Bulletin of the American Physical Society
84th Annual Meeting of the APS Southeastern Section
Volume 62, Number 13
Thursday–Saturday, November 16–18, 2017; Milledgeville, Georgia
Session B3: Nuclear Physics II |
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Chair: Simon Taylor, Jefferson Lab Room: MSU Building Donohoo Lounge |
Thursday, November 16, 2017 11:00AM - 11:12AM |
B3.00001: Probing Nuclear Interactions and the Quark Gluon Plasma with sPHENIX Anthony Hodges A hot, dense state of matter, known as the Quark Gluon Plasma, is believed to have existed at the infancy of the universe, and it is also created in heavy ion collisions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. To analyze the QGP, a new particle detector, sPHENIX, is currently planned to begin taking data in 2022. The nuclear physics group at Georgia State University is involved in the development and construction of the Hadronic Calorimeter, which measures the energy of hadronic matter produced in the collisions. The sPHENIX hadronic calorimeter itself is composed of individual scintillator tiles embedded with wavelength shifting fibers readout to silicon photomultipliers (SiPM’s). Results from the 2016 prototype test beam of the hadronic calorimeter subsystem demonstrate the hadron energy resolution satisfies the performance requirement for sPHENIX. Additionally, we are working to characterize the performance of the hadronic calorimeter tiles by exposing them to cosmic rays under different conditions. These cosmic ray tests include trigger configuration studies and discriminator threshold characterization using a CAEN DT7502 FEB. Results from these tests will allow us to establish a baseline calibration procedure for data taking with sPHENIX. [Preview Abstract] |
Thursday, November 16, 2017 11:12AM - 11:24AM |
B3.00002: Study of $b\bar{b}$ production in $p+p$ collisions at $\sqrt{s} = 510$ GeV in the PHENIX experiment at RHIC Tristan Haseler Heavy flavor quarks are an important probe of the initial state of the Quark Gluon Plasma formed in heavy-ion collisions. Bottom and charm quarks are produced early in the collision, primarily through hard interactions, and experience the full time evolution of the medium. Understanding bottom quark production in $p+p$ collisions gives a baseline reference for studying larger collision systems. The measurement of the $b\bar{b}$ cross section gives insight into $b$ quark production mechanisms which can directly test pQCD predictions. The $b\bar{b}$ signal can be isolated by taking advantages of $B^{0}$ oscillations in like-sign muon pairs with invariant mass of 5-10 GeV. Measuring like-sign dimuons within this mass range provides an enriched bottom signal with a minimal amount of open charm background and without any contributions from quarkonia or Drell-Yan pairs. $b\bar{b}$ will be measured through the semi-leptonic decay like-sign dimuon signal, in the rapidity range 1.2 $<|y|< $ 2.2 and at $\sqrt{s} = 510$ GeV from data recorded in 2013 at the PHENIX experiment. In this presentation, the status of the $b\bar{b}$ production study will be presented. [Preview Abstract] |
Thursday, November 16, 2017 11:24AM - 11:36AM |
B3.00003: Study of Atmospheric Temperature Variations with Cosmic Ray Flux Measurements Beena Meena, Xiaochun He There is a growing need to develop reliable physical models for determining the variations of the effective atmospheric temperature on a global scale in order to systematically study the trend of dynamical changes of the Earth's atmosphere in real-time. At Georgia State University, we are developing portable, low-cost cosmic ray telescopes and working on establishing an international collaboration that builds a network of cosmic ray detectors around the world for studying the effective atmospheric temperature. One of the key components of this project is to build a statistical model based on a multivariable regression technique using measured cosmic ray muon and neutron flux data to determine the effective temperature. In this talk, we will show the preliminary results of an analysis using cosmic ray data from Yakutsk, Russia and Nagoya, Japan and will compare the predicted effective temperature with the data from the nearby radiosonde measurements. [Preview Abstract] |
Thursday, November 16, 2017 11:36AM - 11:48AM |
B3.00004: Energy Independent Phase Shift Analyses of Light Nuclear Systems Timothy Black, Robert Haun, Chandra Shahi, Fred Wietfeldt, Michael Huber, Muhammad Arif Our research group, which has carried out high precision scattering length measurements of the $n + d$, $n + ^3{\rm{He}}$, and $n + ^4{\rm{He}}$ systems, is now undertaking energy independent phase shift analyses of these systems, as well as the $p + d$ system. The aim of these analyses, which will utilize all extant low energy data for these systems, is to determine scattering lengths, effective range parameters, and shape parameters, as well as spin-mixing parameters, where relevant, in order to help develop uniform NN, 3N and 4N models that also account for charge symmetry and charge independence breaking. Preliminary results will be presented. [Preview Abstract] |
Thursday, November 16, 2017 11:48AM - 12:00PM |
B3.00005: Power of combining large statistics $\gamma$-ray coincidences and mass and Z identified low statistics $\gamma$ data in the A~100-120 region Enhong Wang The power of combining high statistics gamma-ray coincidence data and mass and Z identified low statistics gamma-ray data is illustrated by studying neutron rich nuclei in the A~100-120 region from the 4 fold gamma coincidence data following the spontaneous fission of 252Cf by using Gammasphere, and also from the measurement of the prompt gamma-rays in coincidence with isotopically identified fragments produced by 238U beams on a 9Be target at energies around the Coulomb barrier with VAMOS++ and EXOGAM at GANIL. An excited deformed band was discovered in the spherical ground state of 96Y to indicate the shape coexistence. In 100Y, coexistence of neutron pseudo spin and GM doublet bands have been discovered for the first time. High spin level schemes of 118,119Ag have been established. Theoretical calculations revealed their oblate deformation. The new 2 gamma vibrational bands in 103,107Mo have been found to fill in the odd A gap of an island of 2 gamma vibrational bands in the A~100 region. Clear evidence for chiral doublet bands in 104Mo has been found. Our work on these nuclei are showing the new avenues that are opened up by combining the two experimental approaches to definitively identify the gamma ray associated with particular isotopes. [Preview Abstract] |
Thursday, November 16, 2017 12:00PM - 12:12PM |
B3.00006: Geant4 Simulation of Low-Energy X-rays Xoft Machine Nicolas Recalde In the past decade, miniature X-ray sources developed by Xoft Inc. (an iCad company, Sunnyvale, CA) have become the modality of choice for the treatment of specific cancer lesions. The X-ray spectra of these sources have a typical endpoint of 50 keV. We aim to quantify the energy deposition in matter when using this machine, and one of the first steps is to characterize the X-ray distribution from this source. For that purpose we have done Geant4 simulations of the Xoft X-ray spectrum and compared against precise experimental data obtained at NIST. We found that radiation transport at low energy can be very sensitive to small variations in manufacturing specifications. [Preview Abstract] |
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