Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session Y10: Instrumentation II |
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Sponsoring Units: DNP Chair: Matthew Lamont, Brookhaven National Laboratory Room: Garden 1 |
Tuesday, May 3, 2011 1:30PM - 1:42PM |
Y10.00001: A New HRIBF Electron Beam Plasma Ion Source Ronald Goans, Ken Carter, Boyce Griffith, Charles Reed The particle-surface interactions that dominate the effusion of particles through the target/ion source system (TISS) typically require very high temperatures to reduce the release time, particularly for the less volatile species. This high- temperature environment, however, may not be conducive to the efficient formation and transport of molecular sidebands. To investigate and improve the operating conditions necessary to optimize the molecular-sideband technique at the Holifield Radioactive Ion Beam Facility (HRIBF), the standard HRIBF Electron Beam Plasma (EBP) ion source design was modified to allow independent and controlled heating of the transfer line and cathode. The modified TISS was built and the modifications have been characterized. While maintaining the cathode temperature necessary for normal operation of the EBP ion source, the transfer line temperature was varied from about 1300 $^{\circ}$C to 2000 $^{\circ}$C for a target temperature held at 1900 $^{\circ}$C. A complete overview of the new target/ion source parameters will be presented. [Preview Abstract] |
Tuesday, May 3, 2011 1:42PM - 1:54PM |
Y10.00002: Implementation of a high-density multichannel data acquisition system at ORNL for nuclear reaction studies S.H. Ahn, K.L. Jones, M. Matos, D.W. Bardayan, K.Y. Chae, M.S. Smith, R.L. Varner, J.M. Elson, M.A. Famiano A new detector array comprised of 24 double-sided silicon strip detectors has been under development at ORNL in order to measure nuclear reaction products with lower thresholds and better resolution than current detectors. To utilize this new array, we are implementing $\sim$2000 channels of signal processing electronics based on application-specific integrated circuits (ASICs) designed at Washington University. The ASICs handle pulse shaping, timing, triggering, and digitization of 16 channels all on a single chip. To make up 2048 channels, 128 chips will be combined and integrated into the ORNL data acquisition system. Details of the development status, tests with many types of detectors, and future plans will be presented. [Preview Abstract] |
Tuesday, May 3, 2011 1:54PM - 2:06PM |
Y10.00003: Geant4 Simulation of HRIBF Fission-Tracking Detector Z. Kohley, C.J. Gross, J.F. Liang, D. Shapira, R.L. Varner Construction of a new detection system, for the study of fission-like products resulting from the collisions between neutron-rich radioactive ion beams and heavy targets around the Coulomb barrier, is underway. The detector is designed to provide information on the energy, angle, and charge of the fragments. The detector consists of an ionization chamber (IC) with a segmented anode structure and single wire proportional counters. Silicon and CsI(Tl) detectors placed on the walls of the IC will be used for collection of the residual energy of the fragments. The 3-D tracking and particle identification (PID) abilities of the detector have been modeled using Geant4. The Magboltz code was used to simulate the drift of the electrons in the IC and the results where incorporated into the Geant4 model. The simulation demonstrated that accurate 3-D tracking of the fragments is required to obtain PID from $\Delta$E-E plots because the anode signals ($\Delta$E) need to be scaled by the distance the fragment traveled under the anode. The 3-D tracking accuracy and PID resolution of the detector, based on the Geant4 simulation, will be presented. Additionally, the statistical-model program GEMINI++ has been used as an input to the Geant4 simulation and will allow for the fission event efficiency of the detector, for different reaction systems, to be determined. [Preview Abstract] |
Tuesday, May 3, 2011 2:06PM - 2:18PM |
Y10.00004: The Oak Ridge Isobar and Isomer Separator and Spectrometer (ORISS) Andreas Piechaczek, J.C. Batchelder, H.K. Carter, C.A. Reed, O. Yair, V. Shchepunov, E.F. Zganjar, A. Blalock, S. Berridge, R. Todd, G. Armstrong, K. Omoumi, A.R. Fleury, Y. Hu ORISS is an electrostatic high-resolution isobar and isomer spectrometer and separator to provide pure beams for decay spectroscopy of exotic nuclei. It consists of an RFQ, low emittance, ion cooler and buncher, a multi-pass time-of-flight spectrometer, and a time-of-flight detector to register time-of-flight spectra, or a Bradbury Nielsen (BN) gate to physically separate isobars and isomers of interest. Presently, ORISS uses an off-line ion source. Ion bunches as short as 8 ns FWHM have been produced in the buncher, and a BN gate with transition times open/closed of 15 ns was built. These results of individual component tests together with ion optical calculations predict a mass resolving power of 400,000 and transmission of 50{\%} for the completed system. In the future, radioactive ions from the Holifield Radioactive Ion Beam Facility at ORNL will be injected. Results of first test measurements of the complete off-line system will be presented. [Preview Abstract] |
Tuesday, May 3, 2011 2:18PM - 2:30PM |
Y10.00005: Forward Vertex (FVTX) detector for PHENIX experiment Sergey Butsyk The PHENIX detector at the Relativistic Heavy Ion Collider (RHIC) has been built with a strong heavy quark particle identification capability. These unique probes of matter are essential to adequately understand in-medium energy loss and to test the basic properties of QCD. The current PHENIX heavy flavor physics program will be significantly enhanced by the addition of the Forward Silicon Vertex upgrade detector (FVTX) in the acceptance of the existing Muon Arm detectors ($1.2 < |y| < 2.4$). Each arm of the FVTX detector consists of 4 disks of silicon strip sensors combined with FPHX readout chips and provides a precision measurement of the radial coordinate of the charged particle track. The fully assembled detector will consist of more than 1 million readout channels. The detector is planned to be put into operation in FY2012. I plan to present the overview of the detector design, demonstrate the importance of the FVTX upgrade for the future of the RHIC heavy quark program and will concentrate on the current status of the detector construction. [Preview Abstract] |
Tuesday, May 3, 2011 2:30PM - 2:42PM |
Y10.00006: How to improve reaction plane measurement via the combination of multiple detectors? Xiaoyang Gong Determining reaction plane plays a central role in various heavy ion analyses as it directly characterizes the non-trivial initial geometry for a collision. Multiple reaction plane detectors, the performances of which are estimated by reaction plane correction factors (resolution factors), are installed at most of current RHIC experiments. They are situated at different rapidity ranges and are mainly used for systematical cross-checks of elliptic flow measurement. In this talk, we aim to improve the RP resolution factor by combining information provided by two or more reaction plane detectors. The mathematic framework is formulated; AMPT simulation is used to demonstrate the robustness of the method. [Preview Abstract] |
Tuesday, May 3, 2011 2:42PM - 2:54PM |
Y10.00007: Status of the PHENIX VTX Upgrade John Koster The recently completed vertex tracker (VTX) was installed into the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) in November, 2010. The VTX will enable new measurements at PHENIX of displaced vertices from the decay of charm and bottom, and improve the reconstruction of jets with its large acceptance. These enhanced capabilities will allow PHENIX to further improve its measurements of nucleon spin-structure and heavy quark propagation through the hot-dense medium created in Au+Au collisions at RHIC. The VTX consists of four layers: inner two detector layers made of pixel sensors and outer two of ``stripixel'' sensors. This presentation will describe the upgrade and its performance in its first RHIC run. [Preview Abstract] |
Tuesday, May 3, 2011 2:54PM - 3:06PM |
Y10.00008: Charmed Meson Reconstruction Using Micro Vertexing Technique and Silicon Trackers in STAR Experiment at RHIC Jaiby Joseph Charm quarks are produced during the early stages of collision, making it a powerful probe of the hot and dense medium created at RHIC. Its measurement through the semi-leptonic decay channel can provide some insight, although the relative yield of charm and bottom are highly uncertain in such measurements. It is essential to disentangle charm and bottom yields experimentally to understand the observed suppression at high pT in central Au+Au collisions. A direct measurement of charm can separate the c contribution and resolve this ambiguity. Measurements of charm elliptic flow ($v_{2}$) can give us pivotal information on the medium properties. We use a microvertexing technique for the direct reconstruction of $D^{0}$ and $\bar{D^{0}}$ through the decay channel $K^{\mp}\pi^{\pm}$ in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}=200$GeV at RHIC in the year 2007 and 2005. This method uses a kinematically constrained fit for secondary vertex reconstruction. The datasets were collected with Silicon Drift and Silicon Strip detectors, and their pointing capabilities are crucial for this analysis. Preliminary results on neutral D-meson measurements will be presented. [Preview Abstract] |
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