First in-flight observation with the novel coincidence readout SiPM-based detectors of DRO/GTM

SiPM-based gamma-ray detector has been increasingly utilized in space telescopes. However, its performance in the space environment would be significantly degraded, especially in the low-energy band, owing to the radiation-induced noise increase of SiPM. To address this problem, we have developed and implemented a novel coincidence readout design for SiPM-based detectors of the Gamma-ray Transient Monitor (GTM) onboard the DRO-A satellite (i.e., DRO/GTM). In this paper, we report the first in-flight observation results of DRO/GTM, focusing on the validation and performance studies of the coincidence readout technology, after a brief introduction of the working mode and data type of coincidence readout. We find that GTM detectors can correctly process and label coincidence events, identify the noise signals of SiPM, and safeguard the detection sensitivity of DRO/GTM especially in the low energy band, which is critically important for scientific observations in multi-messenger astronomy era. Our results not only validate the novel design of the coincident readout of DRO/GTM but also showcase its great advantages in mitigating the problems of SiPM noise. Therefore, this technology provides a very promising solution for future SiPM-based detectors for space exploration.