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 1WFB: Time-projection Chambers for Radioactive Isotope Beams II |
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Chair: Daisuke Suzuki, RIKEN Nishina Center Room: Hilton King's 2 |
Tuesday, October 23, 2018 11:00AM - 11:30AM |
1WFB.00001: CNS Active Target (CAT) for high-intensity heavy-ion beam experiment Invited Speaker: Hiroshi TOKIEDA We developed GEM-based gaseous active targets, CAT-S and CAT-M, aiming at the missing mass spectroscopy in inverse kinematics with high-intensity heavy-ion beams. One of the physics motivation particularly focused is to explore the nuclear incompressibility of asymmetric nuclear matter through the measurements of the isoscalar giant monopole resonance (ISGMR) with high intensity (∼106 Hz) beams of unstable nuclei of A ∼ 100 at an incident energy of ∼100 MeV/u. ISGMR have the forward peak in the center-of-mass angular distribution. For experiments with the unstable nuclei beam, the low energy recoiled particles need to be measured in inverse kinematics, corresponding to the forward angle scattering up to 10 degrees in the center-of-mass frame. A gaseous active target based on a time projection chamber (TPC) enables us to detect such low energy particles and beam particles, simultaneously. The lowest total kinetic energy of recoil particles to be detected by CAT’s is 0.3 MeV. The CAT’s consist of TPC with equilateral triangular readout pads and an array of silicon detectors beside the TPC. Our TPC is operated with low pressure, for instance, 0.4-atm pure deuterium or hydrogen gas. A set of thick GEMs of 0.4-mm thickness or multi-layered thick GEM of 1.2-mm thickness are employed as electron multiplier in CAT-S and CAT-M, respectively. For the operation under high intensity beams, both type of GEMs have segmented electrodes and the gain of the beam region is typically set about 10 times lower than that of the recoil region. The active area of the CAT-S and CAT-M are about 100 × 100 mm2 and 280 × 310 mm2, respectively. In this talk, the detail of CAT’s and their performances will be presented. |
Tuesday, October 23, 2018 11:30AM - 12:00PM |
1WFB.00002: SπRIT-TPC experiment with neutron rich Sn + Sn collisions in RIKEN-RIBF Invited Speaker: Mizuki Kurata-Nishimura Investigation of nuclear Equation of State (EoS) is one of the most attractive topics not only for nuclear physics but also astrophysics since the neutron star merger was discovered with the gravitational wave. Nuclear EoS indicates large uncertainly in theory, because of lack of information above the normal nuclear density. Neutron rich heavy ion collisions are suitable to investigate isospin symmetry dependence of nuclear EoS at supra-saturation. The first experiment using SAMURAI Pion-Reconstruction and Ion-Tracker-Time-Projection Chamber (SπRIT-TPC) was performed at RIKEN-RIBF-SAMURAI in 2016. The nuclear collisions with 132Sn and 108Sn beams at 270MeV/u on 124Sn and 112Sn targets were utilized for the systematic study. To trigger central collision events effectively, a multiplicity trigger, a large fragment beam veto and an active beam collimator systems were employed. And fast trigger worked to brock unnecessary electron through a gating-grid-driver. Tracking software has been developed based on FairROOT framework and analysis is on going. In this talk, the properties of SπRIT-TPC and the recent results of obtained by day-one experiment will be shown and discussed. |
Tuesday, October 23, 2018 12:00PM - 12:30PM |
1WFB.00003: The SOLARIS spectrometer Invited Speaker: Alan Wuosmaa SOLARIS is a dual-mode spectrometer designed for the study of a wide range of transfer and inelastic-scattering reactions at incident beam energies around the Coulomb barrier, to be delivered by the reaccelerated (ReA) beam facility at the National Superconducting Cyclotron Laboratory (NSCL), and in due course the Facility for Rare Isotope Beams. The spectrometer will operate like the HELIOS spectrometer at Argonne National Laboratory, with an on-axis Si array, primarily for studies with beam intensities greater than 5,000 particles per second. It will also be capable of operating with the NSCL Active Target Time Projection Chamber inside the bore of the solenoid, taking advantage of the up to 4-T field. In this latter mode of operation, reactions with beams as weak as a few hundred particles per second are possible. An overview of SOLARIS, the planned implementation of SOLARIS on the ReA6 beamline, and physics opportunities will be presented. |
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