Updated Results of a Solid-State Sensor Irradiation Study for ILC Extreme Forward Calorimetry

TL;DR

This study evaluates the radiation tolerance of silicon and gallium-arsenide sensors under conditions simulating the ILC's extreme forward calorimeter environment, demonstrating their resilience up to 220 MRad doses.

Contribution

It provides new experimental data on the radiation hardness of specific sensor types under high-energy shower conditions relevant for ILC detectors.

Findings

Silicon diodes and GaAs sensors maintained charge collection efficiency up to 220 MRad.

Hadronic radiation effects significantly impact sensor durability in calorimeter environments.

Sensors showed promising radiation tolerance for use in high-radiation collider regions.

Abstract

Detectors proposed for the International Linear Collider (ILC) incorporate a tungsten sampling calorimeter (`BeamCal') intended to reconstruct showers of electrons, positrons and photons that emerge from the interaction point of the collider with angles between 5 and 50 milliradians. For the innermost radius of this calorimeter, radiation doses at shower-max are expected to reach 100 MRad per year, primarily due to minimum-ionizing electrons and positrons that arise in the induced electromagnetic showers of e+e- `beamstrahlung' pairs produced in the ILC beam-beam interaction. However, radiation damage to calorimeter sensors may be dominated by hadrons induced by nuclear interactions of shower photons, which are much more likely to contribute to the non-ionizing energy loss that has been observed to damage sensors exposed to hadronic radiation. We report here on the results of SLAC Experiment T-506, for which several different types of silicon diode and gallium-arsenide sensors were exposed to doses of radiation induced by showering electrons of energy 3.5-10.6 GeV. By embedding the sensor under irradiation within a tungsten radiator, the exposure incorporated hadronic species that would potentially contribute to the degradation of a sensor mounted in a precision sampling calorimeter. Depending on sensor technology, efficient charge collection was observed for doses as large as 220 MRad.