Performance of the Gamma-ray Transient Monitor at the IHEP Electron-Beam Facility

TL;DR

This paper evaluates the performance of the Gamma-Ray Transient Monitor's detection capabilities and response characteristics using ground-based electron-beam tests and simulations, confirming its readiness for space deployment.

Contribution

It provides a detailed performance assessment of the GTP using electron-beam tests and simulations, validating its design and response for gamma-ray burst detection.

Findings

GTP has a dead time of less than 4 μs for normal signals.

GTP's response to electrons in 0.4-1.4 MeV range is normal.

Simulation and experimental results are consistent.

Abstract

Gamma-Ray Transient Monitor (GTM) is an all-sky monitor onboard the Distant Retrograde Orbit-A (DRO-A) satellite, with the scientific objective of detecting gamma-ray bursts in the energy range of 20 keV to 1 MeV. GTM is equipped with five Gamma-Ray Transient Probes (GTPs), utilizing NaI(Tl) scintillators coupled with silicon photomultiplier (SiPM) arrays for signal readout. To test the performance of the GTP in detecting electrons, we used the IHEP Electron-Beam Facility (a continuous-energy-tunable, low-current, quasi-single-electron accelerator) for ground-based electron tests of the GTP. This paper provides a detailed description of the operating principles of the electron accelerator and presents the process and results of the GTP electron-beam tests. The test results show that the GTP has a dead time of less than 4 $\mu$s for normal signals and approximately 70 $\mu$s for overflow signals, consistent with the design specifications. The time-recording capability of the GTP was tested and found to be normal, with accurate recording of overflow events. The GTP's response to electrons in the 0.4-1.4 MeV range is also normal. Additionally, we used Geant4 to simulate the GTP's energy response and performed a comparative analysis of the simulation and experimental results. The performance tests and ground-based electron calibration validated the design of the GTP and enhanced the GTP's mass model, laying the foundation for payload development, in-orbit observation strategies, and scientific data analysis.