Bulletin of the American Physical Society
2006 Division of Nuclear Physics Annual Meeting
Wednesday–Saturday, October 25–28, 2006; Nashville, Tennessee
Session GH: Instrumentation II |
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Sponsoring Units: DNP Chair: Joe Hamilton, Vanderbilt University Room: Gaylord Opryland Cheekwood F |
Saturday, October 28, 2006 9:00AM - 9:12AM |
GH.00001: Position Resolution for PHENIX Muon Resistive Plate Counter Ruizhe Yang A new 1$^{st}$ level muon trigger is being developed for the PHENIX experiment at Brookhaven National Laboratory. The trigger will be based on two fast momentum sensitive spectrometers using Resistive Plate Counters (RPC) for charged particle detection. The spectrometers will utilize RPC technology developed for the CMS experiment at CERN. Position resolution measurements of RPC prototypes have been carried out with cosmic rays. In this talk, we will discuss the position resolution which can be achieved with the PHENIX muon trigger RPCs. [Preview Abstract] |
Saturday, October 28, 2006 9:12AM - 9:24AM |
GH.00002: Multi-Gap Resistive Plate Chamber (MRPC) for the PHENIX TOF upgrade Hugo Valle The PHENIX experiment has observed enhanced proton/pion ratios in central Au+Au collisions as compared to the expectation from parton fragmentation. The measurements have been done using the scintillator based Time-of-Flight (TOF) detector in the PHENIX East arm, which~ allowed pi/K and K/p separation up to pt = 2.5 and 4 GeV/c respectively. Particle identification (PID) to higher pt ($>$ 8 GeV/c) is needed to better characterize the hadron production mechanism at intermediate and high-pt and differentiate between competing theoretical descriptions. The PHENIX detector is being upgraded with a high-pt PID system. A cost-effective TOF system based on Multi-gap Resistive Plate chambers (MRPC) has been implemented as part of this upgrade. The MRPC-TOF will provide high-resolution timing measurement in the PHENIX West arm. It will supplement the PID provided by the Aerogel and Ring Imaging Cerenkov Counters, and allow for seamless particle identification in the range 0.2 $<$ pT $<$ 9 GeV/c. Three different prototypes were installed and operated in heavy ion beam conditions during RUN5. The design goal of sigma\_t $\sim $ 100 ps has been achieved. The final TOF-MRPC detector will be installed and ready for operation for RUN7. The details on the MRPC design and the electronics chain will be presented. [Preview Abstract] |
Saturday, October 28, 2006 9:24AM - 9:36AM |
GH.00003: RPC Prototypes for the PHENIX Forward Muon Trigger Upgrade at RHIC Jun Ying The PHENIX collaboration at RHIC plans to build a fast muon trigger system for the PHENIX detector based on Resistive Plate Chamber [1] (RPC) technology to determine $W$ boson production cross sections and single spin asymmetries at $\sqrt{s} = 500$~GeV by detecting decay muons at forward and backward rapidities. Several prototypes have been built and tested using cosmic ray in order to understand the RPC performances like time resolution, trigger efficiency, power consumption etc. The results are reported here. \newline \newline [1] R.Santonico and R.Cardarelli, {\sl Nucl.\ Instr.\ and\ Meth. } {\bf 187} (1981) 377. [Preview Abstract] |
Saturday, October 28, 2006 9:36AM - 9:48AM |
GH.00004: Detection Efficiency of the Modular Neutron Array T. Baumann, W.A. Peters The Modular Neutron Array (MoNA) has been designed as a high-efficiency large-area detector array for neutrons stemming from reactions of fast rare isotope beams. In its current setup, it is optimized for neutron energies between 30 and 100~MeV. MoNA consists of 144 detector modules of plastic scintillator. Two methods to gather experimental data on the detection efficiency were used, one by employing the breakup reaction of $^{11}${Be} into $^{10}${Be} plus a neutron, and one by comparing the response of MoNA to an additional liquid scintillator neutron detector. These experimental data will be presented together with simulated detection efficiencies. [Preview Abstract] |
Saturday, October 28, 2006 9:48AM - 10:00AM |
GH.00005: A prototype, high-efficiency, position sensitive neutron detector for the proposed neutron spin rotation experiment at the SNS D.M. Markoff, V. Cianciolo, C.L. Britton, R.G. Cooper, R.J. Warmack We are developing a position sensitive ($\sim$ 1 cm resolution) neutron detector with nearly 100\% efficiency for use at the high flux ($> 5 \times 10^{10}$ neutrons/sec) pulsed beam at the Oak Ridge Spallation Neutron Source (SNS). The prototype detector is important for transmission experiments such as the proposed parity-violating neutron spin rotation in hydrogen measurement. The detector concept integrates the segmented $^3$He ionization chamber designed for the preliminary spin-rotation in helium experiment\footnote{S.D. Penn {\em et al.}, Nucl. Instr. and Meth. {\bf 457} 332 (2001)} and the position sensitive, charged particle collection technology currently being developed at ORNL for low-efficiency beam-transmission monitors for the SNS\footnote{C.L. Britton et al., IEEE Trans. Nucl. Sci., 51, 1016 (2004).}. Neutron absorption on $^3$He produces $^1$H and $^3$H that pass through a wire grid producing an $e^-$ shower detected in current mode by wire strips mounted on a substrate. For 100\% efficiency, regions are created with a series of high-voltage plates, grids, and wire strips each strategically located along the beam axis. Analysis over several regions with alternating wire strip orientation provides a two-dimensional beam profile. We will present our prototype model and test results. [Preview Abstract] |
Saturday, October 28, 2006 10:00AM - 10:12AM |
GH.00006: Cosmic Muon Detection using the NSCL Modular Neutron Array W.F. Rogers, S. Mosby, E. Mosby, J. Gillette, M. Reese The NSCL Modular Neutron Array (MoNA), constructed by a multi-institution collaboration (including several undergraduate colleges), was designed and constructed for the study of nuclei near the neutron dripline. During offline periods we've developed a program for use of MoNA for monitoring the long-term behavior of the cosmic muon angular flux distribution. The top and bottom layers of the array (each consisting of nine 2-m long position-sensitive scintillator detectors) are used to optically image the 2-dimensional muon flux distribution over a wide angular range of the sky. Continuous data acquisition is divided into hourly runs, locked to the sidereal clock. Of particular interest are time-dependent north-south and east-west asymmetries in the flux distribution, both long term trends as well as values binned into 24 solar and sidereal hours, and long time variation in the total integrated flux. The accumulated cosmic muon data is also used to track individual muons through the array in order to accurately position-calibrate all of the array detectors for use in accelerator experiments. Undergraduate students developed the coding for optical imaging and associated efficiency corrections for the device, and conducted analysis on stored data. Results will be presented. [Preview Abstract] |
Saturday, October 28, 2006 10:12AM - 10:24AM |
GH.00007: The new PHENIX Reaction Plane Detector at RHIC Eric Richardson Determining event anisotropy is a key method used in the
investigation of the hot dense partonic matter created at RHIC.
The $v_{2}$ measurements of rare observables such as electrons,
photons, $J/\psi$, and high $p_{T}$ particles provide rich
information about the properties of this matter. Previous $v_{2}$
studies have been limited by statistics and reaction plane
resolution. The installation of the new reaction plane detector
at PHENIX will improve the reaction plane resolution in heavy ion
collisions by a factor of 2 to $ |
Saturday, October 28, 2006 10:24AM - 10:36AM |
GH.00008: The PHENIX Muon Piston Calorimeter John Koster The Muon Piston Calorimeter (MPC) is a new electromagnetic calorimeter which has been integrated into the muon forward spectrometers of the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The calorimeter acceptance is $2\pi$ in azimuth and $3.1<\eta<3.65$ in pseudorapidity. The MPC uses PbWO$_{4}$ scintillator crystals with APD readout developed for PHOS as part of the ALICE experiment at CERN. We present an overview of the detector, results from beam tests at the Meson Test Beam Facility at Fermi National Laboratory and first results from the operation of the MPC during the 2006 RHIC run. [Preview Abstract] |
Saturday, October 28, 2006 10:36AM - 10:48AM |
GH.00009: Understanding Release from Actinide Targets -- Recent Results from RIB Development Andreas Kronenberg, H.K. Carter, E.H. Spejewski, D.W. Stracener Development of ion beams of short-lived isotopes is crucial for modern nuclear structure and nuclear astrophysics. The Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory uses the ISOL (Isotope Separation Online) technique to provide radioactive ion beams. So far, uranium carbide has been used as a target to produce neutron-rich fission fragments. Thermodynamic calculations indicate the possibility of in-situ chemical side band formations of volatile species of refractory metals, such as V and Re. These elements release out of oxide targets after production in a nuclear reaction, and can occur only through in-situ formation of their volatile oxide. These have been confirmed experimentally. The results from recent, more detailed investigations of ThO2, UB4 and other actinide targets as well as conclusions from systematic studies will be presented. This research was sponsored by the NNSA under Stewardship Science Academic Alliance program through DOE Cooperative Agreement {\#} DE-FC03-3NA00143. [Preview Abstract] |
Saturday, October 28, 2006 10:48AM - 11:00AM |
GH.00010: On Line Yield Measurements of UC Targets H.K. Carter, E.H. Spejewski, A. Kronenberg, D.W. Stracener, W. Talbert, H.-H. Hsu, J. Nolen, J. Greene, T. Burtseva Actinide targets, especially UC, are being used in current radioactive beam facilities to provide neutron rich beams. For future facilities, especially high power, two-step, neutron-generator configurations, requirements such as thermal conductivity and release of a wide variety of beams must be satisfied simultaneously. A set of three different UC targets varying in particle size have been prepared by ANL and the release properties measured at the HRIBF at ORNL. Using the UNISOR on line test facility which utilizes low intensity protons we have measured, for over 20 elements and 4 to 8 isotopes per element, the yields (atoms / sec) for each of these targets. We find that the yields for the different target materials are within a factor of 10 of each other however this difference is important both in the selection of target material and understanding the reasons for the different yields. The results of yield measurements will be presented with a discussion of our understanding of the processes. [Preview Abstract] |
Saturday, October 28, 2006 11:00AM - 11:12AM |
GH.00011: The Polarized $^3$He Target for the Measurement of $G_E^n$ at high $Q^2$ in Hall A Ameya Kolarkar In early 2006, the Jefferson Lab experiment E02-013 successfully collected data to measure the neutron electric form factor $G_E^n$ at the four-momentum transfer values in the range of 1.2 to 3.5~(GeV/c)$^2$. It used a polarized $^3$He target and a polarized electron beam at energies up to 3.2 GeV to study the semi-exclusive $^3\hspace*{-1.2pt}\vec{H\hspace*{-1.2pt}e} (\vec{e},e^\prime n)$ scattering reaction in quasi-elastic kinematics. The electrons were detected in the BigBite spectrometer and the recoiling neutrons in an array of scintillators. The data will be used to extract $G_E^n$ from the transverse asymmetry $A_T$. The expected statistical accuracy for $\Delta G_E^n/G_{Dipole}$ is 0.04 for these values of $Q^2$. To reduce the systematic uncertainties in $A_T$, the magnetic field direction was measured to better than 2 mrad with a newly developed air-floated compass. For the first time at JLab, the $^3$He target was polarized using spin-exchange with rubidium \emph{and} potassium. A uniform magnetic field was generated in the target region by a newly developed iron enclosure. Nuclear Magnetic Resonance (NMR) and Electron Paramagnetic Resonance (EPR) techniques were used to measure target polarization. Polarizations in excess of 50\% were achieved during running conditions. This talk will focus on various aspects of the target. [Preview Abstract] |
Saturday, October 28, 2006 11:12AM - 11:24AM |
GH.00012: The Neutron Detector for the Measurement of $G_E^n$ at high Q$^2$ in Hall A Jonathan Miller Data collection for an asymmetry measurement of the electric form-factor of the neutron, $G_E^n$, was completed during the spring of 2006 in Hall A at the Thomas Jefferson National Accelerator Facility. To detect the neutron from the quasi- elastic $\overrightarrow{{}^{3}He}(\overrightarrow{e},e' n)$ reaction, a large neutron detector was constructed with an active frontal area of 11.25 m$^2$. The techniques of the construction and the operation of the 1432 channel and 83 ton detector will be discussed. The achieved timing resolution and neutron detection efficiency, both critical for identifying the quasi-elastic neutrons, will be shown. [Preview Abstract] |
Saturday, October 28, 2006 11:24AM - 11:36AM |
GH.00013: The BigBite Spectrometer: Tracking and Optics for the Measurement of $G^{n}_{E}$ at High $Q^2$ in Hall A Seamus Riordan The $G^{n}_{E}$ experiment, a measurement of the electric form factor of the neutron between the $Q^{2}$ range 1.2 to 3.5~$\mathrm{GeV}^2$ through $\vec{e}(\vec{{}^3He},e'n)$ has been carried out in Jefferson Lab's Hall~A. This experiment was made possible by the arrival of the BigBite spectrometer, a non-focusing large momentum and angular acceptance spectrometer. With a recently constructed detector package in BigBite, efforts are now being made to understand and optimize the reconstruction of charged particle tracks and momenta. The data taken during $G^{n}_{E}$ provide a good opportunity for understanding the behavior and performance of the spectrometer. However, identifying tracks from charged particles accurately and efficiently is especially challenging given the high background rates up to 20 MHz at the detectors. Results showing the performance of the track reconstruction and the momentum resolution of the spectrometer will be presented. [Preview Abstract] |
Saturday, October 28, 2006 11:36AM - 11:48AM |
GH.00014: The BigBite Drift Chambers for the Measurement of $G_E^n$ at High $Q^2$ in Hall A Brandon Craver A precision measurement of the electric form factor of the neutron $G^{n}_{E}$ has been carried out in Jefferson Lab's Hall~A for $Q^{2}$ values of 1.2 to 3.5~$\mathrm{GeV}^2$ using a highly polarized $^3$He target and the quasi-elastic semi-exclusive $^3\vec{He}\left(\vec{e}, e^{\prime}n \right)$ reaction. The experiment detected the ejected neutron with an array of scintillators and the scattered electron with the newly commissioned BigBite spectrometer. This new spectrometer has a large angular acceptance (80 msr), complementing the existing 6 msr high-resolution spectrometers, and will enable a new generation of low-rate experiments with lower resolution requirements. A package of three multi-wire drift chambers was constructed in order to allow the spectrometer to operate under high rate conditions and achieve a spatial resolution of $\sigma~\sim~200~\mu m$. Novel construction techniques used for the drift chambers will be discussed. Online results showing chamber performance at raw hit rates up to 20 MHz per plane will be presented. [Preview Abstract] |
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