Measured gain suppression in FBK LGADs with different active thicknesses

TL;DR

This study investigates how different thickness LGADs respond to high-energy proton deposits, revealing gain suppression effects relevant for particle detection and identification.

Contribution

It provides experimental data on gain suppression in LGADs of various thicknesses under MeV proton irradiation, advancing understanding of their behavior in high-energy physics applications.

Findings

Gain suppression varies with LGAD thickness.

Device response depends on bias voltage and proton energy.

Thicker LGADs show different gain characteristics.

Abstract

In recent years, the gain suppression mechanism has been studied for large localized charge deposits in Low-Gain Avalanche Detectors (LGADs). LGADs are a thin silicon detector with a highly doped gain layer that provides moderate internal signal amplification. Using the CENPA Tandem accelerator at the University of Washington, the response of LGADs with different thicknesses to MeV-range energy deposits from a proton beam were studied. Three LGAD prototypes of 50~$\mu$m, 100~$\mu$m, 150~$\mu$m were characterized. The devices' gain was determined as a function of bias voltage, incidence beam angle, and proton energy. This study was conducted in the scope of the PIONEER experiment, an experiment proposed at the Paul Scherrer Institute to perform high-precision measurements of rare pion decays. LGADs are considered for the active target (ATAR) and energy linearity is an important property for particle ID capabilities.