE detector in circumstances where the twelve calibration strings fail to deploy properly.   

Development of the PROSPECT Source Calibration System

PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, is a short-baseline antineutrino experiment consisting of a movable liquid scintillator detector operated near Oak Ridge National Laboratory’s High Flux Isotope Reactor (HFIR). PROSPECT is designed to make a precise measurement of the antineutrino spectrum emitted from $^{235}$U fissions in a highly-enriched uranium reactor core, and to probe for eV-scale sterile neutrinos by examining neutrino oscillations at a distance of 7-12 m from the reactor. These measurements will address the observed reactor anomalies: the deficit in the reactor flux and the deviation in the spectral shape. PROSPECT consists of a ~2-ton segmented liquid scintillator detector. Each segment is read out with two photomultipliers. Energy response and position reconstruction are calibrated using radioactive gamma and neutron sources. We have developed a retractable source deployment system that allows the placement of sources along the length of the detector segments and tested it using PROSPECT-50, a 50-liter detector prototype consisting of two segments. We will present the design of the PROSPECT source calibration system and results from PROSPECT-50.   

Characterizing the future site for PROSPECT

The discovery of neutrino oscillations commenced exploration of a rich field of science at the intersection of nuclear, particle and astrophysics. This brought a number of interesting questions related to the neutrinos to the forefront of scientific literature. PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, aims to help answer some of those questions by precisely measuring the antineutrino flux and energy spectrum 7-9 meters from the highly enriched $^{235}$U reactor core at Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR) with the goal to probe much of the best fit sterile neutrino parameter space. To better probe the sterile neutrino best fit region it is important to minimize the systematic uncertainties, requiring a detailed characterization of the background radiation field. Here we present DANG (the Detector Array to measure Neutron and Gamma radiation), an array deployed at HFIR to characterize spatial and time variations of the emitted background radiation. The array scans the entire proposed volume of the future PROSPECT location, providing a 3-d map of the background. Additionally, the array allows the study of the time evolution of HFIR correlated background to better understand how the reactor's prompt and activation radiation changes as function of the reactor cycle. Both a discussion of the construction and operation of the array will be given as well as a look at first results.   

Data Driven Study of Neutron Response Using Quasielastic Neutrino Scattering in the Minerva Experiment

Understanding how particles behave in detectors is a critical part of analyzing data from neutrino experiments, but neutral particles are difficult to characterize. The purpose of this project was to calibrate the neutron response in Quasielastic antineutrino scattering (QE) events in the Minerva detector. We applied quasi-elastic assumptions to estimate the outgoing neutron kinematics in QE scattering, and then added modifications to improve the model's predictions for neutron response in data. We compared these kinematic predictions of neutron energy and angle to Monte Carlo simulations of QE scattering and to the behavior of reconstructed energy “blobs” that characterize neutral particle behavior in simulated and real Minerva data. Filtering events for neutron energy, angle, and distance from the interaction vertex, we derive calibration functions for both the simulation and real data. Future work will include potential changes to the blobbing algorithms and refinement of the calibration technique using rigorous statistical methods.   

Study of Neutrino Nucleus Interaction

Neutrino-nucleus cross sections in the GeV energy range suffer from large uncertainties, yet good knowledge of these cross sections is essential for the success of the current and next generation of neutrino experiments, particularly DUNE. In this talk, we study the impact of different assumptions in the treatment of neutrino-nucleus and neutrino-nucleon interactions. We show how the results from hadronic experiments at JLab and Mainz concerning the form factor of the nucleons will help to better determine these cross sections.   

A First Analysis of Radiation Length in the NOvA Near Detector

The NOvA experiment is a long-baseline neutrino oscillation experiment based at Fermilab focused on answering the prevailing questions in neutrino physics today: the neutrino mass hierarchy, neutrino CP violation, and precision measurements of \textbar $\Delta $m$^{\mathrm{2}}_{\mathrm{32}}$\textbar , and $\theta_{\mathrm{23}}$ through the observations of the appearance of electron neutrinos and the disappearance of muon neutrinos. The measurement of electron neutrino appearance depends on the detector's ability to distinguish electro-magnetic showers resulting from electrons from backgrounds resulting from photons. The scale of key features in these showers depends on the radiation length of the materials which compose the detector and the degree to which this distance is accurately modeled in simulation determines how well the selection process of electron showers is understood. I present a measurement of the photon conversion distance using photons from pi0 decays in data and simulation which is related to the radiation length by a constant factor.   

Measurement of Magnetic Field Uniformity For a Neutron Electric Dipole Moment Detector with New Lead Endcaps

Over the last several decades, physicists have been measuring the neutron electric dipole moment (nEDM) with greater and greater sensitivity. The latest experiment we are developing will have 100 times more sensitivity than the previous leading experiment. A nonzero nEDM could, among other consequences, explain the presence of more matter than antimatter in the universe. To measure the nEDM with high accuracy, it is necessary to have a very uniform magnetic field inside the detector since non-uniformities can create false signals via the geometric phase effect. One way to improve field uniformity is to add superconducting lead endcaps to the detector, which constrain the fields at their surfaces to be parallel to them. Here, we test how the endcaps improve field uniformity by measuring the magnetic field at various points in a 1/3-scale experimental volume, inferring what the field must be at all other points, and calculating gradients in the field. This knowledge could help guide further steps needed to improve field uniformity and characterize limitations to the sensitivity of nEDM measurements for the full-scale experiment.   

Magnetic field homogeneity for neutron EDM experiment

The neutron electric dipole moment (nEDM) is an observable which, if non-zero, would violate time-reversal symmetry, and thereby charge-parity symmetry of nature.~ New sources of CP violation beyond those found in the standard model of particle physics are already tightly constrained by nEDM measurements. Our future nEDM experiment seeks to improve the precision on the nEDM by a factor of 30, using a new ultracold neutron (UCN) source that is being constructed at TRIUMF. Systematic errors in the nEDM experiment are driven by magnetic field inhomogeneity and instability. The goal field inhomogeneity averaged over the experimental measurement cell (order of 1 m) is 1 nT/m, at a total magnetic field of 1 microTesla. This equates to roughly 10\textasciicircum \textbraceleft -3\textbraceright homogeneity.~ A particularly challenging aspect of the design problem is that nearby magnetic materials will also affect the magnetic inhomogeneity, and this must be taken into account in completing the design. This poster will present the design methodology and status of the main coil for the experiment where we use FEA software (COMSOL) to simulate and analyze the magnetic field.   

Measurement of the Temperature Dependence of the Dielectric Constant of PMMA for the nEDM Experiment at Oak Ridge National Laboratory.

The nEDM experiment at Oak Ridge National Laboratory aims to search for the electric dipole moment of the neutron at the 10$^{\mathrm{-28}}$ level. The experiment is currently in the research and development phase. In the experiment, ultra-cold neutrons stored inside a container made from PolyMethylMethAcrylate (PMMA) will be subjected to a strong electric field. In order to calculate the electric field within the box very precisely, the dielectric constant of PMMA must be known very well. The experiment will take place at 0.4K and it is not known if the dielectric constant of PMMA changes as a function of temperature. In order to test this, a ``Poor Man's Cryostat'' was constructed. PMMA was cooled down to 77K temperature, and the dielectric constant of PMMA was measured as a function temperature. Experimental details and results of the tests will be presented.   

Investigating Electrical Breakdown in Liquid Helium

The SNS nEDM experiment at Oak Ridge National Laboratory aims to search for the electric dipole moment of the neutron (nEDM) at the 3x10$^{\mathrm{-28}}$ level. The experiment is currently in the critical component demonstration phase. The design of the experiment calls for an electric field of 75 kV/cm across the experimental cells between electrodes within a bath of liquid helium (LHe). However, the electric breakdown phenomenon in LHe is poorly understood. Experiments investigating the breakdown of LHe were carried out at Los Alamos National Laboratory using a small-scale high voltage (SSHV) test apparatus at temperatures from 1.7K to 4K. Effects of varying temperature, pressure, and electrode surface conditions on LHe breakdown were investigated. Results and their implications to the SNS nEDM experiment will be presented.   

The Scintillator-Layered Imaging Microscope for Environmental Research (SLIMER)

Identifying the microbes that process nutrients in different ecosystems is vital to understanding those ecosystems. SLIMER is a new detector being developed for this purpose. It incorporates a microcolumnar scintillator in a standard fluorescence microscope coupled with an EMCCD camera. A microbial sample exposed to a radioactive isotope of the nutrient of interest would be scanned by SLIMER. With a goal of a high position resolution, detection of a radioactive event would indicate the area of the slide in which a microbe has absorbed the isotope. The microbes in that location can be sequenced, narrowing down which ones metabolized the nutrient. One potential application of SLIMER is in the study of algae biofilms. An excess of nutrients can result in massive algae growth, damaging water supplies and entire ecosystems. Knowing the microbes that are responsible for the process will result in further understanding of microbial communities in algae, currently of great interest for filtering water systems and mitigating atmospheric CO2. We will report the current status of SLIMER and the development of a corresponding GEANT4 simulation. Ultimately, SLIMER could lead to both control of algae where it is damaging, and artificially produced algae filters where they will be beneficial.   

Object Tracking Vision System for Mapping the UCN$\tau$ Apparatus Volume.

The UCN$\tau$ collaboration has an immediate goal to measure the lifetime of the free neutron to within 0.1%, i.e. about 1~s. The UCN$\tau$ apparatus is a magneto-gravitational “bottle” system. This system holds low energy, or ultracold, neutrons in the apparatus with the constraint of gravity, and keeps these low energy neutrons from interacting with the bottle via a strong $\sim$1~T surface magnetic field created by a bowl-shaped array of permanent magnets. The apparatus is wrapped with energized coils to supply a magnetic field throughout the "bottle" volume to prevent depolarization of the neutrons. An object-tracking stereo-vision system will be presented that precisely tracks a Hall probe and allows a mapping of the magnetic field throughout the volume of the UCN$\tau$ bottle. The stereo-vision system utilizes two cameras and open source openCV software to track an object's 3-d position in space in real time. The desired resolution is $\pm$1~mm resolution along each axis. The vision system is being used as part of an even larger system to map the magnetic field of the UCN$\tau$ apparatus and expose any possible systematic effects due to field cancellation or low field points which could allow neutrons to depolarize and possibly escape from the apparatus undetected.   

Position-sensitive ``movie'' \textit{in situ }neutron detector for the UCN$\tau $ experiment

Precision measurements of neutron $\beta $-decay parameters provide tests of fundamental theories in elementary particle physics and cosmology such as the Standard Model and Big Bang nucleosynthesis. In particular, the UCN$\tau $ experiment aims to measure the mean lifetime of ultracold neutrons confined in an asymmetric magneto-gravitational trap using an \textit{in situ} neutron detector. This detector consists of a 20 nm film of $^{\mathrm{10}}$B on top of a ZnS:Ag scintillating screen. The screen is readout using two photomultipliers which view an array of wavelength shifting fibers optically coupled to the scintillator. When the detector is lowered into the loaded trap, light is emitted due to the charged particles recoiling into the ZnS:Ag when neutrons absorb on the $^{\mathrm{10}}$B. Phase space evolution in the stored neutron population can lead to apparent shifts in the measured neutron lifetime with the detector height. In order to quantify this systematic uncertainty, we are implementing a supplemental 64-channel position-sensitive PMT module with high quantum efficiency and fast time response to image the entire detector \textit{in situ} during measurements. We have characterized a prototype using a ZnS screen and an $\alpha $-particle source along with a prototype lens system and will report the results and future plans.   

A Precision Magnetic Mapper for the UCN$\tau$ Effort

The free neutron lifetime $\tau_n$ is a physical constant that is associated with a variety of experimental tests for new physics. For example, it is used in calculations of expected light element abundances in the universe, which can be compared with observational data. The UCN$\tau$ collaboration has the ultimate goal of measuring the free neutron lifetime to within 0.01\%, or to an error of about $\pm$0.1 s. A trap composed of a bowl-shaped Halbach array of permanent magnets inside of a vacuum jacket that is wrapped by field coils is used to contain polarized, ultracold neutrons (UCN), which are allowed to decay inside the trap. The magnetic array, in conjunction with gravity, keeps the UCN from escaping while the field coils prevent the UCN from depolarizing. However, there will be a systematic error if UCN leave the trap for a reason other than decay. For example, if UCN become depolarized by interacting with magnetic field zeroes or if some surface region of the array has a magnetic field insufficient to repel trapped UCN. We have constructed a robotic arm to move a three-axis Hall probe through the entire volume of the trap with $\sim$1~mm precision to check for low-field regions. We will describe the design and control software for this magnetic mapping system.   

The Depolarization Probability of Ultracold Neutrons in Collision with Material Guide Tubes in a Varying Ambient Magnetic Field

Ultracold neutrons (UCN) are defined as having an energy of $\sim$100~neV. Polarized $\beta$-decay experiments using UCN require consideration of material depolarization for maximizing statistics as well as for understanding and controlling systematic effects. The Los Alamos National Lab UCN team performed an experiment in which UCN were polarized using a 6T longitudinal field. The resulting high-field-seeking spin state neutrons were then introduced into a material test guide. UCN which depolarize become trapped between the high-field region and a shutter, while high-field seeking UCN return through the magnet and are upscattered on a plastic foil. After loading the system with UCN and monitoring the incoming flux, the depolarization probability per bounce can be determined by opening the shutter and counting the population of trapped depolarized neutrons. A determination from this dataset of depolarization per bounce as a function of the ambient magnetic field in guide tubes made of unpolished, mechanically polished, and electropolished Cu, diamond-like carbon coated Cu, and stainless steel will be presented.   

Determining the wavelength spectrum of neutrons on the NG6 beam line at NCNR

Historically, in-beam experiments and bottle experiments have been performed to determine the lifetime of a free neutron. However, these two different experimental techniques have provided conflicting results. It is crucial to precisely and accurately elucidate the neutron lifetime for Big Bang Nucleosynthesis calculations and to investigate physics beyond the Standard Model. Therefore, we aimed to understand and minimize systematic errors present in the neutron beam experiment at the NIST Center for Neutron Research (NCNR). In order to reduce the uncertainty related to wavelength dependent corrections present in previous beam experiments, the wavelength spectrum of the NCNR reactor cold neutron beam must be known. We utilized a beam chopper and lithium detector to characterize the wavelength spectrum on the NG6 beam line at the NCNR. The experimental design and techniques employed will be discussed, and our results will be presented. Future plans to utilize our findings to improve the neutron lifetime measurement at NCNR will also be described.   

MCP detector development for use in Nab detector characterization

The ``Nab'' collaboration will perform a precise measurement of the neutron beta decay parameters ``a'' and ``b'', which constitutes a test for physics beyond the standard model.~ The experiment makes use of the fundamental physics cold neutron beamline at the Spallation Neutron Source at the Fundamental Neutron Physics Beam Line.~ This experiment requires very efficient and precise detection of low energy (30 keV) protons with large area Si detectors.~ To this end, a 30 keV proton source has been built at the University of Manitoba to characterize the Si detector with respect to a custom large area (150mm x 150mm) microchannel plate detector, with know detection efficiency. This poster will present the development of the microchannel plate detector, the theory behind its operation, and its implementation at the University of Manitoba.   

In-Beam Gamma Spectroscopy.

In-beam Gamma ray spectroscopic techniques have been studied using Indian National Gamma Array, IUAC which has a relative photo-peak efficiency of 5{\%}. Data of a previous experiment where high angular momentum states of various nuclides were populated in the fusion-evaporation reaction 75As (28Si, 2p2n) at Elab $=$ 120MeV. When gammas from populated nuclides are emanated during de-excitation, they are emitted with a certain angular distribution depending upon their multipolarity. Angular distribution of dipole and quadrupole transitions in $^{\mathrm{96}}$Ru has been obtained from this data. The efficiency corrected angular distribution plot has been compared with the theoretical angular distribution function. The distribution co-efficients A2 and A$_{\mathrm{4}}$ for dipole and quadrupole were extracted from fitting the distribution with the equation: W ($\theta ) \quad =$ 1$+$A$_{\mathrm{2}}$*P$_{\mathrm{2}}$ (cos $\theta )$ $+$A$_{\mathrm{4}}$*P$_{\mathrm{4}}$ (cos $\theta )$. The Directional-correlation of Oriented Nuclei method was used to assign various other transitions as quadrupole or dipole. A DCO matrix between detectors at 148$^{\mathrm{0}}$ versus 90$^{\mathrm{0}}$ was created using CANDLE. Intensities of transitions that have similar multipolarity as the gated transition would be equal in both the projected spectrums. In case of different multipolarity intensities would vary by a factor of 2. R$_{\mathrm{DCO}}$ plots for $^{\mathrm{96}}$Ru transitions have been obtained. To determine the nature of transitions whether magnetic or electric, a plot between polarization asymmetry ($\Delta )$ and DCO-ratio for transitions in $^{\mathrm{96}}$Ru has been obtained.   

GEANT4 Simulations of Gamma-Gamma Angular Correlations with GRIFFIN

The structure of very neutron rich isotopes has been of recent experimental interest for both nuclear astrophysics and fundamental nuclear structure investigations. In beta-minus decay specifically, beta-delayed gamma cascades can help to shed light on the spin and parity of the states involved. One of the world's most powerful decay spectroscopy tool is the Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei (GRIFFIN) spectrometer at TRIUMF-ISAC in Vancouver, Canada. To investigate the feasibility of these experimental studies, GEANT4 simulations of neutron-rich nuclei are critical, as they are able to provide realistic estimates of what the experimental results may look like. The first such nucleus investigated was $^{44}$P, and both the temporal and angular $\gamma \gamma$ correlations were extracted. Furthermore the simulations were used to model various multipole decay possibilities which provide a powerful tool analyzing collected data from such facilities. In the future, the Facility for Rare Isotope Beams (FRIB) at MSU will be an ideal site for such studies on the most exotic nuclei.   

Information Entropy Exchange in the Path Integral Formulation of Transition Amplitudes

The quantum mechanical transition amplitude for a free particle is calculated using the path integral formalism. This amplitude is the kernel of the Schr\"{o}dinger equation. A Wick rotation of the time increment transforms the kernel into a partition function that depends on the space and time intervals of the transition, with the temperature being proportional to the inverse of the time increment. The information entropy exchange between the system and the observer during the transition is calculated from the partition function. The requirement that this be real-valued leads to uncertainty-type relations. Furthermore, the transition exhibits positive information entropy exchange for small time intervals and negative entropy for large ones. The related statistical weight is inversely proportional to the square root of the time interval. Calculations for interacting systems are in progress.   

Crystal Ball Functional Model

The A2 collaboration of the MAinz MIkrotron is dedicated to studying meson production and nucleon structure and behavior via photon scattering. The photons are made via bremsstrahlung process and energy-tagged using the Glasgow Photon tagger. The photon beam then interacts in a variety of targets: cryogenic, polarized or solid state, and scattered particles deposit their energy within the NaI crystals. Scintillators are able to give results on particles energy and time. Events are reconstructed by combining information from the Tagging spectrometer, the Crystal Ball detector, the TAPS forward wall spectrometer, a Cherenkov detector, and multi-wire proportional chambers. To better understand the detector and experimental events, a live display was built to show energies deposited in crystals in real-time. In order to show a range of energies and particles, addressable LEDs that are individually programmable were used. To best replicate the Crystal Ball, 3D printing technology was employed to build a similar highly segmented icosahedron that can hold each LED, creating a 3D representation of what photons see during experiments. The LEDs were controlled via Arduino microcontroller. Finally, we implemented the Experimental Physics and Industrial Control System to grab live event data, and a simple program converts this data in to color and crystal number data that is able to communicate with the Arduino. Using these simple parts, we can better visualize and understand the tools used in nuclear physics.   

Crystal Ball Replica

The A2 collaboration of the Institute for Nuclear Physics of Johannes Gutenberg University performs research on (multiple) meson photoproduction and nucleon structure and dynamics using a high energy polarized photon beam at specific targets. Particles scattered from the target are detected in the Crystal Ball, or CB. The CB is composed of 672 NaI crystals that surround the target and can analyze particle type and energy of ejected particles. Our project was to create a replica of the CB that could display what was happening in real time on a 3 Dimensional scale replica. Our replica was constructed to help explain the physics to the general public, be used as a tool when calibrating each of the 672 NaI crystals, and to better analyze the electron showering of particles coming from the target. This poster will focus on the hardware steps necessary to construct the replica and wire the 672 programmable LEDS in such a way that they can be mapped to correspond to the Crystal Ball elements.   

Testing of Photomultiplier Tubes in a Magnetic Field

The A1 collaboration at MAMI in Mainz, Germany has designed a neutron detector that can be used in experiments to measure the electric form factor of the neutron. They will measure elastic scattering from the neutron, using the polarized electron beam from MAMI at A1's experimental hall. The detector will be composed of two walls of staggered scintillator bars which will be read out by photomultiplier tubes (PMT), connected to both ends of each scintillator via light guides. The experiment requires a magnetic field with strength of 1 Tesla, 2m away from the first scintillator wall. The resulting fringe field is sufficient to disrupt the PMTs, despite the addition of Mu Metal shielding. The effects of the fringe field on these PMTs was tested to optimize the amplification of the PMTs. A Helmholtz Coil was designed to generate a controlled magnetic field with equivalent strength to the field that the PMTs will encounter. The PMTs were read out using a multi-channel analyzer, were tested at various angles relative to the magnetic field in order to determine the optimal orientation to minimize signal disruption. Tests were also performed to determine: the neutron detector response to cosmic radiation; and the best method for measuring a magnetic field's strength in two dimensions.   

Optimizing the Construction of the A1 Collaboration Neutron Detector

We report on the design and construction of a frame designed to optimize both the time efficiency and construction quality of the large scintillator elements These elements will be assembled to form a neutron detector for use by the A1 Collaboration at the Institute for Nuclear Physics in Mainz, Germany. ~The design had to provide adequate support for the 20 kg scintillator bars while gluing light guides and photomultiplier tubes to both sides of the bars using optical cement. ~The optical cement requires approximately 24 hours to dry and 100 bars have to be glued with this apparatus. To address each of these issues, several different prototypes were designed and reviewed. The selected apparatus minimized size to meet space constraints, with reduced material cost and provided the most time-efficient way to build the neutron detector. Once the schematic design was selected, we produced technical drawings in AutoDesk Inventor. Assembled the structure and completed gluing of the first batch of scintillators, in order to verify the performance. This apparatus was successful at producing high quality scintillators which were evaluated using cosmic rays.   

Synthesis and Characterization of Lithium Carboxylates for Use in Liquid Organic Scintillator Fast Neutron Spectrometers

Aqueous solutions of enriched lithium salts emulsified within liquid organic scintillators have been used for fast neutron spectrometry. However, these emulsions can undergo phase instabilities at loading fractions above a few percent of lithium by mass, which gives rise to poor optical performance. We propose an alternative loading method that directly dissolves long-chain lithium carboxylates into liquid organic scintillator which could potentially avoid the deleterious effects of emulsification. We discuss the synthesis of lithium dodecanoate, lithium octanoate, and lithium hexanoate. We further characterize the loading of a these carboxylates within the liquid scintillator cocktail Ultima Gold AB and a comparable scintillator formulation lacking surfactants in terms of solubility and light transmittance properties.   

Developing an in-situ Detector of Neutron-Induced Fission for Actinide Sputtering Characterization

The physical mechanism describing the transfer of large amounts of energy due to fission in a material is not well understood and represents one of the modern challenges facing nuclear scientists, with applications including nuclear energy and national defense. Fission fragments cause damage to the material from sputtering of matter as they pass through or near the material's surface. We have developed a new technique at the Los Alamos Neutron Science Center for characterizing the ejecta by using ultracold neutrons (neutrons with kinetic energy less than 300 neV) to induce fission at finely controlled depths in an actinide. This program will ultimately provide a detailed description of the properties of the sputtered particles as a function of the depth of the fission in the material. A key component of this project is accurately quantifying the number of neutron induced fissions in the sample. This poster depicts the development of an in-situ detector of neutron-induced fission for the AShES (Actinide Sputtering from ultracold neutron Exposure at the Surface) experiment.   

A multipurpose test stand for scintillator decay lifetimes

We built a prototype test stand in order to measure novel scintillator materials' decay lifetimes. Radiography and imaging are valuable diagnostic tools for studying dynamic experiments, thus new scintillator materials are needed to improve the resolution of the current observational systems. A collaborative effort by the neutron imaging and x-ray radiography teams is underway to study the novel scintillator materials developed at LANL and by outside collaborators. Decay lifetimes are an important characteristic of a scintillator material and so by developing this prototype we have provided an avenue to further scintillator development. We confirmed the effectiveness of this prototype by comparing known scintillator decay lifetimes of LYSO and polystyrene samples. In our proof-of-concept prototype we use an 80 Gs/s oscilloscope. With future implementation of a fully developed test stand, we will use a digital data acquisition system to record complete waveforms to conduct a post-processing analysis of the decay times. Results of the prototype test and potential improvements to final test stand design will be presented. LA-UR-16-25229   

Recoil Detection for the SEparator for CApture Reactions (SECAR)

SECAR will be installed at NSCL/FRIB to directly measure (p,$\gamma$) and ($\alpha$,$\gamma$) reactions that are important in extreme stellar environments. Highly selective recoil detection is necessary with SECAR to identify the heavy products of these reactions. We have developed a gas ionization chamber that augments a standard $\Delta E-E$ design with position sensitive capability. We will describe this unique design and its advantages. Initial testing experiments that characterize the position, energy and atomic number resolution of the detector will be presented. The new recoil detector will be characterized in further in-beam studies in the near future and will be installed at NSCL/FRIB by early 2018.   

The Beta Decay of 32Cl

$^{\mathrm{32}}$Cl is a neutron-deficient isotope with a $\beta $-decay half-life of 298 ms and a spin and parity of 1$^{\mathrm{+}}$. It lies close to stability; therefore it can be produced in large quantities at rare isotope beam facilities making its decay relatively straightforward to study. Previous measurements of $^{\mathrm{32}}$Cl $\beta $-delayed $\gamma $ rays have yielded $\beta $-decay schemes including allowed $\beta $ decay transitions. In this study, we present the results of a more sensitive measurement of $^{\mathrm{32}}$Cl beta decay using the CloverShare array of high-purity germanium detectors at the National Superconducting Cyclotron Laboratory. By acquiring the highest-resolution and highest-statistics $^{\mathrm{32}}$Cl $\beta $-delayed $\gamma $ ray data set to date, this experiment has allowed for the observation of several $\gamma $ ray transitions that had only been previously observed in nuclear reaction experiments. A more complete decay scheme has been constructed, including the first observation of forbidden Gamow-Teller transitions in $^{\mathrm{32}}$Cl $\beta $ decay.   

Off-line collinear laser spectroscopy on stable Ca ions

On-line collinear laser spectroscopy (CLS) relies on the use of stable ion beams to perform critical reference measurements for the extraction of nuclear properties such as nuclear moments and charge radii. An experiment has been approved at NSCL to deduce the charge radii for the Ca ($Z$ = 20) isotopes across $N$ = 20. Discontinuities in charge radius trends at nucleon magic numbers are evidence for large shell gaps. However, no discontinuity is evident in the neighboring Ar ($Z$ = 18) and K ($Z$ = 19) isotopes across $N$ = 20. In preparation for this future experiment, stable $^{40,42,44}$Ca$^+$ beams were produced using a Penning Ionization Gauge (PIG) ion source at the BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL/MSU. These stable isotopes will serve as essential calibrations for future CLS measurements on neutron-deficient Ca isotopes. Details of the off-line CLS experiment, subsequent data analysis, and obtained isotope shifts of $^{42,44}$Ca will be presented.   

Online Analysis of Spin Precession for a New Search of the Atomic EDM of Xe-129 at FRM-II

The existence of a permanent electric dipole moment (EDM) would be a clear signature of time-reversal symmetry violation. Such an observation, at planned levels of sensitivity, would be unambiguous evidence for physics beyond the Standard Model. A search for a permanent EDM in $^{129}$Xe is being conducted at FRM-II, which utilizes $^3$He as a co-magnetometer to improve on the current limits of EDM searches. The experiment is conducted in a magnetically shielded room, which has an ultra-low magnetic field with high stability. The gas mixture of $^{129}$Xe and $^3$He are polarized by spin-exchange optical pumping. In the room, the noble gases precess in a cell with a magnetic and electric field applied where the precession is detected using LTc SQUID sensors. Spin lifetimes have been detected to be more than 2700 seconds for both of the gases. Online analysis of spin precession data taken during test runs will be discussed.   

Determination of the Thickness of the Back Dead-Layer of GRETINA Crystals via Comparisons of Measured Photopeak Efficiencies with GEANT4 Simulations

Measurements of the photopeak efficiency of the GRETINA array up to 3.5 MeV made at the National Superconducting Cyclotron Laboratory with 152Eu and 56Co sources were compared with GEANT 4 simulations. We developed a method of determining the average thickness of the back dead layers of the GRETINA crystals by considering the partial photopeak efficiencies of events including gamma-ray interactions in the back slice of the crystals. The impact of dead-layer thicknesses on the accuracy of simulated photopeak efficiencies and the ratio of photopeak counts measured in the two GRETINA crystal types is discussed.   

Measurements of Masses with the Canadian Penning Trap

The primary focus of the Canadian Penning Trap (CPT) located at Argonne National Laboratory is to determine the masses of various isotopes relevant to the $r $process, an astrophysical process thought to be responsible for the creation of half the elements heavier than iron. Currently, the CPT is operating in conjunction with the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) at Argonne National Laboratory's ATLAS facility in an attempt to measure neutron-rich nuclei produced by a 1.0 Curie source of $^{\mathrm{252}}$Cf. The mass measurements of these nuclei are accomplished by measuring the cyclotron frequency of the isotopes captured in the trap. This frequency is measured with a position-sensitive microchannel plate (MCP), which records the relative position of the isotope in the trap for different phase accumulation times. This summer, the CPT group was able to successfully measure to a precision of 10 keV/c$^{\mathrm{2}}$ the masses of $^{\mathrm{142}}$I and $^{\mathrm{156,158,159}}$Nd, which are key nuclei needed to more accurately model the $r $process. This also marks the first time that any of these nuclei had ever been measured.   

Micro Penning Trap for Continuous Magnetic Field Monitoring in High Radiation Environments

As new facilities for rare isotope beams, like FRIB at MSU, are constructed, there is a need for new instrumentation to monitor magnetic fields in beam magnets that can withstand the higher radiation level. Currently NMR probes, the instruments used extensively to monitor magnetic fields, do not have a long lifespans in radiation-high environments. Therefore, a radiation-hard replacement is needed. We propose to use Penning trap mass spectrometry techniques to make high precision magnetic field measurements. Our Penning microtrap will be radiation resistant as all of the vital electronics will be at a safe distance from the radiation. The trap itself is made from materials not subject to radiation damage. Penning trap mass spectrometers can determine the magnetic field by measuring the cyclotron frequency of an ion with a known mass and charge. This principle is used on the Low Energy Beam Ion Trap (LEBIT) minitrap at NSCL which is the foundation for the microtrap. We have partnered with Translume, who specialize in glass micro-fabrication, to develop a microtrap in fused-silica glass. A microtrap is finished and ready for testing at NSCL with all of the electronic and hardware components setup.   

Neutron multiplicity distributions for neutron-rich projectile fragments at the NSCL

Projectile fragmentation is one of the mechanisms used at nuclear science facilities around the world for the production of rare isotope beams. The study of the projectile fragmentation mechanism informs beam simulation codes, but relatively few studies of the fragmentation process have been done, especially at intermediate energies. The MoNA Collaboration used an 86 MeV/u $^{32}$Mg beam on a natural beryllium target at the National Superconducting Cyclotron Laboratory to produce neutron multiplicities distributions in coincidence with charged fragments for isotopes ranging from $^{29}$Na to $^{20}$F. Particle identification for the isotopes from fluorine, neon, and sodium will be presented, as well as preliminary neutron multiplicities distributions.   

Laser-Induced Fluorescence Measurements for Optical Single Atom Detection for Nuclear Astrophysics

We propose a new highly selective detector to measure rare nuclear reactions relevant for nuclear astrophysics. Our primary interest is the $^{\mathrm{22}}$Ne($\alpha , n)^{\mathrm{25}}$Mg reaction, which is a primary source of neutrons for the s-process. Our proposed detector, in conjunction with a recoil separator, captures the recoil products resulting from the reaction in a cryogenically frozen thin film of solid neon. The fluorescence spectra of the captured atoms is shifted from the absorption spectra by hundreds of nanometers. This allows for the optical detection of individual fluorescence photons against a background of intense excitation light. We will describe our initial studies of laser-induced fluorescence of Yb and Mg in solid Ne. Neon is an attractive medium because it is optically transparent and provides efficient, pure, stable, {\&} chemically inert confinement for a wide variety of atomic and molecular species. Yb is used as a test atom because of its similar atomic structure to Mg and much brighter fluorescence signal.   

Shape Coexistence in $^{69}$Co

The rapid change in nuclear properties with the addition or removal of a few nucleons can provide a wealth of information on nuclear structure. One such example of rapid changes is shape coexistence which has been observed in numerous regions of the nuclear chart. Evidence for coexistence between normal and deformed configurations in the vicinity of the Ni isotopes near N = 40 has been identified in various isotopes of Co, Ni, and Cu. Levels attributed to the cross-shell proton excitations have been observed as a function of neutron number in all three isotopic chain and are observed to systematically decrease in energy with increasing neutron number. Recently, two $β$-decaying states in $_{27}^{69}$Co have been identified. However, their relative energy separation is unknown and there are some suggestions that the deformed configuration is the ground state. Observance of a weak $γ$-ray would, at a minimum, fix the energy difference between the two states of $_{27}^{69}$Co. However, the search for the $γ$-ray transition is difficult due to the long half-life of 750-ms, a strong competition from $β$ decay, and possibly high conversion coefficient. Observance would allow for a better understanding of the systematics of deformation in the Ni region as a function of neutron number.   

Simulation of Neutron Wall and Charged Particle Veto Wall for Heavy Ion Collision

Comparison of neutrons and protons emitted in heavy ion collisions is an observable to probe the density dependence of symmetry energy [Cou16]. The dimension of Neutron Wall (NW) at NSCL is about 2x2 m$^{\mathrm{2}}$ which is made of 25 Pyrex tubes filled with liquid Scintillator NE213 that detects recoil protons when neutron interacts with the scintillator. Although it attains excellent discrimination of $\gamma $\textit{-\textmu } and neutron using Pulse Shape Discrimination method, it fails to discriminate charged particles from neutrons. To ensure 100{\%} rejection of charged particles, we plan to build a Charged Particle Veto wall (VW), which will consist of 25 1-cm thick plastic scintillator bars placed directly in front of NW. Simulations using NPTool [Mat16] have been performed to determine the exact design of the VW. To make sure the VW completely covers the NW, overlap of alternate bars is needed. In the poster, I will show the advantage and disadvantage of the positioning plastic bars in a horizontal versus a vertical position as well as position correlation between NW and VW for signal matching. [Cou16] D. D. S. Coupland et al, Physical Review C \textbf{94}, 011601(R) (2016) [Mat16] A. Matta et al, J. Phys. G: Nucl. Part. Phys. 43 (2016) 045113   

Interpolating mass gap equation between the instant form and the front form of relativistic dynamics

We present a mass gap equation linking between the instant form dynamics and the light-front dynamics by interpolating them together with an interpolation variable. We discuss a nucleon dressed in pion loops with the psudovector {\$}$\backslash $pi NN{\$} coupling and techniques in non-linear dynamics to achieve a numerical result. The equivalence of the light-front, equal-time and covariant formulations in meson-baryon interactions has been previously demonstrated. In particular, the self-energy of a nucleon dressed by pion loops has been discussed to show the universality of the leading nonanalytic behavior of the chiral dynamics consistent with QCD. In this poster, we take the previous self-energy calculation as the kernel of the integral equation and discuss the characteristic of the mass gap equation particularly in the limit of the light-front dynamics.   

Development of detector technologies for neutron beta decay measurements

In the past year we have developed two detector technologies for neutron beta decay measurements. The first is designed specifically to detect the recoil proton from neutron decay. In particular, the PERKEO III experiments planned for the Institut Laue Langevin require detectors with active area greater than about 600 cm\textasciicircum 2 area to achieve the targeted statistical sensitivity. We have developed an implementation of transmission foil detectors utilizing free standing foils of roughly 100nm thickness and 700 cm\textasciicircum 2 area, coated with LiF converting crystal. These foils are placed in an accelerating electric field geometry to first accelerate the protons to 30 kV and then convert them to an electron shower which can be detected with conventional semiconductor or scintillator detectors. We've also begun development of technology that is designed to detect charged particles from neutron-capture reaction on 10B. The UCNtau$_{\mathrm{\thinspace }}$experiment at the Los Alamos National Laboratories requires non-magnetic neutron sensors that can be used to measure the density of neutrons in a magnetic trap. We are employing a multilayer surface detector recently developed at Los Alamos for the UCN flux monitoring, adapting it for a compact, 1 cm\textasciicircum 2 detector and ultralow dark rates. The detector consists of 10B on ZnS scintillating sheet that will be adhered to both faces of an acrylic plate with scintillating optical fibers embedded into it. The optical fibers will be coupled to 2, Hamamatsu micro-PMTs for coincident detection of a neutron event.   

Development of a Position Sensitive Liquid Scintillator Bar-type Detector

The ability to detect neutrons is important for both nuclear reactions and beta decay. Liquid scintillators have the useful property of Pulse Shape Discrimination(PSD), which can be used to separate gamma-ray-induced events when the scintillators are used as neutron detectors. Because of their ability to apply PSD, these liquid scintillators will have many applications in neutron detection, such as a recent experiment conducted at the University of Notre Dame. The liquid scintillators use a xylene based liquid made in-house at Oak Ridge National Laboratory. Naphthalene in the liquid scintillator improves the light output properties of the scintillator. An optimized method for the purification of naphthalene will be discussed as well as the first implementation of an array of these detectors.   

Proton Source for Characterizing and Testing Charged Particle Silicon Detectors

Improvements in experimental design and equipment have increased our capability for future neutron beta decay measurements. The upcoming experiments have the potential to test the Standard Model at the same level as the superallowed nuclear beta decay measurements but without the need for nuclear corrections. Part of the improvement comes from new large-area pixelated silicon detector technology. The precision and accuracy that is demanded by the neutron beta decay experiments require detailed characterization of the detectors. Such characterization can be achieved using a low current, variable energy proton beam. The design and simulation of a proton beam from source through accelerator will be presented.   

Nucleosynthesis in Type II Supernova Explosions

Type II are the most common class of the “core collapse" supernova, involving the destruction of a high mass star ($>8M_{\odot}$). Their death is a result of a self-gravitational force becoming unbalanced as fusion ceases in the stellar core, leading to the collapse of the core to form a neutron star. The propagation of the shock ignites fusion into heavier elements as it progress through the star. This process is the origin of most elements present in the universe. In recent years, the complex nature of the explosion (its hydrodynamics, transport of energy, and the created isotopes) have been studied with increasing physical fidelity. Detailed nucleosynthesis from models of these core collapse supernovae is calculated in a post-processing step, using thermodynamic trajectories. My work on the project has been to develop the tools to visualize the results of post-processing calculations in the 2D grid.   

Development of the Off-line Analysis Code for GODDESS.

Determining (n,$\gamma )$ cross sections on unstable nuclei is important for understanding the r-process that is theorized to occur in supernovae and neutron-star mergers. However, (n,$\gamma )$ reactions are difficult to measure directly because of the short lifetime of the involved neutron rich nuclei. A possible surrogate for the (n,$\gamma )$ reaction is the (d,p$\gamma )$ reaction; the measurement of these reactions in inverse kinematics is part of the scope of GODDESS --- Gammasphere ORRUBA (Oak Ridge Rutgers University Barrel Array): Dual Detectors for Experimental Structure Studies. The development of an accurate and efficient off-line analysis code for GODDESS experiments is not only essential, but also provides a unique opportunity to create an analysis code designed specifically for transfer reaction experiments. The off-line analysis code has been developed to produce histograms from the binary data file to determine how to best sort events. Recent developments in the off-line analysis code will be presented as well as details on the energy and position calibrations for the ORRUBA detectors.   

Time of flight in MUSE at PIM1 at Paul Scherrer Institute

The MUSE experiment at PIM1 at Paul Scherrer Institute in Villigen, Switzerland, measures elastic scattering of electrons and muons from a liquid hydrogen target. The intent of the experiment is~to deduce~whether the radius of the proton is the same when determined from the two different~particle types. Precision timing is an important aspect of the experiment, used to determine particle types, reaction types, and beam momentum. Here we present results for a test setup measuring time of flight between prototypes of two detector systems to be used in the experiment, compared to Geant4 simulations. The results demonstrate time of flight resolution better than 100 ps, and beam~momentum determination at the level of a few tenths of a percent.   

Nuclear Delta Force for Two Valence Nucleons in Quadrupole Deformed Nuclei

The nuclear delta force interaction is studied and modelled for the case of two valence nucleons in the spherical shell model, to be extended to the case of the deformed particle rotor model coupled to a pair of valence nucleons, and compared to data. The spherical shell model treats nucleons as individual particles moving independently within the central Woods-Saxon potential. The Hamiltonian for two nucleons in the same valence shell outside of an inert shell core is then modelled taking into account the nuclear delta force to describe their interaction. This model is then compared to the excited state data for nuclei with two nucleons, of the same type, more than being doubly magic. This nuclear delta force is to be extended to the case of two valence nucleons coupled to a quadrupole deformed rotor, by imposing the D$_2$ symmetry associated with this deformation. This deformation can manifest in an axially or a triaxially deformed rotor, and as such, both cases are considered when coupling the two valence nucleons. The future outlook for this goes to adding a nucleon of particle character in order to probe observed degeneracies.   

Development and Testing of Scintillating Detectors for the Muon g-2 Experiment

The precise value of the muon's anomalous magnetic moment that was measured at Brookhaven National Laboratory E821 differed by more than three standard deviations from predictions of the Standard Model. The Muon g-2 Experiment at Fermilab will attain a more precise measurement by a factor of three by observing the muon spin precession frequency in a magnetic field. This improved measurement could lead to evidence of physics beyond the Standard Model. A thin-scintillator entrance (T0) counter prototype is being tested for possible use in the experiment to determine the intensity and temporal profile of the beam as it is injected into the muon storage ring. The counter is also being evaluated to determine whether it can monitor undesired particles that arrive after the main beam pulse. The unique design of the entrance counter uses a silicon photomultiplier to read the light output from a scintillator. The progress of the design of the T0 entrance counter along with the results of light output tests from a beta source and the SLAC high-energy electron beam are the primary foci of this presentation. The status of scintillating fiber harp beam monitor detectors that will also be used in the g-2 Experiment to detect the position and width of the muon beam will also be presented.   

The $\beta$ Decay of $^{35}$Mg and the Structure of $^{35}$Al

Far from the line of beta-stability, the well described shell structure of nuclei falls apart. Near the $\textit{N = 20}$ shell closure lies the “island of inversion”, an area in which the nuclei exhibit ground states deformed with an intruder configuration. The $^{35}$Al nucleus is near this region and whether it belongs to the island is a focus of this study. The experiment to study the $\beta$ decay of $^{35}$Mg was performed at TRIUMF Laboratory. Studying the resulting data provides the information to obtain half-life measurements for $^{35}$Mg and $^{35}$Al, new level information for $^{35}$Al, and provides branching ratios for the feeding of the Si decay chain from Mg. Analyzing the data from the isotope implantation and decay cycles yielded spectra featuring the exponential decay of the nuclei. Fitting this curve will provide the desired half-lives for $^{35}$Mg and $^{35}$Al. The level scheme for $^{35}$Al will be pieced together through a methodical study of the $\gamma-\gamma$ coincidences with in a $\beta-\gamma$ time difference gate. A detailed description of the methods for eliminating erroneous and unnecessary data will be presented along with the results.   

Optimizing the Timing Resolution for the NEXT Array

In nuclear physics studies there are very few detectors capable of measuring neutron energies in the 0.1-10 MeV energy range with a reasonable resolution. The VANDLE array is the premier detector array for these measurements, yet VANDLE is limited by the its thickness (2.9 cm minimum).The Neutron dEtector with Tracking (NEXT) array would be capable of surpassing the limitations caused by the large size of VANDLE bars. A proposed configuration of each neutron detector consists of ten 3-mm thick plastic scintillators with two or more silicon photomultipliers (SiPMs) attached at each end. To achieve the desired energy resolution for neutron energy measurements through time of flight, the timing resolution between these SiPMs needs to be below 200 ps. A SiPM was placed on each end of a plastic scintillator inside a light-tight electrical box along with a $^{137}Cs$ source. An analog circuit was designed in order to measure the timing difference between the two SiPMs. Different configurations of SiPM sizes, scintillator sizes, and wrappings were tested in order to determine the configuration that yields the best timing resolution. Details of the testing procedures and results will be presented.   

Investigation of Energy Threshold and Neutron-Gamma Discrimination for the NEXT Array

In present nuclear studies, limitations on determining $\gamma$-ray and neutron transitional energies are dependent on the quality and versatility of the detector arrangement. Of particular interest is the 0.1-10 MeV range. Many arrangements are bulky due to traditional photomultiplier tubes (PMTs) and typically have poor resolution at and below the 1 MeV range. The Nuclear dEtector with Tracking (NEXT) project is working to resolve these issues using silicon photomultipliers (SiPMs). SiPMs help to fulfill the increasingly apparent need for compact detectors for neutron detection while enabling measurements from 0.1-10 MeV with excellent resolution. Thin scintillator blocks of EJ-200 and EJ-299-33A plastic were used in conjunction with SiPMs to obtain energy spectra to verify energy threshold values. In addition, a separate project of scintillation light wavelength measurements were performed to determine the capability of EJ-299-33A to distinguish neutron from $\gamma$-ray hits. Methods of noise reduction in the spectrometer were implemented and documented. The analysis of energy measurements and wavelength measurements from the two projects will be presented. This research was funded by the Department of Energy and NNSA.   

Improving Charging-Breeding Simulations with Space-Charge Effects

Rare-isotope-beam facilities use Highly Charged Ions (HCI) for accelerators accelerating heavy ions and to improve measurement precision and resolving power of certain experiments. An Electron Beam Ion Trap (EBIT) is able to create HCI through successive electron impact, charge breeding trapped ions into higher charge states. CBSIM was created to calculate successive charge breeding with an EBIT \footnote{R. Becker, O. Kester, and T. Stoehlker, Journal of Physics: Conference Series 58, 443 (2007)}. It was augmented by transferring it into an object-oriented programming language, including additional elements, improving ion-ion collision factors, and exploring the overlap of the electron beam with the ions. The calculation is enhanced with the effects of residual background gas by computing the space charge due to charge breeding. The program assimilates background species, ionizes and charge breeds them alongside the element being studied, and allows them to interact with the desired species through charge exchange, giving fairer overview of realistic charge breeding. Calculations of charge breeding will be shown for realistic experimental conditions. We reexamined the implementation of ionization energies, cross sections, and ion-ion interactions when charge breeding.   

Studying the nuclear pairing force through 26Mg (18O, 16O) 28Mg

A new Silicon Detector called Tiara is being installed in one of the cyclotrons at Texas A{\&}M. Tiara will be used to study nuclear pairing. The specific reaction that will be studied is the 26Mg (18O, 16O) 28Mg reaction. That is a Magnesium-26 beam impingent on an Oxygen-18 target resulting in a recoiling Oxygen-16 and Magnesium-28. The purpose of this is to find information about nuclear pairing. Nucleons have similar properties to electrons in that they obey the Pauli exclusion principle. This nuclear spin pairing give arise to interesting effects for nuclei with more neutrons than protons. To study this we can add two neutrons to the Mg-26 nucleus. A higher 26Mg (18O, 16O) 28Mg cross section will give a stronger nuclear pairing force because they are more easily accepted by the nucleus.   

Theoretical Predictions of Giant Resonances in $^{\mathrm{94}}$Mo

We perform Hartree-Fock based Random Phase Approximation using~thirty-three common Skyrme interactions~found in the literature for 94Mo. We calculate the strength functions and the Centroid Energies of the Isoscalar Giant Resonances for all multipolarities L0, L1, L2, L3. We compare the calculated Centroid Energies with the experimental value; we also study the Centroid Energy and any correlation it may have with the Nuclear Matter properties of each interaction.   

Profiling Cesium Iodide Detectors and Using Pulse Shape Discrimination to Identify Alpha Particles, Neutrons, and Gamma Rays

The purpose of this research was to investigate the properties of detectors that are to be used in future experiments. First, we investigated the properties of a cesium iodide detector. We placed a mask over the detector's face and used an alpha source to measure the detector's resolution on different areas of the detector. In the second part, we investigated the pulse shape discrimination capabilities of a plastic scintillator. We used the scintillator to detect alpha particles, neutrons, and gamma rays and applied various analysis techniques to identify the waveforms of each type.   

Assembling, cleaning, and testing a unique prototype open-ended cylindrical penning trap

A new experimental beamline containing a prototype cylindrical penning trap has recently been constructed at the Cyclotron Laboratory at Texas A{\&}M University. The new beamline will enable precision experiments that enhance our understanding of the limits on non-SM processes in the weak interaction through the measurement of the $\beta $-$\nu $ correlation parameter for T $=$ 2, 0\textasciicircum $+\to $0\textasciicircum $+$ supper allowed $\beta $-delayed proton emitters. The prototype TAMU TRAP consists of an open-ended cylindrical penning trap of diameter of 90 mm with gold-plated electrodes of oxygen free high conductivity copper to prevent oxidation. The trap's electric quadrupole field is provided by a SHIP TRAPS RF electronic circuit to the four segmented electrodes at the center of the trap while the trap's 7 Tesla radial magnetic field is provided by an Agilent 210 ASR magnet. A discussion of the assembly of the prototype TAMU TRAP, construction of the RF electronic circuit, the experimental set up and alignment of the beamline will be presented. The method used to test the prototype penning trap using an ion source, Faraday cups, and Micro Chanel Plate (MCP) detectors will also be discussed.   

Optimizing the Drell-Yan Trigger for the STAR Forward Meson Spectrometer

Theoretical calculations predict that the transverse single-spin asymmetry, $A_{N}$, for Drell-Yan dilepton production in $pp$ collisions is equal in magnitude and opposite in sign to that for semi-inclusive lepton-proton deep inelastic scattering. Verifying this prediction has been identified as a critical test of our current understanding of factorization in high-energy collisions. The STAR Collaboration at RHIC is planning to measure $A_{N}$ for forward-rapidity Drell-Yan $e^{+}e^{-}$ pairs in 500 GeV $pp$ collisions in Spring, 2017. The $e^{+}e^{-}$ pairs will be detected with the STAR Forward Meson Spectrometer (FMS). We studied the efficiency of the FMS trigger system to detect Drell-Yan events. We found that the current logic is less efficient for those events that carry the greatest spin sensitivity. We have developed an alternative logic scheme that will significantly increase the efficiency while being easy to implement. We are also studying the implications of the new scheme for measurements of $A_{N}$ for forward $J/\psi$ production. The new trigger logic will be described.\\   

Analyzing chiral condensate dependence on temperature and density

Determining the thermodynamic properties of the chiral condensate, the order parameter for chiral symmetry restoration, gives insight into whether there are phase transitions in dense astrophysical objects, such as young neutron stars. The chiral condensate is the scalar density of quarks in the ground state, and its presence violates chiral symmetry. Chiral effective field theory is used to study the behavior of the scalar quark condensate with changing temperature and density of neutron matter. Two-body and three-body chiral nuclear forces were employed to find the free energy and its dependence on the pion mass at lower temperatures. With increasing temperature (up to 100 MeV), the chiral condensate is strongly reduced, indicating a fast approach to chiral symmetry restoration. Chiral restoration seems to be hindered, however, at higher densities (around 0.2 fm\textasciicircum -3). The role of the different perturbative contributions and their change with temperature and density was extracted. Although the dominant contribution is the noninteracting term in the perturbation series expansion, nuclear interactions are important particularly at high densities where they delay chiral symmetry restoration.   

A Study of the quality of CsI detectors and pulse-shape discrimination of scintillators for ?[U+0251]-particles, ?[U+0263]-particles, and neutrons

This project studied the capabilities of two different scintillators, Cesium Iodide (CsI) and p-Terphenyl. First, the resolution of a CsI detector was investigated by exposing only very small areas of its surface at a time to an alpha source. Second, the abilities of p-Terphenyl to detect alpha particles, gamma particles, and neutrons were analyzed through pulse shape discrimination. p-Terphenyl is of particular interest because it will be used in the Mitchell Institute Neutrino Experiment at Reactor (MINER) at Texas A{\&}M University for measuring background data. The information learned from conducting these tests will be useful in understanding and expanding the limits of the experiments in which these detectors will ultimately be used.   

Prospects for the ORNL/TAMU Barium Fluoride Array

Understanding the symmetry energy in the nuclear equation of state is essential to understanding properties such as the structure of a neutron star or its gravitational collapse, leading to supernovae. It has been suggested that to better constrain the symmetry energy one can use the bremmstrahlung gamma rays emitted from the hot, dense nuclear matter in the early stages of heavy ion collisions. These gamma rays have the potential to provide a cleaner probe than the more traditional hadronic probes. To measure these bremmstrahlung photons, barium fluoride scintillation crystals were chosen for their ability to detect photons across a large energy range and for their inherent pulse shape discrimination properties. This summer, the detectors of the TAMU/ORNL barium fluoride array were tested in preparation for such an experiment. Signals from each detector were recorded individually for cosmic rays and radioactive source events. The full waveforms were digitized with flash ADCs. A selected set of detectors was assembled and tested with beam from the K500 cyclotron. With this in-beam data, waveform integration parameters may be optimized. Results from the testing of these detectors with flash digitizers will be presented.   

Thallium extraction from hydrochloric acid media into a deep eutectic solvent using bis(2-ethylhexyl) phosphate

The chemical properties of superheavy elements are relatively unknown due to their short half-lives and difficulty of production. In preparation for a future experiment to study the chemical properties of element 113, separation techniques have been used to study the behavior of its homologs, In and Tl. Previous work studied the liquid-liquid extraction of radioactive $^{\mathrm{201}}$Tl ($t_{\mathrm{\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} }} \quad =$ 3.04 d) from various concentrations of HCl into a mixture of menthol and lauric acid that formed a so-called deep eutectic solvent (DES). This work focuses on the effects of adding an extraction agent, bis(2-ethylhexyl) phosphate (HDEHP), to the DES on the efficiency of thallium extraction. The extraction of Tl(I) was generally poor, both with and without HDEHP added. In contrast, $^{\mathrm{111}}$In ($t_{\mathrm{\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} }} \quad =$ 2.80 d) showed significant extraction using HDEHP added to the same DES. This difference in behavior could potentially be exploited in a future experiment on the chemistry of element 113.   

Monte Carlo Acceptance Simulations for the Prototype Active-Target Time-Projection Chamber

In a previous experiment (Fritsch et al., Phys. Rev. C $\textbf{93}$, 014321) the Prototype Active-Target Time-Projection Chamber (PAT-TPC) was used to investigate the $\alpha$-cluster structure of $^{14}$C by way of a 38~MeV secondary $^{10}$Be beam incident on a 90:10 He:CO$_2$ active target gas at the University of Notre Dame. The $^{10}$Be beam was produced by TwinSol and delivered to the PAT-TPC. In addition to measuring elastic and inelastic $^{10}\text{Be}+\alpha$ resonances, evidence of 3-body decays of $^{14}$C were observed in the data. Current work is being done to create a Monte Carlo simulation to calculate the detector acceptance for the 3-body decays at relevant reaction energies in order to produce normalized cross sections. Preliminary results will be presented.   

Effectiveness of Digital Pulse Processing Using a Slow Waveform Digitizer

Using a waveform digitizer, one can replace nearly all of the analog electronics typically involved in processing pulses from a detector by directly digitizing the signal and processing it using digital algorithms. Algorithms for timing filter amplification, constant fraction discrimination, trapezoidal pulse shaping, peak sensing with pileup rejection, and charge integration were developed and implemented. The algorithms and a digitizer with a sampling rate of 62.5 MS/sec were used to calculate the energy and timing resolution of a various scintillation and solid state detectors. These resolutions are compared against both a traditional charge to digital (QDC), and the analog to digital (ADC) data acquisition setup in use at the High Intensity Gamma Source at Duke University. Preliminary results are presented.   

Characterization of the Shielded Neutron Source at Triangle Universities Nuclear Laboratory

In 2015, Triangle Universities Nuclear Laboratory rebuilt its shielded neutron source (SNS) with the goal of improving neutron beam collimation and reducing neutron and gamma-ray backgrounds. Neutrons are produced via the $^{2}$H(d,n)$^{3}$He reaction and then collimated by heavy shielding to form a beam. The SNS has the ability to produce both a rectangular and circular neutron beam through use of two collimators with different beam apertures. Our work characterized both the neutron beam profiles as well as the neutron and gamma-ray backgrounds at various locations around the SNS. This characterization was performed to provide researchers who use the SNS with beam parameters necessary to plan and conduct an experiment. Vertical and horizontal beam profiles were measured at two different distances from the neutron production cell by scanning a small plastic scintillator across the face of the beam at various energies for each collimator. Background neutron and gamma-ray intensities were measured using time-of-flight techniques at 10 MeV and 16 MeV with the rectangular collimator. We present results on the position and size of neutron beam as well as on the structure and magnitude of the backgrounds.   

Neutron-induced Backgrounds in $^{134}$Xe for Large-Scale Neutrinoless Double-Beta Decay Experiments

$^{136}$Xe is used in large neutrinoless double-beta (0νββ) decay experiments, such as KamLAND- Zen and EXO 200. Though highly purified, $^{136}$Xe still contains a significant amount of $^{134}$Xe. Recently, a new nuclear energy level was found in $^{134}$Xe. If $^{134}$Xe decays from this proposed excited state, it will emit a 2485.7 keV gamma ray. Because this energy lies near the region of interest of $^{136}$Xe 0νββ decay experiments (Q value 2457.8 keV), it could make a significant contribution to the background. A purified gaseous sample of $^{134}$Xe will be irradiated with neutrons of an incident energy of 4.0 MeV at Triangle Universities Nuclear Laboratory and monitored with high-purity germanium detectors. The spectra obtained from these detectors will be analyzed for the presence of the 2581 keV gamma ray. We will report on the status of this experiment. Future plans include expanding this measurement to higher initial neutron energies.   

Study of systematic effects in search for CP-violating decays of positronium

CALIOPE, the CP Abberant Leptons in o-Ps Experiment, searches for CP-violating gamma ray angular correlations in the decay of positronium. It uses a cylindrical array of sodium iodide detectors and an electromagnet to spin-polarize the positronium. Systematics related to the magnetic field, uncertainty of decay origin, and detector geometry and inefficiencies are studied using two Monte Carlo simulations of varying complexity. We present the results of systematics studied using these Monte Carlo simulations and their ultimate impact on the experiment's sensitivity.   

Identification of the Neutral Current Interaction of Neutrinos in Liquid Argon Detectors

The neutral current interaction can occur between any flavor of neutrino and argon. In one possible interaction channel, the neutrino excites the argon nucleus, which then decays via a gamma ray of approximately 10 MeV. In order to identify this interaction in liquid argon detectors, these gamma rays must be differentiated from other particles of similar energies. Gamma rays and electrons of 10 MeV were simulated and reconstructed using the "LArSoft" software package models of liquid argon time projection chambers. The reconstructed products were analyzed spatially to study differentiation of gamma rays from electrons and ability to identify the neutral current interaction.   

Measurements of the 169Tm(n,2n)168Tm cross section between 9.0 and 17.5 MeV

Measurements of the $^{169}$Tm(n,2n)$^{168}$Tm cross section have been performed in 0.5 MeV intervals for neutron energies ranging from 9.0 MeV to 17.5 MeV in order to resolve discrepancies in the current literature data. The neutron activation technique was used with $^{90}$Zr and $^{197}$Au as monitor foils. After irradiation, de-excitation gamma rays were recorded off-line with High-Purity Germanium (HPGE) detectors in TUNL's Low-Background Counting Facility. In addition, data for the $^{169}$Tm(n,3n)$^{167}$Tm reaction have also been obtained from 15.5 MeV to 17.5 MeV. The results of these measurements provide the basis for investigating properties of the interial confinement fusion plasma in deuterium-tritium (DT) capsules at the National Ignition Facility located at Lawrence Livermore National Laboratory.   

TUNL Nuclear Structure Data Evaluation on A = 2-20 Nuclides

Nuclear data represents measured or evaluated probabilities of various physical interactions involving the nuclei of atoms. The nuclear data group at Triangle Universities Nuclear Laboratory (TUNL) compiles, evaluates and disseminates nuclear structure data relevant to light nuclei in the mass region of A = 2 - 20. Our activities primarily involve surveying literature articles and producing recommended values for inclusion into various United States Nuclear Data Program databases, such as Experimental Unevaluated Nuclear Data List (XUNDL) and Evaluated Nuclear Structure Data File (ENSDF). We have projects related to analyzing beta-decay lifetimes, compiling structure data from recently published articles, and producing full nuclear structure data evaluations of nuclides based on all existing literature. The nuclear data disseminated is used for theoretical model development of nuclear physics and for applications involving radiation and nuclear power technologies.   

Upgrade of the TITAN EBIT High Voltage Operation

TRIUMF’s Ion Trap for Atomic and Nuclear science (TITAN) is a setup dedicated to highly precise mass measurements of short-lived isotopes down to 10ms. TITAN’s Electron Beam Ion Trap (EBIT) is a charge breeder integrated into the setup to perform in-trap decay spectroscopy of highly charged ions and increase the precision of mass measurements. In its previous configuration TITAN’s EBIT could not fulfil its maximum design specification due to high voltage safety restrictions, limiting its obtainable charge states. A recently completed upgrade of the high voltage operation that will allow the EBIT to fulfil its design specification and achieve higher charge states for heavier species is undergoing preliminary tests with stable beam. Simulations were performed to optimise the injection and extraction efficiency at high voltage and initial tests have involved using a Ge detector to identify x-rays produced by charge breeding stable ions. Future work comprises exploring electron capture rates of Ne-, He- and H-like charge states of $^{64}$Cu and higher masses, which were not previously accessible. The function of the EBIT within the TITAN setup, the work carried out on the upgrade thus far and its scope for future work will be presented.   

A Solution to Inductive Power Coupling in a Time-Cycled Atom Trap for Beta Decay

The TRINAT group at TRIUMF uses lasers and magnetic fields to confine, cool, and polarize a cloud of beta-decaying neutral alkali atoms to test weak force asymmetry. To alternate between trapping and polarizing the atoms, the trapping magnetic field must be switched on and off. This time-changing magnetic field, created by a pair of co-axial coils, produces eddy currents\textemdash and consequentially resistive heating\textemdash in nearby conductors. This heating may cause undesirable effects, including damage to the delicate pellicle mirrors which are to be used in future experiments. Previously, the current waveform in the coils consisted of two periods of a sinusoid during the on time of the trapping field (this reduces leftover field from eddy currents during the polarization time). We have calculated the relative power coupled to the pellicle mirror mount for various waveforms, and determined that using half a period of a lower-frequency sinusoid couples an order of magnitude less power than the original waveform, and approximately 2 times less than a trapezoidal wave. We measured the lifetime of the trap subject to this new waveform and found it is possible to achieve a lifetime comparable to that of a continuous trap, our best result differing by less than 5 percent.   

Alpha-Gamma Angular Correlation in 209Po Using TIGRESS Integrated Plunger

Alpha decay provides a powerful tool to study structure of heavy nuclei with Z\textgreater 83 (above Pb and Bi). When a gamma ray is emitted following the alpha decay, the alpha-gamma angular correlation can be used to assess the height of Coulomb and centrifugal barriers, which determine the rate of the alpha-particle tunnelling. This correlation can also be used as a tool for spin and parity assignments for the nuclear states involved in the decay. For that reason, an apparatus to study this correlation has been set up at TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, through coupling of the CsI wall of the Tigress Integrated Plunger (TIP) device and TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer (TIGRESS). Alpha-gamma sources can be positioned at the centre of the TIP chamber, which is installed within the centre of TIGRESS. In this study, the sensitivity of the setup is investigated from a comparison of measured and predicted alpha-gamma angular distribution from 209Po decay. So far, around 8000 events with extremely high signal-to-noise ratio have been identified by applying alpha-gamma time correlation and CsI pulse shape identification. Initial angular groups between TIP and TIGRESS detector pairs have been assigned and analyzed. Efficiency of each angular group is currently being investigated. Analysis and results will be presented and discussed.   

Characterization and Optimization of HAGRiD

The Hybrid Array of Gamma Ray Detectors (HAGRiD) of LaBr$_{\mathrm{3}}$(Ce) scintillators has been designed to study the structure of nuclei by observing coincident gamma-rays with transfer reactions and beta-decays. HAGRiD couples with particle detector systems such as the Oak Ridge Rutgers University Barrel Array (ORRUBA) of silicon detectors, the Versatile Array of Neutron Detectors at Low Energy (VANDLE), and beta detection scintillators. The LaBr$_{\mathrm{3}}$(Ce) crystals provide better resolution and intrinsic efficiency compared to NaI crystals and has reduced~infrastructure~and~increased flexibility over germanium detectors. HAGRiD scintillators and Photo Multiplier Tubes (PMTs) are readout by XIA Pixie16 waveform digitizers.~ To achieve the best energy and timing resolution, these digitizers need to be optimized for the signals produced by the PMT attached to each HAGRiD crystal. Work to optimize the performance of the digitizer and characterize~the~performance~of HAGRiD will be discussed.   

Determining the Response Function of HPGe Detectors (Clovershare)

Clovershare is a set of HPGe clover detectors with BGO shields. For the experiments described here (performed at the University of Notre Dame) the detector array consisted of six clover detectors located at 45$^{\circ}$,90$^{\circ}$, and 135$^{\circ}$ on either side of a target all read by a digital data acquisition system (DDAS). The experiment's goal was to determine the gamma strength function of $^{90}$Zr, via measurement of gamma-gamma coincidences following proton capture on $^{89}$Y. To determine the response function of the array over a wide range of energies, gamma-ray spectra from $^{152}$Eu as well as known  resonances in the $^{27}$Al(p,$\gamma$)$^{28}$Si reaction were used. Obtained response function will be presented, as well as the preliminary results for the measured $^{89}$Y(p,$\gamma$$\gamma$)$^{90}$Zr reaction.   

Developing an Independent Helium Gas Purification System.

The Institute for Structure and Nuclear Astrophysics depends on 3He for the study of Nuclear reactions. A 3He recovery system is necessary for the Helium Ion Source at the FN tandem accelerator, due to the prohibitive price of 3He. An offline 3He recovery and purification system was built based on the previous online recovery system. The previous online system purified helium gas at a very slow rate and required the Helium Ion Source to operate. The offline system is operated separate of the Helium Ion Source allowing for fast purification cycles. A re-circulation system was added to the offline system to improve the final purity of 3He. Different He gas flow rates were used in the offline purification system. The effects of flow rates were evaluated on their performance in the Helium Ion Source. Gas samples from different flow rates were then analyzed for contaminants in a Gas Chromatograph. Preliminary results and further improvements will be discussed.   

Precise Measurement of Drift Velocities in Active-Target Detectors

Nuclear experiments with radioactive beams are needed to improve our understanding of nuclei structure far from stability. Radioactive beams typically have low beam rates, but active-target detectors can compensate for these low beam rates. In active-target detectors that are also Time-Projection Chambers (TPC), ionized electrons drift through an electric fieldto a detection device to imagethe trajectory of charged-particle ionization tracks within the chamber's gas volume. The measurement of the ionized electrons' drift velocity is crucial for the accurate imaging of these tracks. In order to measure this drift velocity, we will use a UV laser and photo-sensitive foil in a the ND-Cubedetector we are developing, periodically releasingelectrons from the foil at a known timesand a known distance from the electron detector, thereby precisely measuring the drift velocity \textit{in situ}. We have surveyed several materials to find a material that will work well with typical solid-state UV lasers on the market. We plan to determine the best material and thickness of the foil to maximize the number of photoelectrons. The precision that will be afforded by this measurement of the drift velocity will allow us to eliminate a source of systematic uncertainty.   

Testing of a Micro-channel Plate Detector for Improved TwinSol Measurement

The TwinSol radioactive beam facility at the University of Notre Dame is used to study reactions of nuclear astrophysics and structure interest using in-flight produced radioactive beams~ Such measurements are often limited by the energy resolution, the beam purity, and event identification. Time-of-flight (ToF) measurements of both the produced beam and the reaction products can facility experiments that are not currently possible. ~To carry out these ToF measurements, a micro-channel plate detector (MCP) and foil were setup along th~beam line.~Initial tests have been performed in line with a silicon detector, where the MCP creates a start signal for the particle which stops at the silicon detector. Preliminary results will be discussed further in the presentation.   

Comparing the F-Spin Mass Model to Other Nuclear Mass Models

Nuclear masses and binding energies play an important role in nuclear science and the applications of nuclear science such as nuclear astrophysics. The reliable prediction of nuclear masses far from stability are particularly important for a better understanding of the rapid neutron capture process. We are exploring the implementation of a semi-empirical mass model based on the concept of F-spin in nuclei. This model incorporates the evolution of shape in various regions of the chart of nuclides. Here, with the intent of better predicting nuclear binding energies near the bounds of our experimental knowledge, the F-Spin mass model uses a 9 parameter quadratic equation dependent on the third projection of F-Spin and proton number to evaluate the microscopic portion of all nuclear binding energies. We divide the known 2317 isotopes into 14 different zones for fitting purposes, we are able to generate predictions for nuclear masses in the order of 324 keV. The F-Spin model implied shapes are then compared with a number of other mass models to determine the variations in nuclear structure.   

Simulation of Electron Drift in the Active-Target ND Cube

Nucleosynthesis reactions can be highly sensitive to cluster structure in nuclei. In order to experimentally identify cluster structures in nuclei, we will use a combination of resonant scattering and transfer reactions using an active-target detector called the ND Cube. This active-target detector includes a field cage used to image charged-particle tracks from nuclear reactions. Recording these track images will give us information about the structure of the interacting nuclei through the measurement of reaction cross sections. Before any experiment is performed, it is necessary to run a simulation of the electric field produced by the field cage to ensure the field uniformity is sufficient for our needs. We make use of a finite element analysis program to calculate the electric field for arbitrary shapes and the program Garfield to simulate the electron drift and multiplication in the proportional counting region of the detector. After the simulation is performed and we confirm the electric field uniformity, we can move forward to assemble the field cage and prepare the ND Cube detector for commissioning and future experiments that are aimed at searching for nuclear clusters.   

Efficiency of the High Efficiency Total Absorption Spectrometer (HECTOR)

The p-process is a nucleosynthesis process that occurs in explosive environments such as type II and Ia supernovae and is responsible for production of heavy proton rich nuclei. Gamma rays emitted during these explosions induce several photo-disintegration reactions: ($\gamma$,n), ($\gamma$,p), and ($\gamma,\alpha$). To study these interactions, the inverse of these reactions are measured experimentally. The High Efficiency TOtal absorption spectrometeR (HECTOR) at the University of Notre Dame was built for measuring these reactions. Standard gamma sources $^{60}$Co and $^{137}$Cs and known resonances in $^{27}$Al(p,$\gamma$)$^{28}$Si reaction were used to experimentally determine HECTOR’s summing efficiency. Here, the preliminary analysis will be presented and the results will be compared to the Geant4 simulation of the array. This work was supported by the National Science Foundation under the grant number PHYS-1614442.   

Re-evaluating Claims of Discovery in Data from the ATOMKI 5 MV Van De Graaf Accelerator

Using the electron-positron pair spectrometer at the 5 MV Van de Graaff-accelerator at the Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), Krasznahorkay et al. recently announced data not fitting the Standard Model of particle physics. They claim a 6.8 $\sigma$ excess in internal pair creation at high relative angles for the particle pair released in the isoscalar transition, indicative of a particle of mass circa 16.7 MeV. A hypothetical gauge boson, a carrier of a fifth force, has been proposed as an explanation for the excess. We show that a more mundane explanation may lie in the presence of additional nonresonant decay amplitudes, such as $\alpha$ decay of $^8$Be*. The short time scale for this decay, and the additional dynamics of the four-body system make $^8\text{Be*} \rightarrow 2\alpha e^+e^-$ decay a plausible candidate.   

Environmental Monitoring and Characterization of Radiation Sources on UF Campus Using a Large Volume NaI Detector$\backslash $

h $-abstract-$\backslash $pard Environmental radiation surveys are important for applications such as safety and regulations. This is especially true for areas exposed to emissions from nuclear reactors, such as the University of Florida Training Reactor (UFTR). At the University of Florida, surveys are performed using the RSX-1 NaI detector, developed by Radiation Solutions Inc. The detector uses incoming gamma rays and an Advanced Digital Spectrometer module to produce a linear energy spectrum. These spectra can then be analyzed in real time with a personal computer using the built in software, RadAssist. We report on radiation levels around the University of Florida campus using two mobile detection platforms, car-borne and cart-borne. The car-borne surveys provide a larger, broader map of campus radiation levels. On the other hand, cart-borne surveys provide a more detailed radiation map because of its ability to reach places on campus cars cannot go. Throughout the survey data, there are consistent radon decay product energy peaks in addition to other sources such as medical I-131 found in a large crowd of people. Finally, we investigate further applications of this mobile detection platform, such as tracking the Ar-41 plume emitted from the UFTR and detection of potential environmental hazards.$\backslash $-/abstract-$\backslash $\tex   

Predicting neutron star properties based on chiral effective field theory

The energy per nucleon as a function of density, known as the nuclear equation of state, is the crucial input in the structure equations of neutron stars and thus establishes the connection between nuclear physics and compact astrophysical objects. More precisely, the pressure which supports the star against gravitational collapse is mostly determined by the nature of the equation of state of highly neutron-rich matter. In this contribution, we will report on our work in progress to calculate neutron star masses and radii. The equation of state is obtained microscopically from Brueckner-Hartree-Fock calculations based on state-of-the-art nuclear forces which have been developed within the framework of chiral effective field theory. The latter has become popular in recent years as a fundamental and systematic approach firmly connected to low-energy quantum chromodynamics.   

Neutron Scattering Differential Cross Sections for $^{\mathrm{12}}$C

Because of the prevalence of its use in the nuclear energy industry and for our overall understanding of the interactions of neutrons with matter, accurately determining the effects of fast neutrons scattering from $^{\mathrm{12}}$C is important. Previously measured $^{\mathrm{12}}$C inelastic neutron scattering differential cross sections found in the National Nuclear Data Center (NNDC) show significant discrepancies (\textgreater 30{\%}). Seeking to resolve these discrepancies, neutron inelastic and elastic scattering differential cross sections for $^{\mathrm{12}}$C were measured at the University of Kentucky Acceleratory Laboratory for incident neutron energies of 5.58, 5.83, and 6.04 MeV. Quasi mono-energetic neutrons were scattered off an enriched $^{\mathrm{12}}$C target (\textgreater 99.99{\%}) and detected by a C$_{\mathrm{6}}$D$_{\mathrm{6}}$ liquid scintillation detector. Time-of-flight (TOF) techniques were used to determine scattered neutron energies and allowed for elastic/inelastic scattering distinction. Relative detector efficiencies were determined through direct measurements of neutrons produced by the $^{\mathrm{2}}$H(d,n) and $^{\mathrm{3}}$H(p,n) source reactions, and absolute normalization factors were found by comparing $^{\mathrm{1}}$H scattering measurements to accepted NNDC values. This experimental procedure has been successfully used for prior neutron scattering measurements and seems well-suited to our current objective. Significant challenges were encountered, however, with measuring the neutron detector efficiency over the broad incident neutron energy range required for these measurements.   

Accelerating Convergence by Change of Basis for No-Core Configuration Interaction Calculations

\textit{Ab initio} no-core configuration interaction (NCCI) calculations attempt to describe the structure of nuclei using realistic internucleon interactions. However, we can only describe these many-body systems within the limits of our computational power. As the number of nucleons increases, the calculations require more memory and processing power to reach convergence. Being able to accelerate convergence is crucial in extending the reach of NCCI calculations. Convergence can be obtained through a change of basis, for which we need to compute the overlaps of the radial functions for the new basis with those for the old basis. A large number of overlaps must be computed in order to accurately transform the many-body problem. Using alternative bases also requires the calculation of the one-body matrix elements for operators such as $r^{2}$ and $p^{2}$ in the new basis. We report a computer code that uses cubic spline interpolation to compute radial overlaps and radial integrals. This code facilitates using new bases to accelerate the convergence of NCCI calculations.   

Analysis of Historical Coins by X-ray Fluorescence

Using different setups of the EDAX Orbis Micro X-ray Fluorescence (XRF) Analyzer, we have learned more about the limitations and optimizations of the XRF method and collected data about early British and Spanish colonial silver coins. XRF spectrometry was used to study Mexican, Bolivian, and Massachusetts silver coins from the University of Notre Dame's Rare Books and Special Collections Department. Runs were performed in both air and vacuum conditions, and the x-ray beam diameter was compared between 1 and 0.03 mm. Using these methods we were able to contribute to the understanding of the historical coinage as well as learn about the best ways to use the method. During analysis we found significant differences in the spectra for silver L shell excitation and silver K shell excitation when switching from 0.03 to 1mm x-ray beam widths. Our data trends also fit with the historical theory that the coinage from the Massachusetts' mint were created by melting down Spanish silver coins (like the ones made from Mexico and Bolivia) and adding a small percent more of copper. We have the intent to build on what we have learned by also studying some Roman Denarii in the future, and by trying to create a custom designed version of the XRF which can be moved more easily and provide quick scans for a larger number of artifacts.   

Purification of Germanium Crystals by Zone Refining

Germanium zone refining is one of the most important techniques used to produce high purity germanium (HPGe) single crystals for the fabrication of nuclear radiation detectors. During zone refining the impurities are isolated to different parts of the ingot. In practice, the effective isolation of an impurity is dependent on many parameters, including molten zone travel speed, the ratio of ingot length to molten zone width, and number of passes. By studying the theory of these influential factors, perfecting our cleaning and preparation procedures, and analyzing the origin and distribution of our impurities (aluminum, boron, gallium, and phosphorous) identified using photothermal ionization spectroscopy (PTIS), we have optimized these parameters to produce HPGe. We have achieved a net impurity level of $\sim10^{10}$/cm$^{3}$ for our zone-refined ingots, measured with van der Pauw and Hall-effect methods. Zone-refined ingots of this purity can be processed into a detector grade HPGe single crystal, which can be used to fabricate detectors for dark matter and neutrinoless double beta decay detection.   

Photomultiplier Tubes at Cryogenic Temperatures

Liquid noble gas scintillators are widely used in experiments searching for physics beyond the Standard Model. Photomultiplier Tubes (PMTs) working at cryogenic temperatures have been developed as the primary light readout device in those experiments. Three PMTs from Hamamatsu Photonics K.K. (R6041, R11065, and R8520) have been systematically characterized at liquid nitrogen temperature. The high voltage dividing circuits for two of the PMTs were custom-built to make sure there is similar performance at both room and liquid nitrogen temperatures. Their dark count rates at both temperatures were measured. Also measured were their single photoelectron responses at both temperatures using 300, 340, 370, and 420 nm LEDs. The intention is to couple these PMTs directly with inorganic scintillators at liquid nitrogen temperature to achieve high light yeilds for rare-event searches.   

Correlation Between Underground Radon Gas and Dormant Geological Faults

This work studies the concentration of radon in soil around a fault in the East Franklin Mountains in the El Paso area in West Texas. It is found that the in-soil production of radon is correlated to the existence of a fault even if it has not had any recorded activity in recent geological times. This adds to previous observations that link the production of radon to seismic activity, and seems to indicate that in non-active faults the radon production is due mainly to the radioactivity of the top soil and to the transport properties of the medium and not to deeper seismic activity. These results open the possibility of using in-soil radon gas concentrations as an examination tool of dormant faults.   

Chiral vibrations and collective bands in $^{104}$Mo

High spin states of the neutron-rich $^{104}$Mo nucleus which is known to be triaxial have been reinvestigated by analyzing the $\gamma$-rays in the spontaneous fission of $^{252}$Cf with Gammasphere. Both $\gamma$-$\gamma$-$\gamma$ and $\gamma$-$\gamma$-$\gamma$-$\gamma$ coincidence data were analyzed. A new $\Delta$I=1 band has been discovered. The new band is proposed to have a tentative 5$^-$ band head and form a class of chiral doublets with another 4$^-$ band previously found by our group [1]. Angular correlation measurements have been performed to determine spin and parity of the 4$^-$ chiral band head. The energies of the two sets of chiral bands are very similar to the chiral bands observed in $^{106}$Mo [2], e.g. the two 5$^-$ levels in $^{104}$Mo are at 2211.9 and 2276.8 keV with $\Delta$E=65 keV and in $^{106}$Mo, 1952.4 and 2090.6 keV with $\Delta$E=138 keV [2]. Now at every spin 5$^-$, 6$^-$, 7$^-$, 8$^-$, the separation energies of the same spin states are about a factor of two smaller than in $^{106}$Mo. This indicates even better agreement with expectations for two sets of chiral bands. [1] E.F. Jones et al., Physics of Atomic Nuclei, Vol. 69, 1198 (2006). [2] S.J. Zhu et al., Eur. Phys. J. A 25, 459 (2005).   

New determination of the Ba-Mo yield matrix for $^{252}$Cf

Using quadruple-coincidence events of prompt fission gamma rays from 2000 Gammasphere data on spontaneous fission of $^{252}$Cf, we made a careful analysis of the yield matrix of coincident pairs of barium (Z=56) and molybdenum (Z=42) fission fragments. The accuracy of previously determined yield matrices is improved upon with the use of higher accuracy quadruple-coincidences, the increased statistics of the most recent Gammasphere data, and improved level schemes for barium and molybdenum isotopes [1-3]. The previously proposed extra-hot-fission mode (up to ten neutrons evaporated) has been confirmed in our reanalysis. Our results are well in agreement with the results from the 1995 Gammasphere data analysis of Ba-Mo yields [4]. [1] Data extracted using the NNDC On-Line Data Service from the ENSDF database, file revised as of June 24, 2016. M. R. Bhat, Evaluated Nuclear Structure Data File (ENSDF), Nuclear Data for Science and Technology, page 817, edited by S. M. Qaim (SpringerVerlag, Berlin, Germany, 1992). [2] Experimental Unevaluated Nuclear Data List, http://www.nndc.bnl.gov/xundl. [3] Private communication from Vanderbilt University [4] S.-C. Wu \textit{et al.}, Phys. Rev. C \textbf{62}, 041601(R) (2000).   

Accuracy of Determination of the Parameters of Exotic Nuclei Nuclear Density Distributions in the Glauber Model

Parameters of a nuclear density distribution for an exotic nuclei with halo or skin structures can be determined from the experimentally measure interaction cross-section. In the presented work, to extract parameters for a halo and core, we compare experimental data on interaction cross section with reaction cross-sections calculated using expressions obtained in the Glauber Model and its optical approximation. These calculations are performed using Markov Chain Monte Carlo algorithm. In addition, we discuss the accuracy of the Monte Carlo approach to calculating the interaction and reaction cross-sections. The dependence of the accuracy of the density parameters of various exotic nuclei on the “quality” of the random numbers chains (here, “quality“ is defined by lag-1 autocorrelation time of a sequence of random numbers) is obtained for the Gaussian density distribution for a core and the Gaussian density distribution for a halo.