The outermost detector subsystem at a collider experiment is usually the muon system. Relying on the property of energetic muons to penetrate much more material than most other particles emerging from high energy collisions, as well as to leave distinct ionisation trace in the detectors, the muon system identifies this particle type with high efficiency. Depending on the specifics of the experiment, the muon momenta are measured either by matching identified muon tracks to the corresponding tracks in the main tracker, or directly from the tracks in the muon system.

Muon system sensors are typically embedded in the field-return iron yoke of the detector magnet, difficult to reach for maintenance. A solution for the sensors that allows long term reliable and economic operation, while limiting the number of readout channels to a reasonable level is to use scintillator strips read out with Silicon Photomultipliers (SiPM) using wavelength shifting fibers (WLS) to collect and focus light on the small surface of the SiPM. An important figure of merit for such configurations is the achievable resolution of position along the strip measured using the time difference of the arrival of the light signal to the two ends of the strip. We investigate the scintillator option for the muon system for future colliders in collaboration with the Particle Physics Initiatives group at Fermilab, USA.

Time and position resolution of the scintillator strips for a muon system at future colliders

 

 

Various designs of scintillator strips with WLS fibers and SiPM readout for the muon system were tested for time and position resolution in the muon beam of the Fermilab Test Beam Facility.

The state of the art low-noise SiPM from Hamamatsu features excellent photon-number resolution and triggering at the single-photon level. There are two recent publications related to this study NIM A848 and NIM A832 .