Bulletin of the American Physical Society
74th Annual Meeting of the Southeastern Section
Volume 52, Number 13
Thursday–Saturday, November 8–10, 2007; Nashville, Tennessee
Session EB: Nuclear and Particle Experiment |
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Chair: Brad Plaster, University of Kentucky Room: Scarritt-Bennett Center Laskey C |
Thursday, November 8, 2007 3:45PM - 4:15PM |
EB.00001: The US Dark Matter Direct Detection Program Invited Speaker: Recently, the joint HEPAP/AAAS DMSAG (Dark matter Scientific Assessment Group) outlined a strategy for the future of dark matter direct detection. I will discuss the motivations for dark matter detection, possible DM candidates from theory, and the variety of techniques proposed to push the search forward into the most interesting regimes of parameter space. These techniques include cryogenic detection, detection via noble liquids, and directional detection. Coupled with results from LHC in the next few years, we may be on our way to revealing the identity of the mysterious dark matter particle. [Preview Abstract] |
Thursday, November 8, 2007 4:15PM - 4:27PM |
EB.00002: The NPDGamma Experiment at the SNS FnPB Christopher Crawford The NPDGamma experiment recently concluded a successful first phase data-taking run at LANSCE and is now moved to ORNL where it has been approved to run as the first experiment at the Fundamental Neutron Physics Beamline at the SNS. To accommodate the SNS beam and lessons learned at LANSCE, a number of changes have been proposed for the experiment. I will describe these improvements and upgrades, and the expected performance of the experiment to measure the parity-violating directional gamma asymmetry $A_\gamma$ of the reaction $\mbox{n} + \mbox{p} \to \mbox{d} + \gamma$ with an error of $1\times10^{-8}$. [Preview Abstract] |
Thursday, November 8, 2007 4:27PM - 4:39PM |
EB.00003: First reconstruction results on the alignment of muon endcap chambers in the CMS experiment Samir Guragain, Gyongyi Baksay, Marcus Hohlmann The muon endcaps in the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider are being aligned by a hardware system that employs analog and optical sensors. The system is now fully instrumented with optical 2-D sensors based on linear CCDs and illuminated by cross hair lasers in 15 m long Straight Line Monitors across the disks in both muon endcaps. Analog sensors such as R-sensors, Z-sensors, proximity sensors, and inclinometers are also used to align the muon endcap system for the first LHC run expected early next year. We briefly present an overview of the alignment system and focus on first results on the reconstruction of chamber positions and orientations using data taken during the CMS magnet test in 2006 and during commissioning in 2007. Reconstructed positions are compared against independent results from photogrammetry and survey analysis under field-off conditions. [Preview Abstract] |
Thursday, November 8, 2007 4:39PM - 4:51PM |
EB.00004: Performance of the PHENIX Multi-Gap Resistive Plate Chamber Time-of-Flight Detector Ronald Belmont In Run7 of RHIC the PHENIX experiment operated a Time-of-Flight detector based on Multi-Gap Resistive Plate Chamber technology. The detector covers an area of 8 $m2$ in the PHENIX West arm spectrometer and has an intrinsic timing resolution of $\sigma_t ~ 80$ ps. In conjunction with the Aerogel Cherenkov Counters (ACC), it allows for 4 $\sigma$ $\pi/K$ separation up to $p_T ~ 3$ GeV/$c$ and $K/p$ separation up to $p_T ~ 5 $ GeV/$c$. Combined with the ACC, the new detector system provides seamless particle identification (PID) for $\pi/K/p$ in the range $0.2< p_T < 9$ GeV/$c$, and for hadronic resonances the PID has been extended even higher ($p_T > 10$ GeV/$c$ ). Furthermore, the track-by-track identification with increased angular coverage allows for jet correlation measurements with PID in both the near side and away side jet cones. Jets in heavy ion collisions at RHIC have been shown to be significantly modified when compared to the p+p reference data, and Identified particle measurements at high $p_T$ are fundamental to understanding the underlying jet suppression mechanisms. The MRPC-TOF performance and the consequential extended physics capabilities of PHENIX will be discussed. [Preview Abstract] |
Thursday, November 8, 2007 4:51PM - 5:03PM |
EB.00005: Near-Real Time, Large-Volume Reconstruction of PHENIX Data Using High Throughput GRID Networking Brian Love Near-real time reconstruction of a large volume (25 TBytes) of raw data from the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) has been sustained for several weeks using CPU resources of the ACCRE computing facility at Vanderbilt University. The data transfers to and from the Brookhaven National Laboratory (BNL), where RHIC is located, utilized the Open Science GRID infrastructure. Raw data files were transferred daily from RHIC to ACCRE, where, through an automated pipeline, these files were processed and the output returned to BNL. At ACCRE we developed fault tolerant mechanisms to ensure a robust transfer operation. To streamline control of the production pipeline, we implemented a dynamic Web-based Monitoring application. Additionally, with the incorporation of GRID networking into the fabric of the PHENIX data production system, we confirm the ability to combine computing resources from diverse geographical locations. [Preview Abstract] |
Thursday, November 8, 2007 5:03PM - 5:15PM |
EB.00006: Hyperdeformation in the Z=40-60 part of nuclear chart C.W. Jang, A.V. Afanasjev, J. Begnaud Superdeformed shapes are well known in finite nuclei and theory predicts the existence of more elongated shapes. However, the experimental search at high spin for new type of nuclear shapes called hyperdeformed (HD) and characterized by the 3:1 semiaxis ratio has not been successful so far. On the other side, the recent investigation of the very extended shapes in $^{108}$Cd have renewed interest in the study of hyperdeformation. Also, the ridge-structures in 3-dimensional rotational mapped spectra in the A$\sim $120 mass region are compatible with features of hyperdeformation [1]. The systematic investigation of the high-spin hyperdeformation in the Z=40-60 has been performed within the framework of the cranked relativistic mean field (CRMF) approach [2]. The calculations have been compared with the experimental data on ridge-structures in the A$\sim $120 mass region. General features of this type of nuclear shapes and rotational structures built on top of them will be discussed. Our presentation will also outline the regions of nuclear chart where the search for HD shapes should be concentrated. [1] B. Herskind et al, Phys. Scripta T125, 108 (2006), [2] A. V. Afanasjev et al, Nucl. Phys. 608 (1996). [Preview Abstract] |
Thursday, November 8, 2007 5:15PM - 5:27PM |
EB.00007: Search for the electron antineutrinos from the Sun at KamLAND Oleg Perevozchikov KamLAND is 1kton liquid scintillator detector located deep underground in Japan. It was build to study antineutrinos produced by nuclear plants, but it can also detect antineutrinos from other sources. Chain of thermonuclear reactions on Sun is a huge source of electron neutrinos. Detection of electron antineutrinos from Sun, which are not directly produced there, could indicate the existence of the mechanism of conversion electron neutrinos to electron antineutrinos under influence of strong magnetic field in the core of the Sun. Update of the first KamLAND result on search of such mechanism will be presented. [Preview Abstract] |
Thursday, November 8, 2007 5:27PM - 5:39PM |
EB.00008: g-factors in Neutron Rich Ce and Nd Isotopes C. Goodin, A.V. Ramayya, N.J. Stone, K. Li, S. Liu, A.V. Daniel, J.H. Hamilton, J.K. Hwang, Y.X. Luo, J.O. Rasmussen, M.A. Stoyer, S.J. Zhu, G.M. Ter-Akopian, I.Y. Lee, J.R. Stone We have recently developed a method for measuring the g-factors of excited states of neutron rich fragments produced in the spontaneous fission of $^{252}$Cf. With this method, we are able to determine angular correlations between prompt gamma-rays emitted from the fragments. The determination of g-factors is accomplished by measuring the attenuation of the expected angular correlation, caused by the interaction of the fragment with the randomly oriented hyperfine fields of an un-magnetized iron foil. Using our high statistics data set ($\sim$ 4 $\times$10$^{11}$ triple coincidence events), we have measured the previously unknown g-factors of the 4$^+$ state in $^{150}$Nd and the 6$^+$ state in $^{152}$Nd. We have also re-measured g-factors of the 2$^+$ states in $^{146,148}$Ce, significantly reducing errors. We will show that, in each case, the g-factor agrees with the limiting value for a pure rotational state. [Preview Abstract] |
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