Influence of Cosmic Radiation while Testing the Time Reversal Symmetry in the Decay of Ortho-Positronium Atoms using the J-PET detector

J Raj,E Czerwiński

doi:10.1088/1742-6596/1586/1/012010

Abstract

This article reports the influence of cosmic radiation interaction while testing the T-symmetry in metastable triplet states of positronium with the Jagiellonian-Positron Emission Tomograph (J-PET) detector. The J-PET detector developed at Jagiellonian University in Krakow, Poland is one of its kind being based on organic scintillators. J-PET is an axially symmetric and high acceptance scanner that can be used as a multi-purpose detector system. It is well suited to pursue tests of discrete symmetries in decays of positronium in addition to medical imaging. Cosmic rays have been considered as a well known source of background while performing test measurements with the J-PET detector. It is important to estimate and reject the significant contribution of the cosmic ray interactions within the J-PET detector in order to improve the sensitivity while testing T-symmetry violation. Therefore, the results of cosmic radiation uniquely being separated due to their large energy deposits in plastic scintillator detectors are shown in this article.

Highlights

Cosmic rays were discovered by an Austrian physicist Victor Hess in the early 1900’s when he found that a charged electroscope discharged rapidly as it ascended in a balloon [1]
The results presented in this article were produced using the Jagiellonian-Positron Emission Tomograph (J-Positron emission tomography (PET)) analysis framework to collect data and perform off-line analysis [10, 16]
Discrete symmetries were proposed to be tested with the ortho-positronium (o-Ps) system by determining the non-zero expectation value of the operator constructed the polarization ( i) direction and momentum direction (k2) of the annihilation photons originating from the decay of o-Ps atoms, as listed in Table 1 [7]

Summary

Introduction

Cosmic rays were discovered by an Austrian physicist Victor Hess in the early 1900’s when he found that a charged electroscope discharged rapidly as it ascended in a balloon [1]. 3. Producing meta-stable ortho-Positronium to test T-symmetry recorded by the J-PET detector Time reversal symmetry violation has not been observed in purely leptonic systems, so far [21].

Results

Conclusion