Bulletin of the American Physical Society
2011 Annual Meeting of the California-Nevada Section of the APS
Volume 56, Number 14
Friday–Saturday, November 11–12, 2011; Menlo Park, California
Session F1: Nuclear Physics |
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Chair: Karl Van Bibber, Naval Postgraduate School Room: Bldg 48 - ROB Redwood A/B |
Saturday, November 12, 2011 1:00PM - 1:12PM |
F1.00001: Beta-delayed neutron spectroscopy using trapped radioactive ions Ryan Yee, N.D. Scielzo, P.F. Bertone, F. Buchinger, S. Caldwell, J.A. Clark, C.M. Deibel, J. Fallis, G. Li, S. Gulick, D. Lascar, A.F. Levand, E.B. Norman, M. Pedretti, G. Savard, R.E. Segel, K.S. Sharma, M.G. Sternberg, J. Van Schelt, B.J. Zabransky The properties of beta-delayed neutron emission are of interest to both the basic and applied nuclear physics communities. For example, branching ratios are needed to determine how the short-lived neutron-rich isotopes synthesized in the astrophysical r process decay back to stability to become the isotopes we observe today. Also, neutron energy spectra and branching ratios are required for the design of nuclear reactors. Reliable measurements of the beta-delayed neutron properties can be performed with unprecedented precision using an ion trap surrounded by radiation detectors. When a radioactive ion decays in the trap, the recoil-daughter nucleus and emitted particles emerge from the $\sim $1 mm$^{3}$ trap volume with minimal scattering. These properties allow the momentum and energy of the emitted neutron to be precisely reconstructed from the nuclear recoil. Spectroscopy of beta-delayed neutrons can be performed with high efficiency, energy resolutions approaching $\sim $3{\%}, and virtually no background. Results from a recent proof-of-principle experiment will be discussed. Prepared by LLNL under Contract DE-AC52-07NA27344 and ANL under Contract DE-AC02-06CH11357. [Preview Abstract] |
Saturday, November 12, 2011 1:12PM - 1:24PM |
F1.00002: Searching for the Decay and Half Life of the 7.6 eV Excited State in the Thorium-229 Nucleus Erik Swanberg, Jason Burke, Robert Casperson, Rick Norman Thorium-229 has the lowest known nuclear excited state at 7.6 eV [1]. The state has been known to exist for 35 years, but it's decay to the ground state has never been directly observed. Because it has an extremely low energy for a nuclear state, a unique set of applications are possible, including a nuclear clock, a nuclear laser, and investigations into Bound Internal Conversion, Nuclear Excitation by Electronic Transition and Nuclear Excitation by Electron Capture. We are currently conducting experiments to observe the decay and measure it's half life. We use uranium-233 alpha decay as our source of thorium-229 excited nuclei and use several different methods to search for the half life over a range from nanoseconds to days.\\[4pt] [1] Beck et al., PRL 98, 142501 (2007) [Preview Abstract] |
Saturday, November 12, 2011 1:24PM - 1:36PM |
F1.00003: Analysis of fixed target collisions with the STAR detector Brooke Haag Collisions between gold ions in the RHIC beam with aluminum nuclei in the beam pipe provide an unexpected opportunity for analysis of fixed target collisions with the STAR detector at RHIC. Lower energy fixed target collisions extend the low energy reach of the RHIC beam energy scan and possibly improve the chance of finding the critical point of the hadronic to quark matter phase boundary. In this talk, we will present preliminary pion yields from Au+Al collisions at 8.85 AGeV and $\sqrt{s}$ of 4.5 GeV. Comparisons will be made to results from the AGS heavy ion program as well as UrQMD simulations. [Preview Abstract] |
Saturday, November 12, 2011 1:36PM - 1:48PM |
F1.00004: Longitudinal Spin Transfer to $\Lambda$ and $\bar\Lambda$ Hyperons Produced in Polarized Proton-Proton Collisions at $\sqrt{s} = 200$ GeV Ramon Cendejas The longitudinal spin transfer, $D_{LL}$, of $\Lambda$ and $\bar\Lambda$ hyperons in longitudinally polarized proton-proton collisions is sensitive to the polarization of strange quarks and anti-quarks in the polarized proton, as well as polarized fragmentation. The STAR collaboration previously reported $D_{LL}$ from a data sample obtained in 2005 that corresponds to an integrated luminosity of 2 $pb^{-1}$ with 50\% beam polarization. Considerably larger data samples corresponding to 6.5 $pb^{-1}$ and 25 $pb^{-1}$ with beam polarization of 57\% were obtained in 2006 and 2009. The analysis of these data is in progress and is anticipated to widen the kinematic range and considerably improve the precision of the $D_{LL}$ measurements. The status of the analysis will be discussed. [Preview Abstract] |
Saturday, November 12, 2011 1:48PM - 2:00PM |
F1.00005: STAR Extracted Upsilon(1S+2S+3S) Yield from the RHIC 2009 p+p $\sqrt s$ = 200 GeV run Andrew Peterson Upsilon meson production is of particular interest in heavy ion physics because the suppression of excited Upsilon states (2S and 3S) compared to the ground state (1S) is theorized to be one of the best probes of the hot, dense matter produced in relativistic heavy ion collisions. It is expected to be a good test of deconfinement and of the medium temperature. In addition, bottomonia is expected to be less affected than charmonia by recombination and hadronic co-mover absorption. Enhancement or suppression is quantified by the nuclear modification factor $R_{AA}$. The Solenoidal Tracker at RHIC (STAR) detector is used to identify Upsilon $\rightarrow e^-e^+$. $e^-e^+$ from the Drell-Yan (DY) process and b-bbar continuum can also reconstruct to a similar invariant mass (IM) as the Upsilon. The DY and b-bbar backgrounds are determined by fitting a functional form including a parameterization of the trigger activation to the like-sign electron pair IM spectrum. The fit is combined with the Upsilon(1S+2S+3S) line shape to determine the total Upsilon(1S+2S+3S) yield from the $e^-e^+$ IM spectrum. We present preliminary results on the total extracted Upsilon(1S+2S+3S) yield produced in STAR during the Relativistic Heavy Ion Collider (RHIC) 2009 p+p $\sqrt s$ = 200 GeV run. [Preview Abstract] |
Saturday, November 12, 2011 2:00PM - 2:12PM |
F1.00006: Detector Efficiencies of the Dielectron Decay of the Upsilon Meson from a Single Electron Simulation Kurt Hill In the analysis of heavy flavor meson production in high energy hadron collisions, it is important to have an accurate estimation of efficiencies in order to determine total yield. To calculate these efficiencies at the STAR detector, we use a method called embedding in which simulated particles are embedded into real event data. Because the embedding process is computationally intensive and requires a significant amount of time, we have developed a method to simulate the embedding of the dielectron Upsilon decay using only single electron embedding data. This enables us to extract the relevant information without having to generate a new data set, thus saving computation time. We present the motivation, method, and results of extracting Upsilon efficiencies from single electron embedding at STAR. [Preview Abstract] |
Saturday, November 12, 2011 2:12PM - 2:24PM |
F1.00007: ABSTRACT WITHDRAWN |
Saturday, November 12, 2011 2:24PM - 2:36PM |
F1.00008: Studying the $\Lambda p$ interaction with CLAS Alec Thompson, John Price The hyperon-nucleon interaction is of great interest to the nuclear physics community. Its magnitude is related to the well-measured $pp$ interaction by $SU(3)_F$ symmetry, which should simplify its study under the right circumstances. It has great importance to the hypernuclear physics community, with a connection to astrophysics due to its implications on the study of nuclear matter at varying density. As part of a planned program of hyperon-nucleon interactions with the CLAS detector at the Thomas Jefferson National Accelerator Facility, we have begun a study of the $\Lambda p$ interaction. The $\Lambda$ is produced in and tagged by the process $\gamma p\to K^+\Lambda$, where its long mean life ($c\tau=7.89\,\mathrm{cm}$) allows it to interact with secondary protons in the target. This talk will present the motivation, initial results, and future plans of this study. [Preview Abstract] |
Saturday, November 12, 2011 2:36PM - 2:48PM |
F1.00009: Design and Construction of the High Threshold \v{C}erenkov Counter Mirror Assembly for the CLAS12 detector at JLab Harneet Grewal, John Price, Youri Sharabian An overview is presented of the design and construction of the High Threshold \v{C}erenkov Counter (HTCC) mirror assembly to be placed in the forward region of the CLAS12 detector at the Thomas Jefferson National Accelerator Facility (JLab). The $\mathrm{CO}_2$ gas HTCC has a pion momentum threshold of $4.9\;\mathrm{GeV}/c$, and will provide improved pion-electron separation at the higher engeries that will be produced after the JLab 12 GeV upgrade is complete. The location of the HTCC in the forward detector requires that it be built with a minimal amount of material to limit the contamination of the momentum resolution due to multiple scattering events. This talk will demonstrate how this was achieved by using low mass composites. Also presented will be highlights of the innovative geometry of the design as well as the manufacturing process being implemented in order to maximize quality control. [Preview Abstract] |
Saturday, November 12, 2011 2:48PM - 3:00PM |
F1.00010: No blackhole and no atomic bomb Philip Shin Title: c=c(1+1=2) The light speed 1+1=2. So we count the number by step by step for one point. When we count the number by one point, we use the number written on the paper. This means this is not number, but the graph and line. The light speed is the truth in physics. I can prove it by number. 10\%=0.1 As \%=kg So 10kg=0.1 kg=1/10 x 1/10 kg=1/100 And 100\%=1 So kg=100\%/100 kg=\% So 1kg=1\%=1/100 E=mc$^2$ So cx kgx m$^2$/sec$^2$= 1kgx cx m$^2$/sec$^2$ cx 1/100x m$^2$/sec$^2$= 1/100x cx m$^2$/sec$^2$ So c/100=c/100 So c=c And c is the truth never changed. Title: By faith, no blackhole As to be, we glory to God and that is basic theology for christian. And I want to say that BE means just thinking. There is no clue of nature and no proposition to prove it. I just believe by feeling and emotion. I trust that it can be the physic really. There are only human beings and there is no idol that is different existence from human beings, that is true to be. So the nature we see is zero and we, human beings make the zero nature as from no start and no ending. No alpha and omega mean we are idol and that there is no blackhole. Blackhole means the block is existing in the nothing(as we are no alpha and no omega). So the block cannot be existence. So if there is blackhole, then there must be the wall to block me and never walk again. The big bang and evolution mean they are no alpha and no omega and existing by themselves. So they could be existence, but big bang and evolution are just logical fact to be. We need faith as God give us the direction into our spirit. [Preview Abstract] |
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