The Search for the X17 boson: Analyzing e⁺e^- pair production processes with the prototype AT-TPC using Geant4

In 2016, a group of scientists discovered a possible candidate for a dark fifth-force carrier of the Universe during an experiment in ATOMKI in Debrecen, Hungary. This hypothetical boson would come from an internal pair creation of the decay of 8Be. In particular, scientists had measured the angular correlations of e⁺e^- pairs and observed that at large angles, a neutral particle with a mass of 16.70±0.35(stat)±0.5(syst) MeV/c² and J^π=1⁺ was created, hence the name, X17.

The prototype Active-Target Time-Projection Chamber (pAT-TPC) was used to conduct an experiment at the tandem facility of Notre Dame to search for the X17 resonance via the ⁷Li(p,g)⁸Be reaction. The angular distribution of the produced e⁺e^- pair from the g conversion will be reconstructed to identify the possible existence of this boson. Preliminary analysis of the data indicates a relatively high identification of triple tracks of two electrons and one positron. A realistic Geant4 Monte Carlo simulation was developed to describe the experimental setup, understand the background, and provide information on the efficiency and resolution of the system. In this presentation, I will discuss and present results from this study. This research is part of PING - Physicists Inspiring the Next Generation: Exploring the Nuclear Matter 2023.