The detection of minimum ionising particles with scintillating fibres using multi-pixel hybrid photodiodes

Recent measurements of the performance of the newly available multi-pixel Hybrid Photodiode (M-HPD) have demonstrated their particular value in the detection of very low light-level signals in the visible region. The single and multiple photo-electron response characteristics of these devices is unmatched by any other room-temperature device. This characteristic, coupled with their speed of response and the availability of an internally-generated trigger signal when one or more of the pixels detect an event, makes them particularly interesting as possible photo-detectors for fast plastic scintillators and, in particular, as detectors for reading out scintillating fibres. The results of tests made when Minimum Ionising Particles (MIPs) pass through single and multi-clad plastic scintillating fibres have confirmed the usefulness of these devices in particle-tracking applications. The technique used to read-out 61 channels of data is described along with a way to view as many as 2000 fibres with just two 61-pixel M-HPDs. Finally, an outline concept for a new high energy gamma-ray telescope is described. This could use multiple planes of scintillation fibres read-out by M-HPDs.