研究目的
To explore the feasibility of applying a new method for studying fundamental discrete symmetry violation in a purely leptonic system using the J-PET detector, specifically focusing on time reversal symmetry violation through polarization measurements of annihilation photons from ortho-positronium decay.
研究成果
The J-PET detector is feasible for testing time reversal symmetry violation in ortho-positronium decay by measuring photon polarization. With planned upgrades, it is expected to collect about 10^9 events over three years, improving sensitivity by an order of magnitude compared to previous studies. This approach offers a novel way to explore discrete symmetries in leptonic systems.
研究不足
The requirement for five hits per event reduces the data sample by a factor of about 10^3, limiting the event rate. The method relies on accurate identification of scattered photons and polarization estimation, which may introduce uncertainties. The sensitivity is constrained by the current detector configuration and data collection time.
1：Experimental Design and Method Selection:
The study uses the J-PET detector, an axially symmetric scanner with organic scintillators, to measure momenta and polarization vectors of annihilation photons. The method involves constructing T-odd symmetry operators from polarization and momentum vectors to test time reversal violation.
2：Sample Selection and Data Sources:
A point-like 22Na source is placed in the detector center surrounded by XAD-4 porous polymer to enhance ortho-positronium production. Data are collected from events with five interactions: one de-excitation photon, three annihilation photons, and one scattered photon.
3：List of Experimental Equipment and Materials:
J-PET detector with 192 plastic scintillator strips (EJ-230), Hamamatsu R9800 photomultipliers, trigger-less Data Acquisition System (DAQ), Front-End Electronics (TDCs or ADCs), 22Na source, XAD-4 porous polymer.
4：Experimental Procedures and Operational Workflow:
The source emits positrons that form ortho-positronium, which decays into three photons. Events are selected based on hit multiplicity, time-over-threshold measurements for energy deposition, and kinematic criteria (e.g., sum of azimuthal angles >180°). Polarization is estimated from cross-products of momenta.
5：Data Analysis Methods:
Data are analyzed using the J-PET analysis framework, a ROOT-based software, to reconstruct events, calibrate the system, and compute expectation values of symmetry operators.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
