Session DA: CEU Poster Session

Real Photon Physics at MAMI

The scientific program at the Mainz Microtron (MAMI) is based on polarized electron and photon beams from the MAMI A-B-C accelerator complex with energies up to 1500 MeV. In order to deal with the energy increase, the photon tagger system has been extended and refurbished by the Glasgow University Nuclear Physics Group. It is now available for real photon experiments in the A2 hall. The Crystal Ball detector is being used regularly together with an inner detector for tracking and a forward crystal calorimeter (TAPS) for 4$\pi \quad \gamma $ coverage. A new data acquisition system with high-rate performance is in operation. Experiments are currently running using a liquid hydrogen/deuterium target. A cryogenic polarized frozen-spin target to be used in the Crystal Ball is near completion and will soon be used to provide polarized protons and deuterons (for polarized neutron experiments). A polarized Helium target is also under development. In this poster, we will present the current status of the experimental equipment and the role of student involvement in the experimental real photon program at MAMI.   

Neutron Energy Spectra for Deuteron Beams Incident on Thin Targets

Neutron energy spectra and cross-section data have been measured for deuteron breakup on thin targets using the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. Data was collected for tantalum and titanium targets at deuteron energies 20, 29, 35 and 38 MeV. Using a NE213 liquid-scintillation counter with neutron/gamma pulse shape discrimination, energy spectra were determined at zero degrees by measuring the time-of-flight relative to the cyclotron R.F. Additional data was collected at larger angles for deuteron energy of 20 MeV. The data collected tests the predictions of current breakup models, aiding in further development of the codes providing a better understanding of the competition between Coulombic and nuclear breakup. Breakup systematics will be useful in exploiting deuteron breakup as a mechanism for fast neutron production for a variety of applications.   

Digital Timing Algorithm for High Purity Germanium Detectors

The next generation of $\gamma $-ray detector arrays will be composed of large volume high purity germanium (HPGE) detectors that are electronically segmented. These detectors will be able to track $\gamma $-rays as they Compton scatter within the crystal and between adjacent crystals, eliminating the need for Compton suppression detectors and improving angular resolution. The new arrays will have much higher sensitivity, but require a shift from analog signal processing (ASP) to digital signal processing (DSP). The scope of the current project is to test the resolution of digital timing algorithms, a critical component of any $\gamma $-ray tracking system. A $\gamma -\gamma $ coincidence experiment was performed with a 60Co source and two small volume HPGE detectors using the Digital Data Acquisition System at the National Superconducting Cyclotron Laboratory. The resultant digitized waveforms were analyzed using multiple algorithms. These included digital models of ASP leading edge and constant fraction discriminators, and simple novel digital techniques..   

Angular Correlations in $^{96}$Mo

Gamma-gamma coincidences from $^{96}$Mo were detected by the OSIRIS cube spectrometer at the University of Cologne's FN Tandem Accelerator, to identify low-lying M1 transitions between 2+ states using angular correlations. Preliminary analysis of the low energy 2+ to 2+ cascades will be presented. This work was supported by NSF 0555665, Jeffress Fund J-809, and USDOE DE-FG02-91ER-40609 grants.   

The One-Neutron Knockout Reaction $^{9}$Be($^{44}$S,$^{43}$S)\textit{X}

We studied the structure of the exotic isotope $^{43}$S produced in the one-neutron knockout reaction $^{9}$Be($^{44}$S,$^{43}$S)\textit{X}. The experiment was conducted at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. We measured gamma-rays emitted by the excited $^{43}$S nuclei produced in the reaction using the Segmented Germanium Array (SeGA). We extracted the knockout cross sections for the reaction and used a GEANT simulation of SeGA to fit our measured gamma-ray spectrum. An expanded level scheme is proposed. We also analyzed the momentum distributions of the knockout products in order to determine the orbital angular momentum of the neutron removed during the reaction.   

A study of systematic uncertainties in the Daya Bay Neutrino Experiment

The Daya Bay Experiment is designed to set a precise upper limit for, if not pin-point, the value of the $\theta _{13}$ neutrino oscillation parameter. As shown in the parameterized PMNS matrix, accurate knowledge of $\theta _{13}$ will enable the study of CP violation in the lepton sector, in addition to supporting the theory of neutrino oscillation. This experiment seeks great precision by utilizing four detector sites; each site will house two Ga-laced liquid scintillator anti-neutrino detectors which first measure a prompt signal from the electron-positron annihilation following the inverse beta decay of anti-neutrinos, and second, identify a delay signal created by the subsequent neutron capture. This method, and the interchangeability of the detectors, greatly decreases the systematic uncertainty; however, the critical nature of systematics in reactor neutrino experiments warrants careful study. This poster will examine Daya Bay from a systematics perspective, producing a comparison with the Double Chooz experiment and setting a precision level for measurements of $\theta _{13 }$as a function of run-time and mass, as well as for a variety of active detector combinations. This preliminary work, using GloBES, will serve as a starting point for a more thorough analysis of Daya Bay's sensitivity limit.   

Extraction of Yields for Neutral Meson Photoproduction from the Proton and $^{3}$He with the CLAS Detector at Jefferson Lab

The photoproduction of $\pi^{0}$ and $\eta$ mesons from hydrogen and $^{3}$He targets over an incident photon energy range of 0.5 - 1.5 GeV is being studied using data from the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. This is part of a systematic study of meson photoproduction from the proton and light nuclear targets to investigate possible nuclear medium modifications of nucleon resonances and meson-nucleon interactions. The neutral mesons are reconstructed from their two-photon decay. Two- photon invariant mass spectra binned in incident photon energy and production angle are fitted to extract yields for $\pi^{0}$ and $\eta$ meson photoproduction. Monte Carlo simulations are also being performed to determine the acceptance of the CLAS detector for these reactions. The analysis will be described and the procedures used to extract the yields and determine the acceptance will be discussed.   

Impact of Nuclear Physics Uncertainties on Big Bang Nucleosynthesis Constraints on the Baryonic Matter Density

The total amount of baryonic (``normal'') matter in the Universe can be constrained by comparing the primordial abundances of $^2$H, $^4$He, and $^7$Li inferred from observations to the abundances predicted by the standard Big Bang Nucleosynthesis (BBN) theory. The centroid of this constraint depends on the input thermonuclear reaction rates responsible for the light element production in the early Universe and on the abundance observations. The width of the constraint is determined from the uncertainties in the observations, and by uncertainties in abundance predictions as determined by Monte Carlo BBN calculations in which thermonuclear reaction rate uncertainties are used.\footnote{M. S. Smith {\em et al.}, Astrophys. J. Suppl. {\bf 85} (1993) 219.} We have performed BBN Monte Carlo simulations wherein the reaction rate uncertainties are systematically reduced, to determine the impact that future nuclear physics measurements could have on the baryonic matter density constraint. The calculations were performed with the new suite of codes available at bigbangonline.org. Results of the simulations and their implications for future nuclear physics measurements will be presented. This research is supported by the USDOE.   

The Development of a Cosmic Ray Veto System

There are many experiments dedicated to the investigation of neutrino characteristics, such as the Majorana neutrinoless double-beta decay measurement, the Karlsruhe Tritium Neutrino Experiment, KATRIN, and the SNO solar neutrino experiment. Although the various neutrino experiments differ, they all must limit background interference because of the small numbers of events and/or the intervals of energies to be detected. At the University of Washington's Center for Experimental Nuclear Physics and Astrophysics (CENPA) an EG{\&}G germanium detector and shield has been constructed to allow preliminary radioassay of materials to be used in neutrino experiments. The detector is enclosed in lead to shield from environmental low energy radiation, and includes a scintillator veto system to eliminate cosmic rays from data. This system also serves as a developmental opportunity for Majorana R{\&}D allowing the characterization of the germanium detector digitization electronics and analysis software.   

Unstable Quantum Systems Coupled Via Continuum and Super Radiance

Exited states of a quantum system are unstable and decay into the continuum. The dynamics of a of a quantum signal through a two dimensional lattice with open decay channels coupled to the continuum is treated by means of this discretized effective non-hermitian Hamiltonian. The energies and widths are treated as real and imaginary parts of complex eingenvalues for the effective Hamiltonian. Coupling through the continuum reorganizes the dynamics of the system, as a result the energy widths of the intrinsic states are redistributed and very broad states are formed absorbing a significant part of all the summed energy widths. As a result these broad, super-radiant states become highly unstable, with short lifetimes, while the remaining states become trapped and long lived. This notion of super radiance was suggested by Dicke, over fifty years ago, for systems pertaining to coherent states in quantum optics, much later was it realized that the mechanism of super radiance arises in many other areas of physical phenomena in atomic, nuclear and particle physics. A sharp, sort of phase transition, between weak and strong coupling to the continuum is considered. The weak coupling limit corresponds to isolated sharp resonances, whereas strong coupling corresponds to the collectivization of widths and the formation of the short lived Dicke states.   

Cosmic Test Stand Development for PHENIX Muon Trigger Upgrade

The PHENIX experiment at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory will measure the flavor dependent quark and anti-quark polarizations in the proton. In proton-proton collisions a quark and anti-quark interaction can be signaled by the formation of a W-Boson. At PHENIX, W- Bosons are detected through the presence of a high transverse momentum muon. The current level 1 trigger for single muons makes only a minimum energy cut of about 2 GeV and this results in data rates that far exceed the bandwidth capabilities of the data acquisition system. To rectify this, an upgrade to the current muon trigger is underway that will trigger only on high transverse momentum muons using new resistive plate counters (RPC). Before these RPCs will be installed in the PHENIX spectrometer, their quality will be certified through the use of a cosmic muon test stand. This test stand will consist of a plane of hodoscopes on top and bottom as triggers with 10 RPCs in between. The efficiency and spatial resolution of these RPCs will be measured. This poster will illustrate this testing process.   

Heavy Meson Dynamics in Ultra-Relativistic Heavy-Ion Collisions

Heavy-ion collisions measured at RHIC have produced a novel state of ultra-high temperature and density matter called the strongly interacting Quark-Gluon-Plasma (sQGP). One of the most anticipated new measurements at RHIC centers on hadrons containing heavy quarks (i.e. charm/bottom quarks). These quarks are produced in form of charm-anticharm and bottom-antibottom pairs in hard pQCD interactions early in the time-evolution of the collision. In the absence of a QGP they would hadronize to form charmonium or bottonium states(i.e. J/Psi). However, color screening in the QGP may lead to suppression of such states -one observes the formation of D and B meson. The knowledge of the reaction dynamics of J/Psi and D mesons in the late hadronic phase of a heavy-ion reaction is crucial for the understanding of properties of the QGP and properties of heavy-quarks propagating through. For our analysis we employ a hadronic transport model, UrQMD, into which we have incorporated heavy-meson rescattering cross sections. We present an analysis of D meson and J/Psi collision rates, spectra and yields in the framework of the model and discuss their implications for measurements at RHIC.   

Testing Scintillator Efficiency for Use in RPC Test Stand for PHENIX at RHIC

The PHENIX experiment at RHIC is a large-scale detector for the study of polarized proton-proton collisions and heavy ion collisions. An upgrade to the muon trigger is being constructed. This upgrade is necessary for a detailed study of W-boson particles. It will selectively trigger on high transverse momentum muons only and not on the low transverse momentum muon background. By reconstructing W-boson particles, new insight into the spin structure of a proton will be gained. Resistive Plate Chambers (RPCs) will be used in the trigger upgrade. An ``RPC factory'' is being setup to build and test the RPCs. In order to test the RPCs we will be using a cosmic ray test stand in which hodoscopes are used as triggers. The hodoscopes are being built and tested for efficiency this summer. The efficiency of the hodoscopes is essential to the testing of the RPCs. Testing the RPCs in the cosmic ray test stand will be a time consuming process and without efficient hodoscopes as triggers the testing time will be significantly lengthened. By implementing a data acquisition system for the testing and use of the hodoscopes we are able to easily calculate efficiencies of the scintillators used to construct the hodoscopes. The methods, setup, and results for scintillator efficiency will be presented.   

Focal Plane Scanning Detector for Qweak

The Qweak experiment at Thomas Jefferson National Accelerator Facility will precisely measure the weak charge of the proton through parity-violating electron-proton scattering. Large-area \u{C}erenkov detectors will be operated in integrating mode to sense the scattered electrons. Tracking studies such as Q$^{2}$ determination and physics backgrounds will be performed at beam currents below 100nA, where tracking detectors are operable. However, the parity-violation experiment must be conducted at 180$\mu$A in order to achieve the statistical goal of the experiment. We are constructing a scanning detector with small fiducial area to facilitate the extrapolation from low to high beam currents. The scanning detector will use two light guide tubes in coincidence to eliminate background. To scan in the focal plane, the scanner and will be mounted on a robotic 2D motion assembly. Background and accidental coincidence rates on the detector were simulated, and a laser position detection system for the robotic assembly was designed and constructed. The results of these projects and the current status of the scanner will be discussed.   

Application of Different Similarity Renormalization Group Transformations to Nucleon-Nucleon Interactions

Using a Similarity Renormalization Group (SRG) transformation, Hamiltonians are driven to a band-diagonal form in momentum representation, with the low energy and high energy parts decoupled. Several different SRG transformations are applied to a wide range of realistic nucleon-nucleon interactions. The rate at which these potentials converge towards the diagonal and the degree to which high and low energies decouple are explored using two-body scattering and few-body bound state calculations. The results for these SRG evolution schemes are also compared to the results of the $V_{{\rm low} k}$ method.   

Improvements of the Focal Plane of SASSYER

The Small Angle Separator System at Yale for Evaporation Residues (SASSYER) at Yale University is a gas-filled recoil separator, specializing in the investigation of the production and the structure of nuclei heavier than $^{208}$Pb. New instrumentation for the focal plane of SASSYER under development at WNSL at Yale will replace the previous equipment with a compact chamber for double-sided silicon detectors (DSSD). Here we are reporting on improvements of the focal plane of SASSYER, including DSSD electronics, a detector cooling system, and ion optics tests. MUX-16 boards from MESYTEC, 16 channel multiplexed amplifiers, were tested and quantified. An alcohol cooling system, related to the DSSD, was characterized. The ion optics tests extracted effective magnetic rigidities of the separator. Results of the tests will be presented. This work was supported by the NSF grant PHY 0555665, Jeffress Fund J-809, and USDOE grant DE-FG02-91ER-40609.   

Neutron Single Particle Strengths in Z=20,22,24 Isotopes

Spectroscopic factor (SF) is one of the most fundamental quantities in nuclear physics. It provides the information of the single particle strength of different states in a nucleus. In the present work, a consistent analysis developed in ref [1] is used to extract SFs for nuclei with $^{40}$Ca core. We examine the evolution of the single particle states in $^{41,} $$^{43,}$$^{45,}$$^{47}$Ca to understand how the description of the shell model evolves from \emph{N}=20 to \emph{N}=28 closed shell. While the ground states of the Ca isotopes are well described by the simple shell model consisting of valence nucleons and an inert $^{40}$Ca core, our analysis suggests that excited states of these nuclei cannot be described so simply because of significant fragmentation of the single particle strength. The fragmentation is more obvious when we compare the \emph{N}=27 nuclei of $^{47}$Ca and $^{51}$Cr. Similarly, we see the fragmentation of the levels increases when more protons are added to the $^{40}$Ca core in the \emph{N}=29 region for $^{47}$Ar, $^{49}$Ca, $^{51}$Ti and $^{53}$Cr nuclei. In the poster, comparisons of the experimental and the shell model predicted levels and spectroscopic factors will be presented. Reference: [1] M.B.Tsang et. al., Phys. Rev. Lett. {\bf{95}}, 222501 (2005).   

Study of Instrumental Asymmetries in Focal Plane Polarimeter

Proton recoil polarization has been measured in the quasi-elastic $^4$He$(\vec e,e' \vec p)$ reaction at $Q^2 = 0.8$ and 1.3 (GeV/$c$)$^2$ in Jefferson Lab experiment E03-104. The induced polarization of the recoiling proton is a measure of the proton's final state interactions (FSI), and precise measurements are needed to constrain theoretical calculations. The proton polarization is extracted from asymmetries in angular distributions measured in the focal plane polarimeter (FPP) of the Hall A High Resolution Spectrometer. The process of extracting the induced polarization becomes complicated due to the presence of instrumental asymmetries in the FPP. Systematic studies of the detector response have shown inefficient regions in the FPP straw chambers. A novel technique for the extraction of induced polarization has been created in efforts of including only those proton tracks where the detector is equally efficient for both azimuthal angles $\phi$ and $\phi + \pi$, respectively. The procedure and results will be presented and described.   

Preliminary CLAS 12 Simulation Analysis and Optimization

Jefferson Laboratory (JLab) is undergoing an upgrade to increase beam energy from 6 GeV to 12 GeV to more clearly understand hadronic structure and quantum chromodynamics. The existing detector in Hall B is being upgraded to take advantage of the new physics opportunities. The new detector, CLAS 12, is in the design phase and we are developing a new simulation package, Sim12. The new code uses at least eight specially configured software packages to run, requiring extended compilation and configuration times. This installation procedure was optimized and documented resulting in a far shorter installation time. Sim12 is resource intensive, hence optimization was performed to decrease initialization times, accommodate the large amount of vertices necessary to represent the detector, and to decrease processing times of simulations. To accommodate event generators, which are necessary for experimentally relevant simulations, utilities to input event files were created. Finally, preliminary analysis was performed on Monte Carlo generated data.   

Dual-axis, Duo-lateral Position Sensitive Detectors

Over the years, a variety of approaches have been used to determine the position of a particle measured by a silicon detector. Discrete detectors require many channels of electronics to achieve good position resolution. Another avenue is to use a resistive detector, which measures the position by charge splitting. Resistive tetra-lateral detectors can be used to achieve both horizontal and vertical position. However, these result in some distortion in the signal requiring a complex algorithm for correction. Our solution to this challenge was to work with Micron Semiconductor to develop a new, state of the art, detector- now known as the Dual-axis, Duo-lateral Position Sensitive Detector, or simply, a DADL PSD. With the DADL PSD, both sides of the detector are used to obtain the energy of incoming particles. Resistive Strips help to guide the charge produced by the incoming particles across the detector to the collecting edges to be used as signal. Guard rings are in place to minimize leakage current, thereby maximizing resolution. The DADL PSD has achieved both excellent position and energy resolution. Results from both source tests and online data will be presented.   

Identification of Upsilon Particles Using the Preshower Detector in STAR

The STAR detector, located at Brookhaven National Laboratory is used for investigating relativistic heavy ion collisions and the possible formation of a new state of matter, the Quark Gluon Plasma (QGP). The suppression of heavy quarkonia, such as J/Psi and Upsilon particles, can be an important sign of the QGP. The J/Psi signal is complicated by the fact that some recombination is also expected in the QGP. The heavier Upsilon particle is interesting because it is not thought to experience recombination at RHIC energies. This poster will investigate attempts to reconstruct the Upsilon signal using a background subtraction method. STAR's Barrel Electromagnetic Calorimeter (BEMC) has a Barrel Preshower detector (BPRS) which facilitates the identification of the electrons over a hadronic background. We will look at work done in commissioning the BPRS, its effectiveness in reducing hadronic background in the calorimeter, and how this background reduction influences Upsilon identification.   

Modeling a Carbon Diagnostic System Using MCNPX

MCNPX is currently being used to model various carbon diagnostic configurations for use at OMEGA with plans to design a similar system for the National Ignition Facility (NIF). The purpose of such models is to optimize the carbon diagnostic's detection of signature products (i.e. tertiary neutrons) from a self-sustaining inertial confinement fusion (ICF) implosion. Results will be presented.   

Development and Testing of $Q^p_{Weak}$ Luminosity Monitors

Building on advances in recent parity experiments at Jefferson Lab, the opportunity exists to make the first precision measurement of the weak charge of the proton, $Q^p_{Weak}$. The $Q^p_{Weak}$ experiment will measure the asymmetry in the scattering of longitudinally polarized electrons on a liquid hydrogen target. The luminosity monitors, placed at forward scattering angles, will be used for monitoring sources of false asymmetry and target density fluctuations. The luminosity monitors will consist of an array of Cerenkov quartz coupled to photomultiplier tubes by air light guides. It is therefore essential to quantify the linearity of the response of the luminosity monitor PMTs. This is being tested with a small asymmetry and a complete electronics chain designed to mimic experimental conditions. Additionally, the air light guides are being constructed and tested for transmission efficiency using cosmic ray events incident on the quartz Cerenkov radiators.   

Jet Measurements for QGP Experiments at CMS

Since the 1980s, experimentalists have sought to create in heavy ion collisions a new form of matter called quark-gluon plasma (QGP), where the constituent quarks of highly energetic hadrons become deconfined amidst large quantities of gluons. Measurements of the QGP can serve not only as a test of non-perturbative aspects of quantum chromodynamics, but also illuminate the properties of the early universe, which is believed to have existed as a QGP at the first few microseconds after the Big Bang. We propose a new measurement with the Compact Muon Solenoid at the Large Hadron Collider that uses the dileptonic decay of Z$^{0}$ bosons to tag jets electromagnetically. Dileptons are unhindered by the QGP's strong color field, and thus allow for direct, model-independent measurements of jet energy loss. I will present first studies of experimental feasibility of measuring the Z$^{0}$ signal and identifying the associated background.   

Effects of High Count Rates and Pulse Pileup in Sodium Iodide Scintillation Detectors

Radiation Portal Monitors (RPMs) are a key component for interdicting illicit radioactive material at US border crossings. PVT detectors have been central to this effort, however they lack the capability to identify specific radioisotopes, resulting in the development of NaI detectors that produce a higher resolution spectrum. An experiment was performed using 57Co, 60Co and 137Cs sources to determine the effects of high-count situations and pulse pileup on the spectral profile created by ASPs. Attention was focused on the common spectroscopic problems of peak shifting, count-rate saturation and distortion of spectral features. In these situations, isotope identification algorithms may experience problems such as additional or different sources being detected, or failure to recognize present isotopes. Experimental results were compared to MCNP simulations of the data. One of the ASPs tested has some compensation for high-count effects, and does not show these effects. The other ASP displayed signs of peak shifting but very little evidence of spectral marring. The NaI logs however, exhibited spectral distortion and peak shifting under conditions of pulse pile-up. These results provide foundational information in assessing how these detectors respond to potential saturation scenarios.   

Parallel plate ionization chamber in low pressure helium gas

A parallel plate ionization chamber was constructed for beam intensity monitoring. The chamber is placed in a gas-filled volume 1.5m upstream from the gas-filled separator SASSYER. Its output current will be used to determine absolute reaction cross sections. In a dedicated test experiment with a 100 MeV $^{32}$S beam and an applied potential of 300V, the signal current had an average standard deviation of 0.4{\%}, and demonstrated a linear relationship (R$^{2}$ = 0.9894) with the beam intensity. Also, at an intensity of 6 particle nanoamperes, the current exhibited a linear dependence (R$^{2}$ = 0.9813) on voltage, indicating that the chamber was operating in the proportional counter region. Our results agreed well with predictions made using extrapolated Townsend coefficients, though we observed a constant systematic and constant deviation between these estimates and our output current. This work was supported under US DOE grant number DE-FG0291ER-40609 and the Yale College Dean's Fellowship for Research in the Sciences.   

Biases in Peak Fitting for Low-Statistics Data

In many areas of physics, the result of a measurement is a peak (signal) on top of a background (noise). For example in nuclear physics, the energies and intensities of \begin{math} \gamma \end{math}-rays emitted by excited nuclei are important experimental observables. To extract this information from measured energy spectra, the peaks that correspond to the detection of de-excitation \begin{math} \gamma \end{math}-rays are fitted with mathematical functions, for example with Gaussians. When a mathematical function is fitted to experimental data, the fitting method may introduce a significant bias on the estimated parameters. This is particularly important for low-statistics data, in which case the possible biases must be determined since they might introduce large uncertainties. In present work, Monte Carlo simulations of Poisson distributed data of a Gaussian peak with an exponential background are fitted with different methods and the results are compared to the true spectra to determine the biases. The different fitting methods analyzed with respect to the Gaussian peak and background involve \begin{math} \chi^2 \end{math} statistics and maximum likelihood methods. The Monte Carlo analysis shows a significant bias of the peak fitting for one of the most important parameters, the area of the peak.   

Parameterization of Polarized $^{3}$He Quasi-Elastic Scattering Cross Sections

Radiative corrections are important steps when extracting scattering cross sections from data. In order to apply radiative corrections to the $^{3}$He nucleus, an accurate parameterization of these cross-sectional data in a wide kinematic range are needed. There exist no world parameterizations for the polarized quasi-elastic scattering cross-sections for the $^{3}$He nucleus, but instead data from other nuclei are combined with theoretical predictions for the polarized $^{3}$He nucleus. However, $^{3}$He nuclear effects are neglected. This can lead to large uncertainties in the results. In order to perform the parameterization, various computational methods were used to create a physical model of the scattering which would not neglect the $^{3}$He nuclear effects. The Jefferson Lab National Accelerator Facility data were fit to various nonlinear distribution models and the best fits were found for each beam energy. A global fit was created by fitting the parameters of these distributions. These results can be used to predict polarized quasi-elastic cross sections for unmeasured kinematics and for applying radiative corrections where such parameterizations are needed.   

Determining Neutron Multiplicity in MoNA

The Modular Neutron Array, located at the NSCL at Michigan State University, is used in conjunction with the MSU/FSU Sweeper Magnet to study the breakup of neutron-rich nuclei. Fragmentation reactions create particle-unstable nuclei near the neutron dripline which spontaneously breakup by the decay of one or two neutrons with energies that reflect the nuclear structure of unbound excited and ground states. The neutrons continue forward into MoNA where their position and time are recorded, and the charged fragments' position and energy are measured by the array of detectors following the Sweeper Magnet. The neutron decay energies can then be determined using kinematic reconstruction of the breakup. It is important to distinguish between one- and two-neutron decays in MoNA. We have therefore developed an algorithm that helps determine neutron multiplicity, based on energy and momentum conservation restrictions for single neutrons scattering multiple times in MoNA. Results of this approach to the analysis of $^{12}$Be and $^{11}$Be decay will be presented.   

Parity Measurements in $^{79}$Sr and $^{80}$Y

Recently, a band suspected to be based on the [431]1/2$^{+}$ configuration in $^{79}$Sr has been shown to correspond to a very highly-deformed shape, but the parity of this band has never been measured directly. The yrast band in $^{80}$Y is expected to have positive parity based on theoretical calculations and systematic evidence collected from other neighboring nuclei, but this also has not been confirmed experimentally. Therefore, the goal of this investigation was to measure conclusively the parity of these bands in $^{79}$Sr and $^{80}$Y. The $^{79}$Sr and $^{80}$Y nuclei were produced at Florida State University following the $^{28}$Si + $^{54}$Fe fusion-evaporation reaction at 90 MeV. The linear polarization of $\gamma$ rays that were emitted from $^{79}$Sr and $^{80}$Y following the reaction were measured based on how they preferentially Compton-scattered in three Clover detectors. From these measurements, the known parity assignments in $^{79}$Sr were verified, but conclusive parity assignments could not be made for the proposed [431]1/2$^{+}$ band. However, a firm assignment of positive parity was made for the yrast band in $^{80}$Y, showing that this nucleus is similar in this regard to its odd-odd neighbors.   

Precise $\alpha_{K}$ Measurement of 346.5 keV Transition in $^{197}$Pt as a Test of Internal Conversion Theory

We have determined the K-shell internal conversion coefficient (ICC) of the 346.5 keV M4 transition in $^{197}$Pt using an HPGe detector at the Texas A\&M University Cyclotron. ICCs are used in the study of nuclear decay schemes, branching ratios and transition rates, as well as spin and parity assignments. We have recently been measuring ICCs (in $^{193}$Ir , $^{137}$Ba, $^{134}$Cs) with the specific purpose of testing the method used to treat the atomic vacancy in calculating ICCs. Previous measurements of the ICC for the 346.5 keV transition in $^{197}$Pt have disagreed significantly from calculated coefficients regardless of the method used to consider the vacancy. This could have indicated some other unknown factor causing a problem in the calculations. Our preliminary result, determined with an uncertainty of 3\% is $\alpha_{K}$= 4.24(13). This disagrees with previous measurements ($\alpha_{K}$= 4.02(8)) and is now consistent with the calculated ICCs.   

Neutron-Induced Partial Cross-Section Measurements on $^{76}$Ge Motivated by The Majorana Project 0$\nu\beta\beta$ Decay Search

The goal of the Majorana Collaboration is to study 0$\nu\beta\beta$ in order to verify that the neutrino is its own anti-particle; and if so, what is the mass ofthe electron neutrino. Observation of a sharp peak at the $\beta\beta$ endpoint energy will confirm 0$\nu\beta\beta$ as a decay mode, and determination of the partial width will determine the matrix element which depends directly on the electron neutrino mass. In order to observe and verify the existence of 0$\nu\beta\beta$, it is important to reduce intrinsic, extrinsic,\& cosmogenic backgrounds. The Majorana Project will operate with HPGe detectors deep underground to achieve a low-background environment. Recent advances in signal processing and detector design have also enabled scientists to further understand background sources. $\gamma$-ray spectra from the interaction of pulsed mono-energetic neutrons with $^{76}$Ge were measured at TUNL using segmented HPGe clover detectors. The neutron-induced partial cross-sections for $\gamma$ transitions in $^{76}$Ge were measured at E$_n$ = 8 and 12MeV.   

PDF Contributions and Parity Violation at High Bjorken x.

In recent decades, leptonic deep inelastic scattering (DIS) has been widel y used to probe nucleon structure. Despite remarkable success, studies of parton contributions to nuclear structure and behavior have complicated t he original picture of a quark-dominated nucleon. Beyond issues of quark -parton contribution to nucleon spin, high precision data characterizing t he d-quark parton distribution function (PDF) at high values (i.e. $\geq$ 0.7) of the Bjorken parameterization remain incomplete. Calculations of the d/ u PDF ratio contribution to parity-violating asymmetries in un/-polarized DIS are performed for a range of values of the square momentum transfer $Q ^2$; for completeness, calculations involve several PDF models and target /polarization schemes for the neutral/electromagnetic interference current. So far, calculations predictably demonstrate a significant dependence o f beam asymmetries upon the d/u PDF ratio. These results for d/u are expa nded by similar findings for the dependence of the polarized, target asymm etry upon the spin-dependent PDF ratio $\frac{\Delta d}{\Delta u}$. Thi s evaluation of PDF effects through d/u and $\frac{\Delta d}{\Delta u}$ co ncurs with and expands earlier findings in nucleon structure, thereby driv ing further interest and tests of the Quark-Parton Model (QPM) and parity violation.   

One Proton Knockout from a Relativistic $^{45}$Cl Ion Beam

The single particle structure and behavior of $^{44}$S was analyzed through one-proton knockout conducted at the National Superconducting Cyclotron Laboratory at Michigan State University. A fast beam of $^{44}$S fragments was produced from the one-proton knockout reaction $^{9}$Be($^{45}$Cl, $^{44}$S)X. The excited $^{44}$S particles emitted gamma rays that were collected by the Segmented Germanium Array (SeGA). The measured gamma-ray spectrum of $^{44}$S was fitted with GEANT simulations of the gamma-ray response of SeGA in order to extract gamma-ray intensities. A proposal for the level scheme of $^{44}$S will be presented. Knockout cross sections were measured and the momentum distributions of the recoiling $^{44}$S nuclei were analyzed to determine the orbital angular momentum of the proton knocked out.   

Ion Optic Simulation of Ion Source and Beam Transport for Isotope Separator at HRIBF

To conduct decay spectroscopy experiments on isobarically pure sources, a compact high resolution ($>$15,000) isobar separator is being designed and built. The device is based on the Multi-Pass Time-of --Flight (MTOF) principle and the separation feature is realized by a fast electrostatic Bradbury-Nielson gate\footnote{ Bradbury, N.E.; Nielsen, R.A. Phys. Rev.1936,49, 388-393}. MTOF mass separator (MS) will be coupled to the on-line isotope separator UNISOR at HRIBF. In order to design appropriate injection optics for MTOF MS, we need to know the properties of the incoming beam, namely the beam emittance and center position. Therefore, we use the 3D simulation code SIMION 8.0 to study the ion extraction within an Electron Beam Plasma ion source, and the beam transport through an extractor and a focusing lens system. The beam simulation and analysis code COSY INFINITY is used to trace the extracted beam through the UNISOR beam line until the position where MTOF MS will be installed. This study evaluates the sensitivity of final beam phase space distribution on initial conditions. Possibilities of adjusting the ion source and beam line settings to get desirable beam parameters at the entrance to MTOF MS are investigated.   

High Voltage Breakdown and SQUID Performance for the Neutron Electric Dipole Moment Experiment

A new search for a permanent electric dipole moment (EDM) of the neutron is underway at the Oak Ridge Spallation Neutron Source. A non-zero EDM would be a signal of time reversal symmetry violation and improve our understanding of the matter-antimatter asymmetry of the universe. The experiment will use a Superconducting Quantum Interference Device (SQUID) to infer the precession of ultracold neutrons held in a superfluid helium bath, in the presence of applied electric and magnetic fields. The experiment's sensitivity is proportional to the applied electric field. Neither the maximum practical size of the electric field nor the behavior of SQUIDs in proximity to this field are presently understood. Therefore we have constructed a small prototype (to decrease the cool-down time) to verify that SQUIDs can function in a high voltage environment and when exposed to RF interference. Another goal is to determine what characteristics allow us to maximize the electric field without breakdown. To do this we measure the breakdown voltage in both normal and superfluid helium at a variety of temperatures and (more uniquely) at different pressures, as well as test a variety of electrode materials.   

Database Design and Data Retrieval for the PHENIX RPC Factory

Database Design and Data Retrieval for the PHENIX RPC Factory Justine Ide, Muhlenberg College, PHENIX Collaboration -- One of the primary goals of the PHENIX experiment, located on the accelerator ring of the Relativistic Heavy Ion Collider (RHIC), is to determine how the components of a proton contribute to its total spin. In particular, the muon trigger upgrade is designed to allow us to determine the flavor separated quark and antiquark polarizations of the proton. We will achieve this by enhancing our ability to trigger on high transverse momentum single muons that result from the decay of W bosons produced in polarized proton-proton collisions at RHIC. Resistive Plate Chambers (RPCs) will play a pivotal role in the upgrade, and much of last summer was devoted to creating an RPC factory to build and test the new subsystem. A database was constructed in order store the data for numerous quality control tests, as well as information about environmental conditions, and the location of, the gas gaps and modules. This archived information will be used to select the best gas gaps during construction and will be useful during future data analysis. This poster will focus on the RPC factory database design and the retrieval of the stored information.   

Database for the PHENIX RPC Factory

The Pioneering High Energy Nuclear Interaction Experiment (PHENIX) is located on the Relativistic Heavy Ion Collider (RHIC) ring at Brookhaven National Laboratory. One of the goals of RHIC is to discover the origin of the proton spin. Resistive Plate Chambers (RPCs) will be used at PHENIX as a level 1 trigger to select single high transverse momentum muon events from a large background of low transverse momentum muon events. During the assembly of the RPCs, we will be keeping track of information from quality control tests, performance tests and the position each RPC will occupy in the detector. This information will be used for calibrations after the RPCs are installed in PHENIX. Therefore, the information needs to be organized and stored in such a way that it can easily be accessed over the next several years. This will be done through the use of a database that will be accessed both by a program which inputs data automatically from a number of systems and by a web interface that will be used both to input information and access that information at a later date. The structure of the database will be presented as well as the methods that will be used to input the information.   

Calibrating Scintillator position measurement for testing RPC modules for PHENIX at RHIC

PHENIX is a large, high-energy experiment at the Relativistic Heavy Ion Collider. One of PHENIX's many goals is to study the spin structure of the proton through observing W-boson decays from quark-anti quark interactions in polarized p-p collisions. An upgraded trigger system using Resistive Plate Chambers that are being built for PHENIX will increase the rejection factor of unfavorable events by two orders of magnitude so that this measurement is possible. As these RPCs are manufactured and assembled into larger sections for installation, an important step in quality assurance is testing each module in a cosmic ray test stand triggered by hodoscopes. These scintillators will also provide a position measurement, giving us positioning information in directions where the stacked RPCs have low spatial resolution. With careful timing calibration the information from the scintillators will enable us to test aspects of the RPC manufacturing that will lead to much higher quality monitoring. This poster will include methods and results from this positioning measurement.   

New Neutron Capabilities in the 88-Inch Cyclotron at Lawrence Berkeley National Lab (LBNL)

Two neutron generators - one 14 MeV and one thermal - will be installed at the 88-Inch Cyclotron at LBNL. The 14 MeV (d, t) source has an integrated neutron output of 10$^{11}$ neutron/sec at maximum power. The thermal source generates 10$^{7}$ neutrons/sec in a 116 cm$^{2}$ field. These neutron generators will be used in diagnostic studies and cross section measurements for the National Ignition Facility at LLNL, and will also be utilized for radiation effects testing. The project scope will be presented including facility layout, neutron flux, shielding calculations and timeline. This new capability will add to the versatility of the 88-inch cyclotron facility and provide exciting new opportunities for both basic and applied nuclear science and national space security missions.   

DIANNA: Modeling the time dependence of the YAGUAR reactor pulse

A direct measurement of the neutron-neutron scattering length, $a_{nn}$, can be found from thermal-thermal neutron collisions within the through channel in the aperiodic pulsed YAGUAR reactor. We model the reactor using MCNPX and the visualization code IViPP. Our geometries now include the 12m time-of-flight path, with its complex collimation system. In addition, we analyzed the time dynamics of the neutron field on the moderator wall. This knowledge of the pulse along with the collision modeling is necessary to extract $a_{nn}$ from the detector count rate.   

From RHIC to LHC: Elliptic and radial flow effects on hadron spectra

Using (2+1)-dimensional ideal hydrodynamics we investigate the elliptic flow and spectra of pions and protons in peripheral Au+Au collisions as a function of transverse momentum at midrapidity. We also set a hydrodynamic benchmark for $\pi ^{+}$/p, $\Lambda $/K$^{+}$, and $\Omega $/$\phi $ ratios as a function of transverse momentum. Energies of the collisions we investigate range from several GeV (AGS energies) to several TeV (LHC energies).   

How Many Degrees of Freedom are Required to Describe Baryon Resonances?

In quark models the number of baryon excited states predicted depends only on the number of degrees of freedom. Simplified quark-diquark models describe all the observed resonance states considerably well. However, standard 3-quark models have additional degrees of freedom that predict a greater number of excited states than have been observed. In order to solve the mystery of the ``missing baryons'', gain a better understanding of nucleon structure/dynamics and arrive at a consistent quark model, accurate data are essential. Recent proposed upgrades to the Main Injector Particle Production experiment (MIPP) at Fermilab will facilitate baryon spectroscopy by scanning the mass region from 1.5 to 2.5 GeV/c$^{2}$ while simultaneously measuring elastic and inelastic channels such as $\pi^- p \rightarrow \pi^+ \pi^- n$ and $\pi^- p \rightarrow K^0 \Lambda$. A description of MIPP will be presented, including proposed improvements to the DAQ, lower momentum capabilities, additional plastic ball backscatter detector and upgraded veto hodoscope, as well as the theoretical motivation and expected results.   

Proposed Radiation Effects Beam Line for the K150 Cyclotron

Solar flares, cosmic rays and the Earth's Van Allen radiation belts serve as natural sources of space radiation. Such ionizing radiation is potentially harmful to the semiconductor components found in space vehicles and orbiting satellites. Aerospace engineers test the performance and durability of space bound materials and semiconductor devices with accelerated beams of heavy ions produced at laboratories on Earth. The recently recommissioned K150 cyclotron at Texas A{\&}M University can provide accelerated beams similar to the ion species and energies experienced in space. A dedicated beam line has been proposed which includes a vacuum testing chamber and an in-air end station. The computer code ``Transport'' was used to determine the number of electromagnets needed and their optimal positions along the beam line so that both diffuse and focused beam spots can be produced at the target location. A list of ions at energies of 5, 14, 25A MeV/nucleon have been determined that will give experimenters sufficient range and linear energy transfer to test their semiconductor devices.   

Exploring Isomeric States near Doubly-Magic 208Pb

The shell model of nuclear structure involves calculating the energy levels of a nucleon in an appropriate attractive potential well. The levels follow a shell structure, with large energy gaps between shells. The number of nucleons required to fill a shell is referred to as a ``magic number''. Probing these shell gaps is an important objective of nuclear structure physics, as it tests and allows fine tuning of the potential well. One way to probe the single- particle levels is to examine metastable excited states, known as isomers, near these shell gaps. Using gamma-ray spectroscopy it is possible to deduce decay schemes and half-lives of these isomers, and subsequently infer information about the excitation mechanism and shell gaps. This project consists of establishing half-lives of isomeric stats in nuclei near 209Bi, which has one excess proton over doubly ``magic'' 208Pb. Excited states at high angular momentum were populated with the ATLAS accelerator facility at Argonne National Laboratory using a 209Bi beam incident on a 248Cu target. The Gammasphere detector array was used for data acquisition.   

Hohlraum Reactions as a NIF Diagnostic

In Inertial Confinement Fusion (ICF), a capsule containing fuel, typically deuterium and tritium (D-T), is compressed using a pulse of energy. At the National Ignition Facility (NIF), experiments will attempt to achieve ignition using an indirect drive apparatus in which a D-T capsule is placed inside a high-Z hohlraum in order to produce x-rays. One of the primary concerns for ICF is mixing between capsule and fuel, for which there does not currently exist a diagnostic at NIF. With an understanding of the effects of mix on the shape of the neutron spectrum, we can use several different reactions expected to occur within the hohlraum along with radiochemistry to infer some aspects of the neutron spectrum and hence make measurements concerning the level of mix taking place within the capsule. In addition, we may be able to make similar measurements for temperature, $<\rho $*r$>$, or $<\rho $*r$>$ asymmetry.   

Tailoring a target for transient field measurements of magnetic moments of short-lived excited states with radioactive beams

An understanding of target magnetization and kinematics is essential to determine $g$ factors using the Transient Field (TF) technique with Coulomb excitation of radioactive beams (RIB). With stable beams, layered targets of C/(Gd or Fe)/Cu are used. The Coulomb scattered C ions are detected in Si counters, located above and below the beam axis, in coincidence with $\gamma$-rays recorded in 4 Ge Clover detectors. With RIBs, the background from beam scattering is critical. For example, the $^ {132}$Te beam at ORNL contains $\sim10\%$ of isobaric $^{132} $Sb that decays via the $^{132}$Te, $4^+_1 \rightarrow 2^+_1 \rightarrow 0^+_1$, $\gamma$ cascade. Removing the Cu from the target greatly reduces the scattering of RIBs. Furthermore, with thinner ferromagnets, the $^{132}$Te ions decay in flight and the de-excitation $\gamma$-rays are Doppler shifted and easily distinguishable from the Sb unshifted background. While such a target without Cu backing does not provide sufficient cooling for a beam of 10$^9$ p/sec, it is adequate for a RIB of 10$^7$ p/sec. Results will be shown for both gadolinium and iron targets. Work supported by the US NSF and DOE.   

Gamma-Ray Spectroscopy of A$\approx $100 Nuclei

Structural evolution is often characterized as a function of nucleon number. When investigating a specific nuclide, structural evolution may be described as a function of angular momentum, referred to as the E-GOS (E-Gamma Over Spin) method. An experiment was performed using the ESTU tandem Van de Graff accelerator at the Wright Nuclear Structure Laboratory at Yale University. Several nuclei in the A$\approx $100 region were populated via the fusion-evaporation reaction $^{92}$Zr($^{12}$C,4n+$\gamma )^{100}$Pd. Subsequent gamma ray emissions were detected using the detector array SPEEDY, which is comprised of eight clover-leafed HP Ge crystal detectors. Data were collected at four different beam energies: 66, 68, 70, and 75MeV. The data will be interpreted utilizing the E-GOS method.   

Study of the Spent Fuel Contribution to the Reactor Antineutino Spectra Measured in the Daya Bay $\theta _{13}$ Experiment

The Daya Bay reactor neutrino experiment is a multi-national project to study neutrino oscillation by using the antineutrinos released by Daya Bay Nuclear Power Plant and Lingao Nuclear Power Plant in China. The aim of the experiment is to make a precise measurement of the neutrino mixing angle $\theta _{13}$ with a sensitivity of 0.01 in sin$^{2}$(2$\theta _{13})$ by measuring the flux and spectrum of electron antineutrinos. We study the variations of the nuclear fuel composition in the reactor and the resulting changes in the antineutrino flux contributed by each fissile isotope throughout the fuel burning process. Experimental data are used to determine parameterizations of the reactor antineutrino energy spectra. By using information on the varying fuel composition and the antineutrino cross-sections, we calculate the antineutrino spectra measured in the eight detectors in the Daya Bay experiment and compare them to the neutrino oscillation effect due to various values of $\theta _{13}$. The uncertainty on the measurement of sin$^{2}$(2$\theta _{13})$ due to spent reactor fuel is estimated.   

Main Injector Particle Production Veto Hodoscope Upgrade

The Main Injector Particle Production (MIPP) experiment at Fermi National Accelerator Laboratory (FNAL) has multiple goals which include: providing a starting point for the study of non-perturbative QCD and its associated baryon resonances, gaining a better understanding of the propagation of particles in nuclei, and to improve hadronic shower models in collider simulation programs such as Geant. Having completed its initial run, the MIPP experiment is again in the proposal stage to upgrade the detector in order to improve the data acquisition rate and to extend the measurements to lower momenta. During the original run, especially at low momentum, beam halo and spray particles hitting the experiment in coincidence with events of interest caused problems. The existing veto scintillator, a .3 x .3 m panel with a hole in the center for the beam to pass through, was found to be too small in the initial run and thus is rendered even less effective in the upgraded experiment due to the increase of beam intensity and background. Because of this problem a 1.8 x 1.2 m veto hodoscope has been constructed from eight 1.8 x .15 m Eljen EJ-200 plastic scintillators,with a notch in the two middle pieces to form a hole to allow the beam to pass through, and 16 photomultiplier tubes to replace the existing panel. The research, design, testing, and assembly of this wall will be presented.   

Decay of $^{10}$C excited states above the 2$p$ + 2$\alpha $ threshold and the contribution from ``democratic'' two-proton emission

The decay of $^{10}$C excited states to the 2$p$ +2$\alpha $ exit channel has been studied using an E/A = 10.7 MeV $^{10}$C beam inelastically scattered from a $^{9}$Be target. Levels associated with the two-proton decay to the ground state of $^{8}$Be have been observed. These include states at 5.18 and 6.54 MeV which decay by sequential two-proton emission through the long-lived intermediate state of $^{9}$B. In addition, states at 5.3 and 6.57 MeV were found in which there is no long-lived intermediate state between the two proton emissions. For the 6.57 MeV state, the two protons are preferably emitted on the same side of the decaying $^{10}$C fragment. Furthermore, preliminary evidence will be presented for an 8 MeV state decaying through the second excited state of $^{9}$B.   

Development and Tests of the LED Calibration System for the Daya Bay Reactor Neutrino Experiment

The Daya Bay reactor neutrino experiment must measure the neutrino rate and spectrum with very precision. Thus, the detector modules must be carefully calibrated in order to produce reliable data. This study consists of hardware research and development for the LED portion of the detector calibration system, for which a fast timing resolution is key. We used a photomultiplier tube and CAMAC DAQ to test possible components, including pulsing circuits, LEDs, coaxial cable, and an electrical slip ring. We produced a 4ns light pulse using a DEI PCO-7110 Laser Diode Driver Module and an Industrial Fiber Optics, Inc. IF-E92A 430nm LED in parallel with a 0.12$\mu$H inductor. We determined that the Moog, Inc. electrical slip ring does not significantly distort or widen the light pulse, and the Cooner Wire CW2040-3650F coaxial cable causes only a very small amount of pulse widening. Because these quick pulses are fast enough for use in the calibration system and because the slip ring and coaxial cable are satisfactory, these components are viable options for Daya Bay. Because these components are all commercially available, they would be simpler to use and possibly more reliable than custom-made components. Thus, we have demonstrated that these components are a good option, and we recommend them as the baseline of the LED calibration system for Daya Bay.   

HiRA CsI Detector Response to Low Energy Protons

In the upcoming experiment 05133 at the National Superconducting Cyclotron Laboratory at Michigan State University, the High Resolution Array (HiRA) will detect low energy protons in the range of 1-10 MeV. The HiRA has not previously been used to detect protons of this energy range. Therefore, the response of the CsI detectors to low energy protons must be analyzed. This will aid in the calibration of the detectors and contribute to their resolving capabilities. The testing of the telescopes will be performed using the tandem Van de Graaff Accelerator at Western Michigan University. A 10 MeV proton beam will strike a polypropylene (CH{\_}2) target, causing proton-proton elastic collisions. The scattered protons will be detected by the telescopes in an angular range of 10-50 degrees from the beam axis. The energies of the scattered protons are known from kinematic calculations for elastic collisions. Using these energies, the output voltages of the telescopes can be calibrated. In addition, the analysis of histograms in conjunction with the angular range of the detectors will measure the energy resolution of the HiRA telescopes for low energy protons.   

Parity Measurements in $^{80}$Sr

Until recently, $^{80}$Sr was thought to possess only positive-parity states, in contrast to many other neighboring nuclei which are known to have negative-parity states. Now there is indirect experimental evidence for negative-parity states, but the parities have not been measured directly. The goal of this study was to finally resolve this long-standing mystery by measuring conclusively the parities of as many excited states in $^{80}$Sr as possible. $^{80}$Sr nuclei were produced at Florida State University following the $^{54}$Fe($^{28}$Si, 2$p$) and the $^{54}$Fe($^{28}$Si, $\alpha$2$p$) reactions at 90 and 110 MeV, respectively. Following the reactions, high-spin states in $^{80}$Sr were populated and data were collected on the resulting cascades of emitted $\gamma$ rays using an array of 10 Ge detectors. The linear polarizations of 31 $\gamma$ rays were measured and many times allowed for the determination of the parity of the parent state that released the $\gamma$ ray. The results have conclusively verified negative parity for one sequence of states, and positive parity for the yrast states.   

A Study on Position Resolution within Resistive Plate Chambers

The PHENIX experiment which operates at Brookhaven National Laboratory using the Relativistic Heavy Ion Collider, explores the quark-gluon structure within the proton. An upgrade is currently underway to integrate Resistive Plate Chambers (RPC) into the detector setup to act as a trigger for high transverse momentum muons that are often produced from the decay of W-bosons. To understand the performance of the RPCs before their production, a cosmic ray test stand has been assembled at the University of Illinois in Urbana-Champaign to test small scale RPCs. This test stand allows for the measurement of signal strength, position resolution, timing resolution, and two-dimensional efficiencies of the avalanches formed within RPCs. Utilizing the position resolution capabilities of this test stand a variety of readout strip configurations were tested. The results of this study including the position resolution and cluster size of the avalanches produced will be presented.   

Continuum Hartree-Fock based Random Phase Approximation Description of the Isovector Giant Dipole Resonance for $^{28}$O,$^{ 60}$Ca and $^{80}$Zr

Calculations of the nuclear response function for the Isovector Giant Dipole Resonance (IVGDR) have been carried out in the past using the discretized Hartree-Fock Random Phase Approximation (HF-RPA). In many cases they contained violations of self-consistency and a large smearing parameter. To avoid any sources of error we carried out a self-consistent HF-Continuum RPA to determine the IVGDR response function in $^{28}$O, $^{60}$Ca and $^{80}$Zr nuclei. We have also examined the free p-h response in the continuum. The main goal of our research was to determine if the low-lying peaks in the response function were due to resonance or particle threshold effects. We have shown that in some cases the enhancements in the response function at low energies are due to threshold effects. We emphasize that in a discretized HF-RPA these peaks are due to threshold effects and not low-lying resonances.   

The Development of Algorithms For Neutron-Based Threat Determinations

As pulsed fast neutrons bombard a target object, the resultant nuclear reactions allow for elemental analysis by measuring gamma ray energies and intensities specific to each isotope. Our group primarily utilizes this technique to examine the elemental densities of carbon, nitrogen, oxygen and hydrogen to discern threats between inert materials and high explosives. Using Poisson probability distributions to simulate data from the neutron interrogation method, we have developed threat algorithms which couple the nuclear cross-sections of these elements with elemental densities to segregate materials. We will discuss these algorithms and present Receiver Operating Characteristic (ROC) curves for each determination process to express the likelihood of each material being correctly identified.   

Imaging Energetic Nuclear Particles

This research project looks at two different kinds of silicon detectors used for imaging energetic nuclear particles. More specifically, we made a comparison of the performance of the 16 resistive strip silicon detector to that of the four corner readout position sensitive silicon detector designed for use in measuring heavy ions in space-based telescopes. We compared the two detector types in their use as target detectors at the end of the Momentum Achromat Recoil Separator (MARS) beam line. The target detectors were used in fine tuning the vertical and horizontal foci of radioactive nuclear beams of $^{46}$V and $^{18}$Ne. We have determined the position resolution capabilities and the response in terms of position linearity of the four corner detector by designing a mask with various hole spacings which was placed in front of the detector. We tested the detector when exposed to an alpha source as well as a radioactive nuclear beam using a variety of shaping times of the amplifier. In the future a smaller four corner readout detector will be used to tune beams at the end of MARS, which have a typical size of about 4mm x 4mm (FWHM). The smaller detector will leave more room in the chamber at the end of the MARS beam line for other equipment.   

Segment Energy Calibrations for Segmented Germanium Detectors

In the Segmented Germanium Array at the National Superconducting Cyclotron Laboratory, Germanium detectors are electronically segmented into 32 sections and a central contact. Segment calibrations for this device face several obstacles, including inter-segment coupling for events in which the total energy is shared by more than one segment and cross talk between the electronics that record the events. While often these cases are corrected in methods that do not separate events in multiple segments, this can reduce the available data. In response, a computerized method for calibrating segments has been developed. An offline program matches spectra with a fourth order polynomial fit, correcting for the effects of the nonlinear relation between energy and channel caused by cross-talk. In addition, the program creates parameters for situations resulting from inter-segment coupling. For events in which a $\gamma$-ray is recorded in one segment, parameters for all 32 segments are produced in the calibration. For those in which two segments record the same event, 32x31/2 parameters are produced. This procedure can lead to a 70\% improvement in statistics.   

Combating Nuisance Alarms Caused by the Ship Effect in 3He Based Neutron Detection Radiation Portal Monitors

Ship effect neutrons can present unique challenges in ongoing efforts to interdict illicit nuclear trafficking at border crossings. 3He neutron proportional counters can generate false positives due to these neutron spikes, leading to cumbersome secondary radiation scans. This work explores methods to mitigate these nuisance alarms through a better understanding of how this effect is manifested in different materials, the role of a target's neutron density, and data analysis techniques to account for its effects. We used a mobile RPM equipped with 3He tubes to detect the neutron flux from several commercial products containing NORM. While neutrons from illicit nuclear sources are Poisson in their frequency distribution, those from background are not. Ship effect neutrons deviated from a Poisson distribution when binned over 0.1 sec time intervals, however when averaged over 2.0 sec intervals the ship effect neutron spikes were washed out, recovering a Poisson distribution. These findings provide underlying knowledge regarding ship effect neutrons emanating from some common bulk materials, and suggest a data analysis algorithm to distinguish between innocent ship effect neutrons and neutron-emitting illegal sources.   

Search for New Physics in Long-Lived Particles that Decay to Photons

We look for beyond Standard Model physics using a Gauge Mediated Supersymmetry Model, which predicts events where a neutralino decays to a photon and a graviton. We use the new EMTiming system at the Collider detector at Fermilab to measure the delay in the photon arrival time from the Standard Model predicted photon. Depending on the exclusion region of the neutralino mass, the gravitino can be a warm dark matter candidate. We extend the GMSB by a few GeV/c$^{2}$ getting closer to a cosmology region where the gravitino mass is such that it is possible for it to have been thermally produced in the early universe. If the gravitinos are too light ($<$1 keV/c$^{2})$ then they can destroy the nuclei produced during the Big Bang Nucleosynthesis and can lead to a cosmic microwave background that is different from observations. If they are heavy ($>$1 keV/c$^{2})$ then, while they are a warm dark matter candidate, their density can cause the universe to overclose if there is no dilution mechanism.   

Analysis of Gamma-Ray Spectroscopy Using the LabVIEW Programming Environment

The LabVIEW programming language is very popular for creating data acquisition and analysis software. However analysis systems which require a heavy amount of data manipulation and comparison algorithms, such as for spectral analysis, are typically approached with languages such as C. Our goal is to create an analysis system for $\gamma $-ray spectroscopy using the LabVIEW programming language. This system will accept data in the form of delimited text and plot the spectra. An algorithm will be implemented to find peaks within the data and identify $\gamma $-rays in the spectra by comparing the measured $\gamma $-ray intensities with tables containing known $\gamma $-ray intensities. By approaching this problem using LabVIEW, which would more typically be used for the acquisition process, we hope to be able to create a more fully-functional and robust software approach to $\gamma $-ray spectroscopy in the future.   

Characterization of the CDMS Ionization Readout

Current cosmological models predict that a large portion of the total mass of the universe, about eighty percent, consists of putative dark matter. Theory predicts this dark matter may be in the form of particles constantly passing through the Earth. A class of these particles may interact with ordinary matter, earning the name weakly-interacting massive particles (WIMPs). The Cryogenic Dark Matter Search (CDMS) aims to directly detect the existence of WIMPs. CDMS has designed ZIP (Z-dependent Ionization \& Phonon) detectors which measure phonon production and ionization of an interaction, making it possible to determine the interacting particle. The low-energy threshold of the ZIP detectors is determined by the signal-to-noise ratio of the ionization readout. A characterization of the signal-to-noise ratio of the ionization readout, along with possible modifications for improved sensitivity will be presented.   

Astrophysical factor for the CNO cycle radiative capture reaction$^{15}\mbox{N}(p,\gamma )^{16}\mbox{O}$

The reaction ${ }^{15}\mbox{N}(p,\gamma ){ }^{16}\mbox{O}$ leaks from CN cycle and determines the oxygen isotopes generated in CNO tri-cycle. Direct measurements of the astrophysical S(E) factor for this reaction were reported [1]. The analysis [1] assumes that the reaction is dominated by resonances at $E_{cm} =312\,\,\mbox{and}\,\,964\,\,$keV, and direct capture to the ground state of ${ }^{16}\mbox{O}.$ The ANCs for bound states of ${ }^{16}\mbox{O}$ have been measured in reaction ${ }^{15}\mbox{N}({ }^3He,d){ }^{16}\mbox{O}$ [2]. Using these ANCs, the astrophysical factor for ${ }^{15}\mbox{N}(p,\gamma ){ }^{16}\mbox{O}$ has been calculated by the R-matrix approach. The proton and $\alpha $ widths of two resonances were determined from the fit to the direct data for ${ }^{15}\mbox{N}(p,\alpha ){ }^{12}\mbox{C}$ [3] and used to calculate the S(E) factor for${ }^{15}\mbox{N}(p,\gamma ){ }^{16}\mbox{O}$. Radiative were varied within experimental uncertainty to fit to the direct data for ${ }^{15}\mbox{N}(p,\gamma ){ }^{16}\mbox{O}$. The calculated S(E) factor is $S(0)=38\,$keVb if we fit the S(E) factor at the resonance peaks; this is significantly smaller than the value $S(0)=64\pm 6$ keVb reported in [1]. Hence, one reaction ${ }^{15}\mbox{N}(p,\gamma ){ }^{16}\mbox{O}$ occurs for almost 1500 CN cycles, rather than 880 cycles as estimated in [1]. The problem with fitting the data from [1] at resonance peaks and small energies necessitates re-measurement at lower energies of this reaction. [1] Rolfs, C., and Rodney, W.S., \textit{Nucl. Phys. }A235 (1974) 450. [2] A. M. Mukhamedzhanov, P. Bem, V. Burjan et al., Phys. Rev. C (will be submitted). [3] A. Redder et al., Z. Phys. A305, 325 (1982).   

Detector Optimization for Fermilab E906

The goal of Fermilab experiment E906 is to extend the measurements made by its predecessor, E866/NuSea, whose result contradicted flavor symmetry in the nucleonic sea. E866/NuSea measured the Drell-Yan (D-Y) cross-sections for fixed target proton-proton and proton-deuterium collisions at the beam momentum of 800 GeV/c, and extracted the light anti-quark distribution ratio of anti-down ($\bar{d}$) to anti-up ($\bar{u}$) quarks inside the nucleonic sea for various momentum fractions (Bjorken-x) up to 0.345. By using the Fermilab Main Injector at $p=120 GeV/c$, E906 will increase the number of D-Y events by approximately a factor of 50. This will result in significantly smaller errors in the region $x>0.2$, where statistics for E866/NuSea were limited. We have used two Monte Carlo programs to optimize the E906 detector for acceptance, multiple scattering, and background rates. One is based on GEANT4, and the other is a fast Monte Carlo written specifically for D-Y events. The results and methods for each of these will be presented to demonstrate balancing an all-inclusive type model, which can be slow (GEANT), versus a faster M.C. approach that includes only the minimal details of the interactions.   

Tests of spurious levels for neutron or proton resonance data

Nuclear level densities are important in a variety of applications. One method of determining these densities near separation energies is the measurement of resonances with either neutron or proton beams. However, experimental limitations often lead to levels being missed or levels being mistakenly included. Resonance levels are believed to be described by random matrix theory (RMT); therefore, the effects on the nearest-neighbor spacing distributions (NNSD) of both missing and spurious levels are known. We have studied via Monte Carlo and maximum-likelihood methods how well the analysis of spacing distributions can provide estimates of the fraction of spurious or missing levels in a set of energy levels. Results will be presented.   

Quark recombination in high energy collisions for different energies

We examine hadron production in high energy collisions performed at the Relativistic Heavy Ion Collider (RHIC) with different energies, impact parameters, and nuclei. The mechanisms of recombination as well as fragmentation are thus examined across a wider scale of collisions, allowing for extrapolation of their relative contributions to hadron production. The radial flow and volume were seen to be sensitive to changes in energy, impact parameter, and the colliding nuclei.   

A search for the decay $\eta' \rightarrow \pi^+ \pi^- \pi^0$ in CLAS data

The primary decay modes for the $\eta'$ are $\pi^+ \pi^- \eta$ and $\rho \gamma$, with respective branching ratios of 44.5\% and 29.4\%. The g11 dataset from Jefferson Lab and the CLAS detector contains about 500,000 events of the type $\gamma p \rightarrow p \eta'$ where the $\eta'$ is reconstructed from the former decay mode. Access to relatively large statistics motivated the search for previously unseen decay modes. With the excellent charged track identification that CLAS possess, a search was made for the decay $\eta' \rightarrow \pi^+ \pi^- \pi^0$. This decay is listed in the PDG with only an upper limit of a 5\% branching ratio at CL=90\%. We search for this decay by measuring all charged tracks in the final state and reconstructing the neutral pion. We see no evidence for this decay and present the results of a careful study which shows that $\eta'$ peaks in this channel are more likely bleed-through from misidentified $\pi^+ \pi^- \gamma$ decays.   

Alpha Particle Scintillation Analysis in High Pressure Argon Using Photomultiplier Tubes

We may very likely discover dark matter by studying what it is not rather than what it is. By better understanding how ordinary matter interacts with other ordinary matter, dark matter interactions should stand out. That's why physicists such as my mentor, Dr. James White, are studying the affects of scintillation events due to ionizing high pressure noble gasses with gamma rays, alpha particles, neutrons, and electrons. My project has been using photomultiplier tubes and a high pressure pure argon gas chamber to study scintillation events. We have focused mainly on alpha particles (as well as gamma rays from decaying Cobalt-57 and neutrons from a 4-MeV proton accelerator). The resulting shape of the events, the ratios of secondary to primary scintillation, and the ratios of triplet state to singlet state decay energies helps catalog ordinary matter interactions.   

Transmission Profiles of a Mini-Orange Spectrometer for Conversion-Electron Spectroscopy

A Mini-Orange Spectrometer (MOS) consists of an orange-type array of 3, 4, or 6 permanent magnets that focus electrons onto a cooled Si-Li detector. At the center of the array is a lead plug for shielding gamma rays and delta electrons. Since electron transmission of an MOS is highly energy dependent - electrons with too much or too little energy are not bent into the detector - measuring transmission as a function of electron energy is an important callibration task, allowing the MOS to make absolute intensity measurements for conversion electron lines. We report a method for calculating the absolute transmission for an MOS using standard calibration sources, as well as discuss the relevance of conversion electron spectroscopy to the study of nuclear structure.   

Simulation of the Focal Plane Detection Systems for the study of the 12C(a,g)16O Reaction with St. George Recoil Separator

The 12C(a,g)16O reaction is one of the most important reactions in nuclear astrophysics. The lowest energy we have reached is limited by the background in the detectors. To reduce the background, the St. George recoil separator is designed to study the radiative capture reactions with inverse kinematics. One key instrument of the recoil separator is the detection system at the focal plane used to identify the 16O reaction products from the 12C leakage through the recoil separator. Several focal plane detection systems were simulated with SRIM-2006 to determine the optimal conditions for particle identification. These simulations include a time of flight (TOF) and gas ionization chamber (GIC) configuration, as well as a double TOF configuration. Based on the simulation, the best detection solutions are recommended. Non-uniformities in the entrance window of the GIC and in the energy degrader of the double TOF system were also explored, and affect particle identification greatly, suggesting the necessity of tracking components to correct for large scale non-uniformities.   

Search for the states in $^{8}$B via $^{7}$Be + d

The spectroscopy of the light drip-line nuclei provides an important test of nuclear models (e.g., no-core shell models and cluster models) at the extremes of isospin. Few excited states have been observed [1] in the $^{8}$B nucleus, including the mirror of states in $^{8}$Li (e.g., the 4+ $^{8}$Li state at 6.53 MeV) that may have exotic configurations. We have searched for states in $^{8}$B by bombarding a CD$_{2}$ target with a $^{7}$Be radioactive ion beam at ORNL's Holifield Radioactive Ion Beam Facility. The light charged particles (p, $^{3}$He, and $^{4}$He) emitted from the decay of $^{8}$B were detected in triple coincidence to reconstruct possible excited states in $^{8}$B. The present focus is on the analysis of the triple coincidence data. Preliminary results and implications for the $^{8}$B level structure will be reported. This work supported in part by the U.S. Department of Energy and the National Science Foundation. [1] D. R. Tilley \textit{et al.}, Nucl. Phys. A 745, 155 (2004)   

Dilepton Spectra from Open-Charm Decays in Heavy-Ion Collisions

In heavy-ion collisions at ultra-relativistic energies, light quarks are quickly thermalized and lose their originally imprinted information while heavy quarks, such as charm quarks, take longer to thermalize. Thus, by studying charm quark spectra, we will be able to better understand the interactions in the quark-gluon plasma. In this project we have focused on di-electron invariant-mass spectra from correlated charm decays. We first generated a realistic distribution for the transverse-momentum (pt) spectra of charm and anti-charm quarks. Then we generated the histogram of invariant-mass distributions of electrons and positrons which result from the decay of charm-anti-charm pairs. We tested the sensitivity of the dilepton spectra to slopes in the charm pt spectrum and to different angular distributions of charm pairs. The goal is to analyze how the interactions of single charm quarks reflect themselves in the di-electron invariant-mass spectrum.   

Fiducial Volumes for Photons Detected in the Electromagnetic Calorimeters of the CLAS Detector at Jefferson Lab

Fiducial volumes have been determined for photons detected in the electromagnetic calorimeters of the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. This work is part of a systematic study of neutral meson photoproduction from the proton and light nuclear targets over an incident photon energy range of 0.5 - 1.5 GeV to investigate nuclear medium modifications of nucleon resonances and the meson-nucleon interaction. In this analysis the neutral mesons are reconstructed from their two-photon decay. The fiducial volumes define regions of the calorimeters with full photon detection efficiency. The volumes were determined by examining the photon hit distributions along the different scintillator planes in the sampling calorimeters. The procedure will be described and the results will be presented.   

Statistical Analysis of Proton and Neutron Resonance Data

Random matrix theory (RMT) is thought to describe statistical properties of neutron and proton resonance data. Very strong evidence for this conclusion comes from a 1982 analysis by Haq \emph{et al.}\footnote{R. U. Haq \emph{et al.}, Phys. Rev. Lett. \textbf{48}, 1086 (1982).} of the Nuclear Data Ensemble (NDE), a collection of resonance levels from 32 different nuclides. Because newer data are available for many of the nuclides in the NDE, an updated data set is appropriate. We have examined current resonance data for the nuclides in the original NDE as well as for other even-even targets. N(E) ``staircase'' plots and comparisons of reduced widths with the Porter-Thomas distribution are utilized as tests of data quality. Of the NDE's original 35 sequences, we have retained 11 sequences with new data and 10 sequences with the original data. We have also included 5 new sequences from nuclides not included in the original NDE. Several different statistical tests have been performed. Thus far, the data have shown good agreement with expected behavior.   

The production of light $p$-process nuclei in the outflows from gamma-ray burst accretion disks

Elements created through $p$-process nucleosynthesis are some of the rarest in the universe. Here we examined the outflows from gamma ray burst accretion disks as a possible site for the production of some light $p$-process nuclei. We began by using a calculated model of a black hole accretion disk with a mass accretion rate of one solar mass per second, then using a parameterized outflow model we calculated isotropic abundances for various outflow trajectories. We then examined overproduction values for several light $p$-process nuclei. We found two regions in our parameter space which showed significant overproduction of some of these nuclei. The electron fraction in the outflow material was between 0.4 and 0.5 in the first region of overproduction and over 0.6 in the second region. In the latter, we find that production is aided by neutrino reactions on free nucleons. Our study indicates that outflows from gamma ray burst accretion disks are a promising site for the synthesis of some light $p$-process nuclei, and that neutrino interactions can play an important role in this nucleosynthesis.   

Studies of Polarization Rotation in a Storage Ring

A published proposal for an electric dipole moment search on the deuteron [PRL \textbf{96}, 214802] requires that the deuteron beam be polarized horizontally in the plane of a storage ring. The beam is vertically polarized at injection and, through the action of an RF solenoid operating for a fixed time, this polarization must be precessed into the horizontal plane. Treating the precession classically, we investigated ramping the solenoid frequency until it reached the spin tune resonance at $\nu _{s} = G\gamma f_{cyc}$. As a limiting case, we also investigated operating at $\nu _{s}$ for a fixed time. The parameters for these simulations were taken from recent studies [PRSTAB \textbf{8}, 099002] at COSY where this scheme will be tested. We have demonstrated that our model can reproduce the results of these studies of deuteron spin flip, including the effects of momentum spread. We show that beam bunching is required to maintain the polarization. Some sensitivity to momentum spread remains at second order, an effect that also contributes to the polarization decoherence time once the polarization is horizontal.   

Neutron Background Evaluation for Dark Matter Detectors at DUSEL

One of the fundamental mysteries in the 21st century is the nature of dark matter in the universe. A study by the National Academies on the Physics of the Universe identifies this phenomenon as one of the most important experimental pursuits of modern science. A compelling explanation requires physics beyond the Standard Model in the form of Weakly Interacting Massive Particles (WIMPs) that could be detected directly as they recoil from massive and ultra-pure detector targets operating deep beneath the Earth's surface. The Homestake Mine in western South Dakota has been confirmed as the site for the Deep Underground Science and Engineering Laboratory (DUSEL), and the US high energy and nuclear physics communities have indicated a strong intention to play a leading role in future neutrino and dark matter experiments as part of DUSEL programs. The institutions in South Dakota intend to play a key role in the worldwide effort to identify cosmological dark matter at Homestake. The purpose of this project is to identify the neutron-induced backgrounds for the liquid argon detector proposed for the dark matter search.   

Diamond Detector for Compton Polarimetry

The $Q_{weak}$ experiment, at Thomas Jefferson National Accelerator Facility, will make a precision test of the Standard Model prediction of the weak mixing angle, sin$^2\theta_W$. The weak charge of the proton will be determined through parity violating electron-proton scattering and sin$^2\theta_W$ will be extracted from this measurement. Compton polarimetry will be used to measure the longitudinal polarization of the incident electron beam to 1\%. In Compton polarimetry, the polarization is extracted from the Compton scattering asymmetry between laser light and electrons polarized parallel and anti-parallel. The asymmetry is measured by detecting the Compton scattered electrons using a bulk semiconductor detector, fabricated from synthetic diamond. Initial prototyping of the diamond detector was successfully carried out and results will be reported. Data acquisition electronics were developed. Additionally, a GEANT simulation was used to model the polarimeter and to perform design studies related to the electron detector.   

Development and Testing of a Novel Lanthanum Bromide Scintillation Detector for SPECT Imaging

A single piece of LaBr$_{3}$ has been coupled ( by Bicron-St Gobain Inc.) to four special position sensitive phototubes (PSPMTs; Hamamatsu, Inc.) to create a novel detector for biological imaging with high sensitivity, very good energy resolution and high spatial resolution. The LaBr$_{3 }$scintillator is coupled to four Hamamatsu H9500 PSPMTs and the resulting detector can be used with parallel or pinhole collimation. To reduce the number of active channels, novel readout circuitry has been implemented. In addition, we have applied special techniques to the achievement of spatial uniformity across the 100 mm$^{2 }$face of the detector. This technique is of special importance at the interfaces of the four square PSPMTs where the continuous scintillator must act to spread the light between the two photosensitive devices due to the reduced sensitivity in these regions. These techniques and results obtained will be described and discussed.   

Optimization of a Light Collection System for use in the Neutron Lifetime Project

The Ultracold Neutron (UCN) Lifetime Project is an ongoing experiment with the objective of improving the average measurement of the neutron beta-decay lifetime. A more accurate measurement may increase our understanding of the electroweak interaction and improve astrophysical/cosmological theories on Big Bang nucleosynthesis. The current apparatus uses 0.89 nm cold neutrons to produce UCN through inelastic collisions with superfluid 4He in the superthermal process. The lifetime of the UCN is measured by detection of scintillation light from superfluid 4He created by electrons produced in neutron decay. Competing criteria of high detection efficiency outside of the apparatus and minimum heating of the experimental cell has led to the design of an acrylic light collection system. Initial designs were based on previous generations of the apparatus. ANSYS was used to optimize the cooling system for the light guide by checking simulated end conditions based on width of contact area, number of contact points, and location on the guide itself. SolidWorks and AutoCAD were used for design. The current system is in the production process.   

Quality Analysis and Control Procedures for the PHENIX RPC Forward Trigger Upgrade

The PHENIX detector is located at Brookhaven National Laboratory on the Relativistic Heavy Ion Collider (RHIC) ring where it studies both heavy ion and polarized proton-proton collisions. One of the primary goals of the polarized proton program is to improve our understanding of the proton's spin structure. A level 1 trigger upgrade is currently being constructed for PHENIX. This will involve the installation of Resistive Plate Chambers (RPCs). These new chambers will improve our ability to trigger on high transverse single muons that are produced in the decay of W bosons. Before these new chambers can be installed they must pass a series of quality control tests. Simple but effective tests will be preformed on internal components of the RPC such as the gas gaps before individual RPC modules are assembled. These tests will yield a pass or fail result for each gas gap. All gaps that pass these tests can then be used in the construction of the RPC modules. Additional tests will be preformed on each assembled RPC module. A list of tests, why they are important, and how they are performed, will be presented.   

DUSEL Ultra-Low Background Counting Facility

The Homestake Mine in western South Dakota has been confirmed by the National Science Foundation (NSF) as the site for a Deep Underground Science and Engineering Laboratory (DUSEL). Many of the physics, geosciences, and microbiology experiments in the facility will be funded by DOE and NSF, and will benefit the missions of these agencies. In support of these programs, physics faculty in South Dakota and scientists at Lawrence Berkeley National Laboratory have been working together to establish a multidisciplinary research cluster to provide baseline characterization for physics and geosciences/geomicrobiology experiments at the Homestake Mine through an Ultra-Low Background Counting Facility (ULBCoF). The proposed project utilizes two low-background germanium detectors with massive shielding underground to carefully analyze materials for low background experiments. Low background experiments such as double-beta decay, solar neutrino, geoneutrino, and dark matter must control the purity of all the materials used in the construction of a detector. Measuring such low counting rates is a very challenging task that will be best accomplished by primarily using high purity germanium (HPGe) detectors.   

Controls Interfaces for Two ALICE Subsystems

Software for the control of a laser alignment system for the Inner Tacking System (ITS) and for the Electromagnetic Calorimeter (EMC) was developed for the ALICE (A Large Ion Collider Experiment) at CERN. The interfaces for both subsystems use the CERN-standard hardware controls system PVSS (Prozessvisualisierungs- und Steuerungs-System). Software for the ITS has been created to measure the relative alignment of the ITS with the Time Projection Chamber (TPC) so to ensure accurate particle tracking. The ITS alignment system locates laser images in four cameras. The EMC requires several subsystems to be running in order to operate properly. Software has been created and tested for the detector's high and low voltage systems, and temperature monitoring hardware. The ITS and EMC software specifications and design requirements are presented and their performance is analyzed.   

Position calibration for a low-energy neutron detector.

A low-energy neutron detector array is being developed for use in (p,n) charge-exchange experiments with radioactive beams. The array will consist of 25 plastic-scintillator bars that are capable of detecting neutrons with energies as low as approximately 200 keV. Since the kinematical reconstructing of a (p,n) reaction is performed using the energy and angle information from the neutron, good energy (measured by time-of-flight) and angle resolutions are important. In the initial testing stage, a single scintillator bar is tested using 22 Na and 252 Cf sources. In the presentation, results from these measurements will be discussed, focusing on the angle resolution of the array.   

A Scattering Chamber System to Measure Cross Sections of Multiple Star Configurations in Neutron-Deuteron Breakup at 19 MeV

The kinematics of the neutron-deuteron\textit{ (nd)} breakup reaction enable observables to be studied in a variety of exit-channel configurations that show sensitivity to realistic nucleon-nucleon (NN) potential models and three-nucleon force (3NF) models. Rigorous 3N calculations give very good descriptions of most 3N reaction data. However, there are still some serious discrepancies between data and theory. The largest discrepancy observed for \textit{nd} breakup is for the cross section for the space-star configuration. Several experimental groups have obtained results showing this discrepancy but it is important to note that they all used essentially the same experimental setup and so their experimental results are subject to the same systematic errors. We will discuss a new scattering chamber system that we have developed to measure simultaneously the cross sections of multiple orientations of the star configuration in \textit{nd} breakup at 19.0 MeV utilizing an experimental technique that is significantly different from the one used in previous breakup experiments.   

MINERvA Experiment

The MINERvA experiment at FNAL will make a high statistics study of neutrino scattering on nuclei. One objective is to study nuclear effects on the axial form factor using quasi- elastic scattering from carbon, iron, and lead. We will present an estimate of the sensitivity of the detector to changes in the form factor.   

Increased Precision in Gamow Window Calculations for Thermonuclear Reaction Rates

The simulations of many astrophysical events require the input of thermonuclear reaction rates. These rate calculations involve a numerical integration over the Gamow window for each reaction. Standard codes to calculate rates, such as the tools at nucastrodata.org, utilize a Gaussian approximation\footnote{See, e.g., C. E. Rolfs and W. S. Rodney, ``Cauldrons in the Cosmos,'' The University of Chicago Press, Chicago (1988), p. 158.} to estimate the relative energy range (Gamow window) over which the calculation is performed numerically. This analytic method fails for low Z particles such as d($d,p$)t and d($d,n$)$^3$He reactions at low temperatures, which are important for Big Bang Nucleosynthesis (BBN). A new FORTRAN code was written and tested that numerically determines the lower energy limit whose contribution to the integration over the Gamow Window is less than 1.0\% at a given temperature. The code also determines the Gamow peak energy numerically, instead of using the formula for a constant S-factor. These developments will extend the rate calculation capabilities at nucastrodata.org to include BBN and enhance upcoming features at bigbangonline.org. This research is supported by the U. S. Department of Energy.   

Search for Upward Cosmic Rays

The Modular Neutron Array, or MoNA, is a detector located at the NSCL that consists of 144 individual scintillator modules. MoNA is designed to detect fast neutrons, and because plastic scintillators were chosen for the detector, MoNA is also capable of detecting cosmic ray muons. Data taken from the muon detection is typically used for calibration purposes, however, at the same time the angular distribution of cosmic ray muons can be measured. The angular distribution of cosmic rays muons is known to be proportional to cos$^{2}(\theta )$, measured from the zenith. However, this only applies to angles less than 90\r{ }. Events at larger angles have been observed at large underground detectors with intensities reduced by several orders of magnitudes. These events are attributed to cosmic ray neutrinos and show an almost flat angular distribution. MoNA is not sensitive to these events. However, we did observe events at angles larger than 90\r{ }. The intensity decreases with increasing angles. The origin of these events is not understood, however, before any conclusions can be drawn, all possible sources of background or random coincidences have to be excluded. Work supported by NSF grants (PHY-0606007. PHY-0243709).   

$^{238}$U Fission Ion Chamber for Neutron Dosimetry at the 88-Inch Cyclotron

Efficiency measurements have been conducted for a commercial $^{238}$U fission ion chamber, to be used for neutron dosimetry at the 88-Inch Cyclotron at LBNL. Fast, quasi-monoenergetic neutrons in the energy range of 5 to 30 MeV are under development at the facility through deuteron break-up, for radiation effects testing and cross-section measurements for a variety of applications. Through comparisons with absolute fluxes obtained using activation foils, and energy spectra obtained using the time-of-flight method, efficiency for both monoenergetic and white spectrum neutrons can be calculated.   

Time Stability in Detectors for a 1 ppm Measurement of the Positive Muon Lifetime

The MuLan experiment aims to obtain a 1 ppm measurement of the positive muon lifetime. In a 22 $\mu$s measurement period for the muon lifetime there are considerably more muon decays at the start of the time and less near the end. We will determine if this bombardment of positrons will create a time delay within the detectors. A laser pulse is sent to 24 of the 340 detectors used to make the positive muon lifetime fit. The same pulse is also sent to a reference detector that does not go into the lifetime fit. The laser pulses are used to measure the time difference between the reference detector and the 24 detectors used to make the lifetime fit. If the muon bombardment does make a considerable difference, then graphing the mean time difference for a specific detector vs the time in the measurement period will show a slope. For a 1 ppm measurement, we need to make sure the time difference at the beginning of the period is within 2.2 $\times$ 10$^{-13}$ s from the end of the period.   

Raman Spectroscopy as a way to determine Ortho to Para Ratio of Deuterium

A superthermal ultracold ($<$350 neV) neutron source using a solid Deuterium (D$_{2}$) crystal is being developed at the NC State University PULSTAR nuclear reactor. Ultracold neutron production in the solid D$_{2}$ crystal requires that the D$_{2} $ be in the ortho (total nuclear spin of 0) rotational state, as D$_{2}$ in the para (spin 1) rotational state interacts with ultracold neutrons by transferring energy to the neutrons. A novel method to determine the ortho/para-D$_{2}$ ratio is to use Raman spectroscopy to determine the fraction of rotational states in the D$_{2}$. This project focuses on the design, construction, and ultimate use of a double-grating Raman spectrometer to determine the ratio of ortho-D$_{2}$ to para-D$_ {2}$. This system is critical to the optimization of the para-to- ortho-D$_{2}$ converter which produces D$_{2}$ for the ultracold neutron source. I will present details on the Raman spectrometer's construction and performance, as well as Raman spectra obtained for air and regular D$_{2}$ (with 30\% para-D$_ {2}$ content).   

Photoproduction of eta mesons off protons at CB-ELSA

QCD-inspired models predict more states in the hadron mass spectrum than have been seen experimentally. Models show that some of these states should be observed in photoproduction experiments, thus providing a sensitive tool to study hadron properties. Baryon resonances have broad, overlapping widths. Photoproduction of $\eta$ mesons serves as an isospin filter; the $\eta$ meson has isospin $I=0$ and for this reason, isospin conservation guarantees that the N$\eta$ final state can only be reached via formation of N$^\ast$ resonances. Contributions from $\Delta^\ast$ states with $I=3/2$ are excluded. We used the Crystal-Barrel Detector (CsI(Tl) calorimeter) at ELSA to determine the cross-section of the reaction $\gamma p\to\eta p$ studying the $\eta$ in its two neutral decay modes ($\eta \to 3\pi^{0} \to 6\gamma$ and $\eta \rightarrow 2\gamma$) for photon incoming energies in the range of $E_{\gamma} = 850-3000$ MeV. In this experiment, the Two-Armed Photon Spectrometer (TAPS) was placed in the forward direction. This BaF$_2$ calorimeter serves as a fast trigger and increases the overall angular coverage to essentially the full $4\pi$ solid angle. We present differential cross sections for $\eta$ photoproduction off the proton for ($-1 < {\rm cos}\,\theta^{\rm cms}_\eta < 1$). Approximately 600,000 events have been identified. Preliminary results of a partial wave analysis are discussed.   

Bakelite Surface Resistivity Measurements for Muon Trigger RPCs in PHENIX

The PHENIX experiment, at Brookhaven National Lab, studies polarized proton-proton collisions in order to explore the origin of the proton spin. A forward trigger upgrade for the PHENIX detector will provide a first level trigger for high $p_T$ single muons produced from the decay of $W$-bosons. The measurement of spin sorted yields of $W$s makes it possible to measure the spin distributions for quarks and anti-quarks in the proton. The muon trigger upgrade will be based on fast Resistive Plate Chambers (RPCs). The RPC gas gaps will be manufactured from bakelite plates. High rate capabilities are a key requirement for the PHENIX muon trigger RPCs and special attention has been given to the bulk and surface resistivity of the bakelite. Due to the manufacturing process for bakelite, the resistivity of the bakelite can vary significantly within a sheet but also between sheets. Large variations in the surface resistivity have a negative effect on rate capabilities and the detector efficiency. I will present a survey of bakelite surface resistivities for a sample of 17 large bakelite sheets to be used for the PHENIX trigger RPC prototypes.   

Scintillation Studies of the Mouse Mammary Tumor Virus with $^{125}$I

We have applied the techniques of scintillation imaging to studies of the mouse mammary tumor virus (MMTV). In these studies, Sodium Iodide Symporter (NIS) transfers the radioactive $^{125}$I to the mammary glands of lactating mice and in particular to those mammaries with visible tumors. These studies have principally been carried out using pixellated scintillators coupled to position sensitive photomultiplier tubes (PSPMTs). More recently, we have initiated such studies with a monolithic slab of LaBr$_{3}$ scintillator coupled to an array of PSPMTs. Several techniques of mapping and measuring the development of such tumors have been employed. These will be discussed in detail and preliminary results will be reported.   

Efficiency and Multi-Hit Capability Improvements of MoNA

Located at the National Superconducting Cyclotron Lab at Michigan State University, the Modular Neutron Array (MoNA) consists of 144 detectors 2 meters in length stacked in a nine by sixteen block. MoNA is designed to be used with a sweeper magnet to detect and study rare nuclei at and beyond the neutron dripline that decay by neutron emission. MoNA can also be used to detect high-energy cosmic-ray muons. Recently MoNA has been relocated and reassembled in order to improve the efficiency and the multi-hit capability. When MoNA was relocated, it was separated into four groups of vertical columns instead of one large block. This separation improves the accuracy of identifying two-neutron events from scattered single neutron events. In addition, the new location allows for the columns to be located at different angles increasing the efficiency for larger decay energies. Following the reassembly the array had to be recalibrated in order to calculate timing, energy, and x-position of the neutrons. The relative timing offsets of the individual detectors was performed using cosmic-ray muons. The new setup, with the larger separation of columns between the groups required a new method to determine the offsets between the columns. Cosmic-ray data were taken to record a sufficient number of muons traversing detectors of both of two separated columns. The relative offsets between all columns were then sequentially determined.   

Calibration and Performance of the UConn-Yale-PTB-Weizmann-UCL-TUNL O-TPC

An Optical Readout Time Projection Chamber (O-TPC) will be used in an experiment at the HigS facility at Duke University for studying oxygen formation during stellar helium burning. The calibration of the O-TPC was carried out at the LNS at Avery Point prior to installation at TUNL in August 2007. A variety of pre-amplifers and high voltage power supplies were tested and under stable conditions an energy resolution as good as 3.5 {\%} was found in the charge signal. Charge and light gain curves were obtained using a Gd-148 source and a 75 mm diameter PMT placed at approximately 85 cm. These determined the optimal conditions for operating the O-TPC. Under the optimized conditions a CCD camera was used to capture images of single and double tracks of alpha particles from a Gd-148 source. The 3.18 MeV alpha particles yielded tracks containing only 40-50 photo electrons due to the small lens currently in use.