Optical fibres

For my ATLAS service work, I worked on the Versatile Link project. This is a joint effort between members of CERN, Fermilab, Oxford University and Southern Methodist University to develop a high-speed optical link to be used in the LHC upgrade program, the High Luminosity LHC.

The parts of the link that I worked on were the optical fibres themselves and the fibre connectors. These components are damaged by radiation, so we must find candidates that are capable of operating up to doses received at the HL-LHC. I performed this research under the supervision of Todd Huffman and Tony Weidberg.

Fibre testing

When optical fibres are irradiated they discolour, causing the signal to be attenuated. At the low temperatures (-25°C) needed by particle physics detectors, this effect is even worse than usual. We developed a liquid CO2 cooling system, which we took to a nuclear reactor in Belgium. By measuring the strength of a laser signal through the fibre as it was exposed to radiation, we were able to find which candidate fibres are suitable for use at HL-LHC detectors.

I presented the results of this experiment to the Topical Workshop on Electronics for Particle Physics, a major international conference in Vienna. The talk can be viewed here. I also wrote a journal article which can be found here.

Connector testing

In order to gauge how MTP and LC connectors are damaged by radiation, we irradiated them with cobalt-60 sources in Taiwan. We performed device-under-test experiments before and after the irradiation and considered the difference in insertion loss between the two tests. I wrote a journal article describing the experiment, which can be found here.