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

TL;DR

This paper evaluates the radiation hardness of various transistor technologies for upgrading the ATLAS Hadronic Endcap Calorimeter's cold readout electronics in anticipation of the HL-LHC's increased luminosity.

Contribution

It presents experimental results on the radiation tolerance of SiGe bipolar, Si CMOS FET, and GaAs FET transistors under neutron and proton irradiation.

Findings

SiGe bipolar transistors show high radiation tolerance.

GaAs FETs exhibit significant parameter degradation after irradiation.

Proton and neutron irradiation effects differ among transistor types.

Abstract

The expected increase of total integrated luminosity by a factor of 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 Endcap 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 \cdot 10^{16} n/cm2 and with 200 MeV protons up to an integrated fluence of 2.6 \cdot 10^{14} p/cm2. Comparisons of transistor parameters such as the gain for both types of irradiations are presented.