Bulletin of the American Physical Society
81st Annual Meeting of the APS Southeastern Section
Volume 59, Number 18
Wednesday–Saturday, November 12–15, 2014; Columbia, South Carolina
Session HA: Low Energy Nuclear Physics II |
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Chair: Mark Spraker, University of North Georgia Room: Lexington |
Friday, November 14, 2014 11:00AM - 11:12AM |
HA.00001: Searching for new Flerovium isotopes Invited Speaker: N.T. Brewer Experiments with $^{239,240}$Pu targets and $^{48}$Ca beams began at Dubna in November 2013. These studies, to identify decay chains starting from $^{283-5}$Fl isotopes, are using a new detection system and digital data processing commissioned by the ORNL-UTK team, and implemented at the Dubna Gas Filled Recoil Separator. These experiments are expected to expand our knowledge regarding properties of known and new nuclei located at the gap between the Hot Fusion Island and the Nuclear Mainland. New data may enrich information on the competition between alpha decay and spontaneous fission (SF) in super heavy nuclei. The new system demonstrably provides better validation and correlation of fast decays with implanted recoils, even in sub-microsecond time intervals. The plans for a search for new isotopes with Z=118 will also be shown.\\[4pt] In collaboration with K.P. Rykaczewski, J.B. Roberto, Oak Ridge National Laboratory. R. Grzywacz, ORNL/Univ. of Tennessee, Knoxville; K. Miernik, ORNL/Univ. of Warsaw, Poland; V.K. Utyonkov, Yu. Ts. Oganessian, A.N. Polyakov, Yu S. Tsyganov, A.A. Voinov, F. Sh. Abdullin, S.N. Dimitriev, M.G. Itkis, A.V. Sabelnikov, R.N. Sagaidak, I.V. Shirokovsky, M.V. Shumeyko, V.G. Subbotin, A.M. Sukhov, G.K. Vostokin, JINR Dubna, Russia; J.H. Hamilton, Vanderbilt University; and R.A. Henderson, M.A. Stoyer, Lawrence Livermore National Laboratory. [Preview Abstract] |
Friday, November 14, 2014 11:12AM - 11:24AM |
HA.00002: Measuring neutron recoil polarization in the photoproduction off deuterium Svyatoslav Tkachenko The dependence on the photon energy of the neutron recoil polarization Py' in the inclusive polarized photoproduction off the deuteron is not well-understood. The only comprehensive measurement by Nath et al lines up with both potential and effective field theory models up to a photon energy of about 12 MeV and then abruptly departs, indicating the possibility of a new channel opening. The Py' angular dependence is not known well either, the few existing measurements having large uncertainties. We will measure Py' for a range of photon energies and neutron scattering angles, covering the kinematic region in which the discrepancy between data and theory exists. The measurements will be performed at the High Intensity Gamma Source (HI$\gamma$S) facility located at Duke University. A heavy water target in conjunction with a set of analyzer/scintillator-cell assemblies will provide polarization analysis of the ejected neutrons. The experiment will take place in 2015, with physics results expected in 2015-2016. [Preview Abstract] |
Friday, November 14, 2014 11:24AM - 11:36AM |
HA.00003: Measurement of the Double Polarization Observables $C_x$ and $C_z$ for $\Lambda n$ Final-state Interactions in $\overrightarrow{\gamma} d\rightarrow K^+ \overrightarrow{\Lambda} n$ Tongtong Cao Building a comprehensive picture of the strong interaction is the goal of modern nuclear physics. While considerable progress has been made in the understanding of the nucleon-nucleon (NN) interaction, we are still far from a complete understanding of the hyperon-nucleon (YN) interaction, which plays a key role in hypernuclear matter and neutron stars. Some parameters of the YN potential can be obtained from the NN potential by using SU(3) symmetry. Since the flavor SU(3) is broken, there are free parameters in the YN potential, which cannot be obtained from the NN potential and must be obtained from fits to experimental data. One can access the dynamics of the YN interaction by studying nuclear reactions in which hyperons are produced. In this talk we will present preliminary results of the polarization observables $C_x$ and $C_z$ for final-state interactions in the reaction $\overrightarrow{\gamma} d\rightarrow K^+ \overrightarrow{\Lambda} n$. We use data taken with the CLAS detector at Thomas Jefferson National Accelerator Facility. Our results are the first data ever obtained for $C_x$ and $C_z$ and will provide stringent constraints on the theoretical models of the YN potential. This work is funded in part by the U.S. NSF under grant PHY-125782. [Preview Abstract] |
Friday, November 14, 2014 11:36AM - 11:48AM |
HA.00004: Optimization of EJ-200 Scintillators' Optical Surface Area for the GlueX Start Counter Anthony Llodra, Eric Pooser For the GlueX Start Counter to operate at maximum efficiency a time resolution of \textless 350ps is required to identify the electron beam buckets produced by the Continuous Electron Beam Accelerator Facility at Jefferson Lab. Thirty EJ-200 machined scintillator paddles were utilized for the Start Counter due to its fast decay time of 2 ns, long attenuation length, and high light output. The geometry of these paddles consists of a long straight section, a bend section, and a tapered nose section. Over a period of three months, five prototypes were closely monitored for degradation at Florida International University. Fifty scintillators were machined in June of 2014. However, the initial surface quality did not meet our specifications. After several polishing trials, a polishing procedure was established which resulted in an improvement of the overall surface quality and subsequently a vast improvement in time resolution. The optimization of the scintillators optical surface quality and the physical properties of the scintillator paddles will be discussed. This work was supported in part by DoE contracts DE-FG02-99ER41065 and DE-AC05-06OR23177. [Preview Abstract] |
Friday, November 14, 2014 11:48AM - 12:00PM |
HA.00005: Heavy flavor muons at forward rapidities in $\sqrt{s_{NN}}=200$ GeV p+p, d+A, and A+A collisions Matthew Wysocki The dynamics of heavy flavor production and suppression in $A$+$A$ collisions play an important role in unraveling the properties of the quark-gluon plasma produced at RHIC. The related observables offer direct insight into strongly-coupled nature of the medium. It has also become increasingly apparent that the production and suppression in the absence of a hot medium need to be studied in detail, via comprehensive measurements in $p$+$p$, $p$($d$)+$A$, and $A$+$A$ collisions of varying size and energy at RHIC and the LHC. I will present the latest heavy flavor invariant yields and nuclear modification factors at forward rapidity in $\sqrt{s_{NN}}=200$ GeV $p$+$p$, $d$+Au, and $A$+$A$ collisions recorded at PHENIX and discuss their implications for our current understanding of heavy flavor production. [Preview Abstract] |
Friday, November 14, 2014 12:00PM - 12:12PM |
HA.00006: Nuclear Astrophysics with the Enge Split-pole Spectrograph at TUNL Richard Longland The Enge Split-pole Spectrograph at the Triangle Universities Nuclear Laboratory (TUNL) has a history of performing high resolution particle spectroscopy measurements important for understanding astrophysical reactions. After a 15-year operational hiatus, the spectrograph is now being re-commissioned, making it the only functioning spectrograph of its kind in North America. I will summarize past research of the Enge Split-pole at TUNL and outline its experimental program going into the future. In particular, I will highlight upgrades currently underway to implement an advanced data acquisition and detector system to perform particle-$\gamma$ and particle-particle coincidence measurements. [Preview Abstract] |
Friday, November 14, 2014 12:12PM - 12:24PM |
HA.00007: Self Organizing Maps Evan Askanazi Self Organizing Maps (SOMs) are a type of artificial neural network that has been proven to be particularly useful in solving complex problems physics. The SOM uses an unsupervised learning process to map initial data onto final data and because it allows us to visualize multi dimensional data into two dimensional format. We are attempting to use the SOM to probe phenomenological patterns in Deep Inelastic Scattering (DIS). In DIS there is a cross section in electron hadron scattering that is dependent on the momentum fraction x of the partons in the hadron and the momentum transfer of the virtual photon exchanged. There is a part which is comprised of Structure Functions which in turn are comprised of the Parton Distribution Functions (PDFs). We aim to use the SOM to take theoretical models of these PDFs and fit it to the previous, known data. We aim to make the resulting Structure Functions fit the data results as closely as possible and make the comprising PDFs fit the PDFs determined by other collaborations as closely as possible as well. The Self Organizing Process will also be used to probe the behavior of the Parton Distribution Functions, in particular at large x values, in order to observe how they congregate. [Preview Abstract] |
(Author Not Attending)
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HA.00008: Single Event Effects from Ions Produced in Nuclear Reactions of Transistors with Cosmic Rays William Atkinson Single Event Effects (SEEs), disruptions in a microelectronic device caused by the passage of an energetic particle through the sensitive region of the device, are an increasing problem with advances in technologies. Two trends are responsible for the increased number of SEEs over the last decade. First, with the reduction of the operating voltages, devices have are susceptible to smaller amounts of radiations. Secondly, the data densities (bits per device) increased dramatically to meet the demand for more memory and faster processing time. This paper presents .models for generating typical near earth radiation environments in space as well as in the atmosphere, a model for transporting these radiations across the various materials of the device, and programs to compute the SEE rate of the device from data generated by the transport model using detailed structures available for the devices modeled. The results show that with the continued trends, nano size circuits become especially vulnerable to direct and indirect ionization (ions produced as a result of nuclear reactions with the circuit materials. [Preview Abstract] |
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