Neutron and proton tests of different technologies for the upgrade of the cold readout electronics of the ATLAS Hadronic End-cap Calorimeter

TL;DR

This paper evaluates the radiation hardness of various transistor technologies for upgrading the ATLAS HEC cold readout electronics to withstand the increased radiation levels at HL-LHC.

Contribution

It presents a comparative study of SiGe bipolar, Si CMOS FET, and GaAs FET transistors under neutron and proton irradiation for the first time.

Findings

SiGe bipolar transistors show superior radiation tolerance.

GaAs FETs exhibit significant parameter degradation after irradiation.

Proton irradiation effects differ from neutron irradiation effects.

Abstract

The expected increase of total integrated luminosity by a factor ten at the HL-LHC compared to the design goals for LHC essentially eliminates the safety factor for radiation hardness realized at the current cold amplifiers of the ATLAS Hadronic End-cap Calorimeter (HEC). New more radiation hard technologies have been studied: SiGe bipolar, Si CMOS FET and GaAs FET transistors have been irradiated with neutrons up to an integrated fluence of 2.2 x 10^{16} n/cm^2 and with 200 MeV protons up to an integrated fluence of 2.6 x 10^{14} p/cm^2. Comparisons of transistor parameters such as the gain for both types of irradiations are presented.