Speaker
Description
The Gamma-Ray and AntiMatter Survey (GRAMS) is a balloon-borne and satellite-based experiment designed for MeV gamma-ray observations and indirect searches for dark matter via antimatter detection. It uses a cost-effective and scalable Liquid Argon Time Projection Chamber (LArTPC), offering enhanced sensitivity to MeV gamma rays.
In this energy range, Compton scattering is the dominant interaction in argon, so the detector operates as a Compton camera. We are developing a small-scale prototype, NanoGRAMS, to demonstrate this concept. Precise measurement of deposited energy in argon is critical for accurate event reconstruction. Factors such as argon purity, electron-ion recombination, and the electron drift length in argon are known to influence charge pulse height, affecting both energy deposition measurement and event reconstruction. A realistic NanoGRAMS-based simulation that incorporates these effects is therefore essential.
To model these effects, we employed SolidStateDetectors.jl, a simulation framework originally developed for semiconductor detectors. This tool simulates charge induction on the anode from drifting electrons and purity effects. We extended it with a custom model of electron-ion recombination based on Birks formalism and the charge readout response. Combined with ComptonSoft, which is based on Geant4 and serves as the event reconstruction framework, we investigated their impact on the accuracy of event reconstruction.
In this presentation, we will describe our simulation methodology and results, including the influence of charge drift effects on the event reconstruction, and comparisons between different detector configurations (such as purity, bias voltage, pixel/strip size and the use of Frisch grid) to optimize the performance.
