Large-scale detector testing for the GAPS Si(Li) Tracker

TL;DR

This paper reports on the large-scale testing and characterization of over 1100 Si(Li) detectors for the GAPS experiment, demonstrating their low-noise performance and suitability for large-area, cost-effective astrophysics and nuclear physics applications.

Contribution

It presents the first comprehensive characterization of a large batch of GAPS Si(Li) detectors, confirming their performance and feasibility for future large-scale experiments.

Findings

Consistent low-noise performance across over 1100 detectors

Feasibility of large-area, low-cost Si(Li) detector arrays

Detectors meet energy resolution requirements below 4 keV FWHM

Abstract

Lithium-drifted silicon [Si(Li)] has been used for decades as an ionizing radiation detector in nuclear, particle, and astrophysical experiments, though such detectors have frequently been limited to small sizes (few cm$^2$) and cryogenic operating temperatures. The 10-cm-diameter Si(Li) detectors developed for the General Antiparticle Spectrometer (GAPS) balloon-borne dark matter experiment are novel particularly for their requirements of low cost, large sensitive area (~10 m$^2$ for the full 1440-detector array), high temperatures (near -40$\,^\circ$C), and energy resolution below 4 keV FWHM for 20--100-keV x-rays. Previous works have discussed the manufacturing, passivation, and small-scale testing of prototype GAPS Si(Li) detectors. Here we show for the first time the results from detailed characterization of over 1100 flight detectors, illustrating the consistent intrinsic low-noise performance of a large sample of GAPS detectors. This work demonstrates the feasibility of large-area and low-cost Si(Li) detector arrays for next-generation astrophysics and nuclear physics applications.