The Super MuSR detector system is unlike anything else developed at ISIS. It requires a special type of light sensor – one than can withstand the big magnetic fields that the scientists using the instrument will apply to their samples. These are called silicon-photomultipliers (SiPM) and can measure a single photon to within a billionth of a second.
The SiPMs are coupled to small blocks of scintillator – a special material that emits light when stuck by radiation. Super MuSR requires nearly two thousand SiPMs! As a comparison, the current MuSR instrument has just 64 detectors. Fitting this much detector technology into such a small space has been an exciting challenge for the detector systems team.
In September, the Super MuSR team used the MuSR beamline over a two-week intensive testing period to check the detector system meets specification. The testing involved Andrea Abba and Francesco Caponio from Nuclear Instruments, who have supplied part of the detector and data acquisition system. This made them the first official Super MuSR users on the proposal system!
“We confirmed the electronics were stable, resilient against noise and able to measure muon signals even when in a large magnetic field," explains Dan Pooley, who is leading on the detector development for Super MuSR. “The tests were very successful; demonstrating that the system will work well when we scale up to the full detector barrel next year."
They were also able to successfully test the cooling system, and a novel method for ensuring the system is continuously calibrated.
To get this far has involved staff from across ISIS and Technology, including students on industrial placements, graduates and technicians. The fact that these critical tests were successful means that the detector build can now progress to the next stage.
Some of the team involved in the detector design and development for Super MuSR:
Back line – Alex Jones, Rhea Stewart, Peter Baker, Will Perry, Akanay Avoroglu
Middle line – Zoe Clark, Gabriel Olaofe, Andrea Abba
Front line – Dan Pooley, Francesco Caponio