Measurement of Anti-Matter Reaction in LArTPC using Accelerator Beam for GRAMS Experiment
Hinako Taniguchi(Waseda University)ü Phase-1: Verification of antideuteron rate
• June 2023 Implementation• Particle identification:
dE/dX + ToF• Observation of(anti-)deuteron stop events
by Waseda Range Counter

Waseda Range CounterØ Anti-particle Flux

Positron/Anti-Proton Flux:
Well known by other experiments
Anti-Deuteron Flux:
Not yet observed
Secondary-induced fluxes are suppressedon the order of 102 at the low energy side

ü Phase-2: Validation of anti-particle identification methods by LArTPC+TOF• Proposal 2024 January• Observation ofantiparticle reaction• LArTPC:
particle tracking + calorimeter• ToF : Measure Velocity 𝛽

LArTPC+ToF

If observed at low energy side,indirectly suggest DM!

GRAMS target

Detection principle
Phase-1 Beam TimeLine
2023 6/19-21
Deuteron Trigger Events• Two-layer TOFs ⇒ β measurement• LArTPC = tracking calorimeter
Electron signal: Anode pad ⇒ Two-dimensional position information
Optical signal: PMT/SiPM ⇒ Drift time acquisition• shot beam
Trigger/Gate timing check• Reproducibility of K- beam
• Positive beam tune
Kaon+, Proton, Deuteron

J-PARC(Japan Proton Accelerator Research Complex)

K1.8
K1.8BR
K1.1BR

KLK1.1• Anti Proton tune& Rate study(12min.)Cluster ToF[ns]Anti deuteron

Cluster ToF[ns]We could not observe sufficient anti deueteron flux
to make a proposal using anti deuteron beam for Phase 2.

Toward Phase-2• To be proposed to J-PARC with Anti proton only
• Implemented in Geant4 Simulation
Ø Consideration of Incident Momentum• Reflects Phase-1 beam profile dataSetup• LArTPC setupCryostat, GAr, LAr and LArTPC• Front Detectors:
TOFs, Drift chamber and Aerogel Cherenkov
0.8GeV/c(Top view)

For 0.7 GeV/c beam,Anti proton stops around the center of LArTPC.

• Anti deuteron hunt (120min.)1. Phase-1 ResultPion

Ø Expected Signal at LArTPC• Secondary particles:
Some pions
and electron-positrons etc

Data

Simulation

dE[MeV]dE[MeV]

Hadron Experimental Facility

Cluster ToF[ns]Deuteron(15min. each)Ø Positive Particle
Response onRange counter(8-layer)• Pion, Kaon, Proton:
Passed by MIP
Ø Primary proton beam is irradiated to • Deuteron:a fixed target and secondary particles
Stopped at layer 4
are transported
Roughly consistentØ Five beamline configurations
with Simulation!
• K1.8BR beamline:
kaon-, anti proton: Well observed
anti deuteron: Not well observed
Maximum momentum 1.1 GeV/c
Ideal momentum for GRAMS!

Ø High Intensity Proton Beam Facility
Ø Tokai-mura, Ibaraki, JapanØ Three Accelerators
Ø Three Experimental Facilities

Anti deuteron

Captured point distribution
0.7GeV/c
0.6GeV/cdE[MeV]Ø Mass identification:
At the same velocity 𝛃, the dE/dX and track length vary with mass
Ø Charge identification:
Antiparticles are nucleus-captured and emit hadrons (mainly 𝝅)

Deuteron

Cluster ToF[ns]lDeuteronLayerLayer
DataSimulation
dE[MeV]Two physical targets
ü Anti matter search (Anti-Proton/Deuteron/Helium)
Indirect dark matter search
ü MeV-γ ray from SNR/BH/neutron star/Galaxy Center observation
Elucidation of heavy element synthesis process
Indirect dark matter searchØ Deuteron/Anti deuteron Particle
Background elimination
by energy, drift chamber and trigger (TOF) matching.
After CutBefore Cut
Cluster TOT[arbitrary]

Strategy: Two steps

Purpose: Validation of anti-particle identification methods

Cluster TOT[arbitrary]

Observation experiment of cosmic ray antiparticles
and MeV-γ rays using balloon-borne LArTPC @ 40 km above Antarctica

2. Phase-1 Result

Cluster TOT[arbitrary]

Beam Test @K1.8BR Beamline, J-PARC

Cluster TOT[arbitrary]

GRAMS (Gamma-Ray and AntiMatter survey)

LayerLayer

Summary and Future Prospects

・The GRAMS experiment is a balloon/satellite experimentutilizing a LArTPC with one of its goals to indirectly searchfor dark matter.
・Verification of the antiparticle identification method in stages ofPhase-1 and Phase-2 at the J-PARC experimental facility.
・In Phase-1, a sufficient amount of anti deuteron flux was notobtained. In Phase-2, only anti protons will be studied.
・Advancing Simulation, TPC R&D and Electronics readouts for Phase-2.