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Bibliographic Details
Main Authors: Yin, Jilong, Wang, Yi
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2602.08402
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Table of Contents:
  • Accurate reconstruction of the horizontal vertex $(x,y)$ from the S2 electroluminescence pattern is essential for fiducialization and background rejection in dual-phase argon time projection chambers. In this work, we perform a Geant4-based simulation study using the G4DS framework to investigate how detector geometry, in particular the distance between the top photodetector plane and the gas pocket, impacts S2-based XY reconstruction. A compact dual-phase argon TPC instrumented with seven Hamamatsu R8520-506 PMTs is simulated with electron recoils at 41.5 keV (corresponding to the ${}^{83m}\mathrm{Kr}$ calibration energy), as well as 1.0 keV to probe the low-S2 regime. The PMT array height is scanned from 0 mm to 50 mm, and XY positions are reconstructed using a geometrical solid-angle (GSA) method with the S2 emission modeled by 1 mm-thick slices across the 7 mm gas pocket. The results show a clear non-monotonic dependence of reconstruction bias and resolution on PMT height, driven by the trade-off between S2 light sharing and photon statistics. These findings provide guidance for geometry optimization in future low-threshold dual-phase argon detectors and will be validated with upcoming prototype measurements.