Speaker
Description
The GRAMS (Gamma-Ray and AntiMatter Survey) program aims to deliver unprecedented sensitivities for astrophysical observations with MeV gamma rays and indirect dark matter searches with antimatter using a search for composite antinuclei (antideuteron and antihelium). GRAMS uses a Liquid Argon Time Projection Chamber (LArTPC) to detect cosmic-ray / gamma-ray events. The capability of the detector was successfully demonstrated in an engineering flight in Japan with a small size TPC (10 cm x 10 cm x 10 cm) detector, and in an antiproton beam test at the J-PARC facility.
We are currently working on an upcoming prototype balloon flight (pGRAMS) planned to fly from Tucson, Arizona, in early 2026. The goal of the prototype flight is to successfully operate a larger TPC (30 cm x 30 cm x 20 cm) fully instrumented with waveform sampling electronics and the time-of-flight (TOF) and multiplicity detector (MPD) systems at the flight altitude, and demonstrate particle-tracking capability for charged particles and event reconstruction techniques for MeV gamma rays including using the MPD as an anticoincidence detector.
The TOF system for pGRAMS consists of two optically-separated layers of plastic scintillators. The upper TOF (UTOF) section will be placed 50 cm above the cryostat, covering a 75 cm x 75 cm area using 24 scintillator paddles (2.7 cm x 75 cm x 1.0 cm), and the middle TOF (MTOF) section will be located just above the cryostat, covering a 50 cm x 50 cm area using 16 scintillator paddles (2.7 cm x 50 cm x 1.0 cm). The TOF spans most of the geometric acceptance of the TPC for particles arriving from the upper hemisphere centered on the TPC top and thus particles detected by the TOF and the TPC can be correlated. Four Hamamatsu 6 mm x 6mm MPPC in series connection will be attached at each end of the scintillator paddles, and the signals from both the TOF and MPD will be read out by a single PETsys TOFPET2 ASIC system.
We will present the current status of the development of the pGRAMS TOF system including results of the recent beam test at J-PARC to show the preliminary performance.
| Collaboration(s) | GRAMS |
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