The radiation hardness of specific multi-mode and single-mode optical fibres at -25°C beyond a full SLHC dose to a dose of 500 kGy(Si)

Abstract

The optical fibres that will be used in SLHC detectors will be exposed to high doses and low temperatures in the inner detectors. A number of Single-Mode (SM) and Multi-Mode (MM) fibres have been tested for radiation hardness by exposure beyond a full SLHC dose to 500 kGy(Si) in the -25°C operating temperatures expected in the upgraded inner detectors. From these measurements conservative estimates of the level of Radiation Induced Absorption (RIA) have been calculated for these fibres in realistic paths through an upgraded inner detector. Two SM fibres have been found whose total calculated RIAs were much lower than the budgeted 1 dB, despite the high dose rates used in the experiment. The RIAs for the DrakaElite Super RadHard Single-Mode Fiber and Fibre X were calculated to be 0.142 and 0.064 dB respectively. Another SM and a MM fibre showed high levels of RIA during the experiment, however they cannot be ruled out as candidate fibres due the the high dose rate of 27 kGy(Si)/hr used.