The radiation induced attenuation of optical fibres below −20°C exposed to lifetime HL-LHC doses at a dose rate of 700 Gy(Si)/hr

Abstract

The radiation induced attenuation of optical fibres below −20°C exposed to lifetime HL-LHC doses at a dose rate of 700 Gy(Si)/hrTo cite this article: D Hall et al 2012 JINST 7 C01047 View the article online for updates and enhancements. Related contentThe radiation hardness of specific multimode and single-mode optical fibres at -25°C beyond a full SLHC dose to a dose of 500 kGy(Si) B T Huffman, C Issever, N C Ryder et al. -The radiation tolerance of MTP and LC optical fibre connectors to 500 kGy(Si) of gamma radiation D C Hall, P Hamilton, B T Huffman et al. ABSTRACT: The LHC luminosity upgrade, known as the HL-LHC, will require high-speed optical links to read out data from the detectors. Such links must be capable of withstanding high doses whilst being kept at low temperatures. Two single-mode and two multi-mode fibres were exposed to 200 kGy(Si) at a dose rate of about 700 Gy(Si)/hr, whilst being kept at about -25 • C. The radiation induced attenuation of these fibres was measured as the fibres accumulated dose. A conservative estimate has been made of the total attenuation expected for a realistic fibre route through the ATLAS detector after a lifetime dose at the HL-LHC. With safety factors, the maximum dose extrapolated to was 375 kGy(Si). All four fibres performed extremely well and were qualified for use at HL-LHC detectors.

The radiation tolerance of MTP and LC optical fibre connectors to 500 kGy(Si) of gamma radiation

“…The radiation tolerance of MTP ribbon fibre connectors and LC single fibre connectors has been tested up to 500 kGy(Si) of γ radiation. A dose of 500 kGy(Si) is a factor of two higher than the lifetime dose expected within an inner tracker detector at the HL-LHC [2]. Neither type of connector exhibited evidence for any significant radiation damage.…”

“…Consequently, electronics within HL-LHC detectors will be exposed to higher doses. For example, by simply scaling simulated ATLAS radiation flux maps [1], the expected lifetime HL-LHC dose at a radius of 30 cm from the beampipe is found to be about 250 kGy(Si) [2]. Upgrade designs of inner detectors minimise cost and material by utilising a high-speed (5-10 Gb/s) optical readout system, which must be capable of operating within the harsh radiation environment present at the HL-LHC.…”

A review of advances in pixel detectors for experiments with high rate and radiation

“…There are three reasons why optical conversion is located some distance away from pixel modules: radiation, geometry, and reliability. Fibers and active optical elements both suffer radiation damage [135,136] and are not currently suitable for environments exceeding 100 Mrad. For the laser drivers, but not the fibers, there have been promising developments in silicon photonic systems using Mach-Zehnder interferometers rather than switching lasers, following the trend in commercial high speed optical links [137].…”

Fibre Optics Cabling Design for LHC Detectors Upgrade Using Variable Radiation Induced Attenuation Model

“…A critical design parameter of the link is to minimize the aggregated Radiation Induced Attenuation (RIA) which is a function of accumulated dose, irradiation dose-rate, fibre temperature and transmitted power over the fibre [3]. Figure 2 shows the simulated radiation map inside the ATLAS and CMS detector cross-section over a 10-year interval [4].…”