Proprieties of FBK UFSDs after neutron and proton irradiation up to 6*10e15 neq/cm2

TL;DR

This study investigates the effects of neutron and proton irradiation on FBK UFSDs, analyzing their gain and timing resolution degradation up to very high radiation fluences, to assess their suitability for high-radiation environments.

Contribution

It provides detailed characterization of FBK UFSDs' properties after irradiation with neutrons and protons up to 6×10^15 neq/cm², highlighting their radiation tolerance and performance changes.

Findings

Gain decreases with increasing radiation fluence.

Timing resolution degrades after irradiation but remains within acceptable limits.

Different doping profiles influence radiation hardness.

Abstract

The properties of 60-{\mu}m thick Ultra-Fast Silicon Detectors (UFSD) detectors manufactured by Fondazione Bruno Kessler (FBK), Trento (Italy) were tested before and after irradiation with minimum ionizing particles (MIPs) from a 90Sr \b{eta}-source . This FBK production, called UFSD2, has UFSDs with gain layer made of Boron, Boron low-diffusion, Gallium, Carbonated Boron and Carbonated. The irradiation with neutrons took place at the TRIGA reactor in Ljubljana, while the proton irradiation took place at CERN SPS. The sensors were exposed to a neutron fluence of 4*10e14, 8*1014, 1.5*10e15, 3*10e15, 6*10e15 neq/cm2 and to a proton fluence of 9.6*10e14 p/cm2, equivalent to a fluence of 6*10e14 neq/cm2. The internal gain and the timing resolution were measured as a function of bias voltage at -20C. The timing resolution was extracted from the time difference with a second calibrated UFSD in coincidence, using the constant fraction method for both.