Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session EH: Instrumentation III |
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Chair: Darek Seweryniak, Argonne National Laboratory Room: Hilton Kona 2/3 |
Thursday, October 25, 2018 7:00PM - 7:15PM |
EH.00001: R&D status of the ALERT recoil particle detector Gabriel Charles ALERT, A Low Energy Recoil Tracker is a detector that will track and identify recoil nuclei fragments at CLAS12, Jefferson Laboratory. It will reconstruct protons with a minimum momentum of about 70 MeV/c and identify all particles with a mass between the proton and the alpha. The detectors composing ALERT have also been selected to be included in the trigger to ensure a fast event selection. This presentation will focus on the state of our R&D for this project as well as the expected performance obtained from simulations. |
Thursday, October 25, 2018 7:15PM - 7:30PM |
EH.00002: Development of the S-2S spectrometer and the fiber target for high-resolution spectroscopic study of the Xi-hypernuclei Takuya Nanamura, Tomofumi Nagae, Shunsuke Kanatsuki, Toshiyuki Gogami, Hiroyuki Fujioka, Hiroyuki Ekawa, Erina Hirose, Ryotaro Honda, Yudai Ichikawa, Masaya Ichikawa, Toshiyuki Takahashi, Hitoshi Toshiyuki Spectroscopic study of Xi-hypernuclei provides insights into the Xi-N interaction. |
Thursday, October 25, 2018 7:30PM - 7:45PM |
EH.00003: Performance evaluation of Time Projection Chamber for LEPS2/SPring-8 Ryo Kobayakawa SPring-8 is one of the largest synchrotron radiation facility in the world. LEPS2 is a beamline of SPring-8, which provides the gamma ray beam in the energy range of 1.5 to 3 GeV for the hadron photoproduction experiments. We are planning to the various hadron production experiments at LEPS2 using LEPS2 spectrometer. The detectors of LEPS2 spectrometer are installed in the solenoid magnet. The detectors development is now undergoing. Time Projection Chamber (TPC) is the central detector, The target is installed in the TPC, and the TPC detects the track of charged particles scattered in polar angle range of 50 to 110 with respect to the target. The TPC for LEPS2 (LEPS2TPC) is a hexagonal shape. The diameter of the sensitive area is1190 mm, and the maximum drift distance is 710 mm. The signals from TPC are read through 10422 pads. We performed the test experiments to evaluate the performance of LEPS2TPC by using gamma ray beam at LEPS2. We analyzed this data and evaluated the detection efficiency of TPC and the drift length dependence and angle dependence of the position resolution of TPC. In this presentation, we report the performance LEPS2TPC.
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Thursday, October 25, 2018 7:45PM - 8:00PM |
EH.00004: Development of an aerogel Cherenkov counter for the LEPS2/SPring-8 experiment to search for the $K^- pp$ bound state Chihiro Yoshida, Hiroaki Ohnishi, Atsushi Tokiyasu, Masaru Yosoi, Masayuki Niiyama, Hitoshi Katsuragawa, Toshiyuki Gogami The kaon bound nuclear system has been studied extensively to understand dense nuclear matter, particularly neutron stars. The $K^- pp$ bound state is the simplest kaonic nucleus and many experiments to search for this bound state have been performed by using various reactions. However, the existence of this bound state has not been established yet. To obtain more detailed information on the the $K^- pp$ bound state, we plan a new experiment via the $\gamma d \rightarrow K^+ \pi ^- X$ reaction at LEPS2/SPring-8. Produced particles are detected with the LEPS2 large acceptance spectrometer in a solenoid magnet. For $¥pi /K$ separation in the high momentum region more than 1.0 GeV/c, we plan to use an aerogel Cherenkov counter (AC). The geometry of a prototype has been determined by using an optical simulation code, guide-7. Based on a result of the simulation, the first prototype detector was constructed. We present the design of the detector, and performance test of the first prototype. |
Thursday, October 25, 2018 8:00PM - 8:15PM |
EH.00005: The Development of 2 m long multi-gap RPC for LEPS2 experiment Ken Watanabe, Masayuki Niiyama, Masaru Yosoi, Shintaro Tanaka We developed multi-gap RPCs with 2 m long strips for LEPS2 experiment. LEPS2 experiment at the SPring-8 in Japan aims to study hadron physics from photo-production reactions. The High rate, high energy and high polarization γ beam irradiates a target. We detect the produced particles by a solenoid spectrometer covering the polar angle region of 5-120 degrees. The 2m long RPCs will be installed into the solenoid magnet cylindrically, which are 0.9m away from the target. They are used as Time-of-Flight (TOF) counters for particle identification (π/K/p). These RPCs are required below 75 ps time resolution (σ) for 3 σ separation. In the previous work, we achieved around 50 ps resolution of 1 m long RPCs. We also developed 2 m RPCs having 65 ps resolution. But since oscillation of preamp often occurred, it was difficult to operate this 2 m chamber stably. We improved the ground around the preamps and we succeeded the noise suppression. In added, we changed several points. We studied the performance of these chambers. We find that they have about 60 ps resolution and over 99% efficiency. In this presentation, I will talk about several improvement and the performance test. |
Thursday, October 25, 2018 8:15PM - 8:30PM |
EH.00006: Evaluation of particle identification performance in the Belle II experiment with the first collision data Hikari Hirata, Dmitrii Neverov, Toru Iijima, Yuji Kato The Belle experiment - an electron-positron collider B factory experiment - discovered new hadrons, such as exotic states and charmed baryons. The upgraded Belle II experiment has started taking collision data in April 2018. We are going to take a factor of 50 more data than the Belle experiment, thanks to the increase in the instantaneous luminosity. The much larger dataset will increase the capability to discover new hadrons and precisely measure their properties. In these studies, the identification of charged pions, kaons, and protons is essential to reduce massive backgrounds. The Belle II experiment introduced new Particle Identification (PID) detectors based on Ring Imaging Cherenkov technologies: a Time Of Propagation counter and an Aerogel-RICH counter. These detectors provide us with higher PID performance, which we have to understand in detail. In this work, PID performance was evaluated using D*+ and Λ decays, which provide high-purity pion, kaon, and proton samples and can be selected without using PID information. An overview of the performance for the individual sub-detectors and for the combination of all the sub-detectors using the first collision data will be presented. |
Thursday, October 25, 2018 8:30PM - 8:45PM |
EH.00007: A new design of MRPC detector by placing a ground layer and pad shape modification Yasuo Miake, Tatsuya Chujo, Motoi Inaba, Hiroyuki Sako, Kyoichiro Ozawa, Toshihiro Nonaka, Masahiro Takamura
One of the goals of high energy heavy ion collisions is to study the QCD phase diagram and the properties of the Quark-Gluon Plasma. J-PARC in Japan (a proposed future program) is focusing on the high baryon density region of the phase diagram and also the search of the critical point in the phase transition. In these heavy ion collisions, charged particle identification is needed. In this abstract we focus on the Time-of-Flight (TOF) detector in order to identify the different particle species. The current proposal is focused to use Multi-Gap Resistive Plate Chambers (MRPC) technology to achieve good timing resolution at J-PARC E-16 experiment. In E-16, 30 ps of timing resolution is required for particle identification. To achieve good timing resolution, impedance-matched and reflection-suppressed signal transmission is needed. Electromagnetic simulation is the solution for such a pad design, and rigid ground layer is necessary for accurate simulation. Our main challenge of MRPC is to place rigid ground and sophisticate the pad shape. In this talk, the current R&D focused on these improvements and the results of the status will be presented. |
Thursday, October 25, 2018 8:45PM - 9:00PM |
EH.00008: Characterization of a tritium target through elastic scattering measurements Noritaka Kitamura, Kathrin Wimmer, Peter Bender, Greg Hackman, Jack Henderson, Nobuaki Imai
Two-nucleon transfer reactions are a powerful tool for studying two-nucleon correlations. Among them, (t,p) two-neutron transfer reactions are suited to probe the pairing interactions in neutron-rich nuclei owing to the simple structure and the neutron excess of the triton. From an experimental point of view, (t,p) measurements on unstable nuclei are challenging as the measurements have to be performed in inverse kinematics and thus require a tritium target. Recently, a tritium-loaded titanium target has become available at TRIUMF, and several experiments employing the target have been planned and approved. For the analysis and planning of future experiments, an evaluation of the target thickness is beneficial. Therefore, we performed measurements of elastic scattering at the ISAC-II facility, TRIUMF. The number of tritons in the target and the degree of hydrogen contamination were deduced from the data. In this talk, the final result of the characterization of the target will be presented. |
Thursday, October 25, 2018 9:00PM - 9:15PM |
EH.00009: Development of the gaseous Xe scintillation detector for the particle identification of high intensity and heavy RI beams Tomoya Harada For the experiments of unstable nuclei, the cocktail RI beams produced by the fragmentation of HI beams are often used. It is necessary to identify the RI beam event by event.RIBF can provide the high intense RI beam, but we cannot fully utilize it due to the radiation damages of the existing detectors for the particle identification. To get enough data efficiently in a limited time, we need new detectors which have a good radiation hardness, a fast timing response, and a good energy and timing resolution. For this purpose, we have developed a new detector employing the scintillation of the gaseous Xe. Since Xe gas is known to have a small work function, a high energy resolution is expected. However, the scintillation properties of the gaseous Xe from high-energy and –intensity HI particles not fully understood so far. In order to evaluate the performance of the gaseous Xe scintillation detector, we tested it with a primary beam of 136Xe 200Mev/u and a secondary beam of A/Z ~2.28 at 300MeV/u produced by 132Xe 400MeV/u at Heavy Ion Medical Accelerator in Chiba from Nov. 2017 to Feb. 2018. I will report the result of this experiment in this conference. |
Thursday, October 25, 2018 9:15PM - 9:30PM |
EH.00010: Understanding Ionization Efficiency from Sub-keV Nuclear Recoil Events in Direct Detection Dark Matter Experiments. Mitchell Matheny Direct detection dark matter experiments are increasingly interested in the low-mass dark matter parameter space. But sensitivity to low mass demands lower thresholds, and with thresholds as low as 54eVee for CDMSlite, there are few and sometimes no nearby measurements of the ionization efficiency of nuclear recoils. The dark matter community widely describes the ionization efficiency from a nuclear recoil with the Lindhard model, but experimental disagreements below 1 keVnr suggest that some of its assumptions, such as treating the atomic binding energy as negligible, may break down. This uncertainty in model predictions and detector response introduces significant error into a low mass parameter space as we do not know if there is a minimum energy required to produce an electron-hole pair from a nuclear recoil. To further understand the minimum recoil energy required to create an e/h pair, more data below 1keVnr is needed. Here, I discuss potential experiments to study low-energy nuclear recoil. In particular I look at the sensitivity of detectors with single e/h resolution in order to verify a modified Lindhard model and to test for directional dependence of the detector response. |
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