The group has developed a Muon Hodoscope apparatus for the purpose of undergraduate teaching and educational public engagement.

The apparatus comprises a 5 by 5 stack of scintillator bars, each bar having a square cross-section with 5cm side and 25 cm in length.

The scintillation light produced in a bar by the passage of a charged particle is sensed by single-photon-sensitive Silicon Photomultipliers and digitised in a custom electronics chain.

The path of cosmic ray muons (naturally occurring charged particles travelling at speeds close to the speed of light) is therefore revealed by the pattern of light produced as the muon traverses the stack of bars. Some examples are shown below where each yellow square indicates that a flash of light was seen in the scintillator bar at that location. Hover over the image to pause the slideshow.

Threshold scans

The plot below shows the dark count rate as a function of the applied threshold for each sensor overlayed on the same plot. There are two sensors in each of the 25 scintillator bars. The vertical scale is logarithmic so that the variation in rate over many powers of 10 can be seen. The plots display a step-like pattern for each sensor which is characteristic of silicon photomultipliers. The steps occur at threshold intervals equivalent to the amplitude of the signal from a single photon illustrating the exceptional sensitivity of these devices.