Cosmic Ray Tagger - Overview

Cosmic Ray Tagger (CRT) system is utilized by the MicroBooNE experiment to provide precise time and position information of any TPC-external particle interactions accompanying any activity in the experiment’ liquid argon time projection chamber. This system enables the MicroBooNE experiment to efficiently remove cosmogenic-related activity from beam neutrino datasets, as well as allowing precision detector response characterization and calibration utilizing cosmic muons. The MicroBooNE CRT is composed of 4 scintillator planes, constituting the top, underside and side coverage of the detector cryostat. The dimensions of these planes go from 4 m x 9 m to 14 m × 8 m. Each plane is made of several scintillator modules. A total of 73 modules are needed to form the four planes. This module configuration was chosen to provide maximum coverage while adapted to the available space in the LAr Test Facility. This configuration allows 85% of the total crossing muon flux to be tagged by at least two planes. Modules consist of a row of 16 mechanically joined 10.8 cm wide scintillator strips. Scintillation light from the strips is passed to a Silicon Photomultiplier (SiPM) on one strip end through wavelength-shifting fibers Kuraray Y11M along each strip edge. Two SiPMs model S12825-050P by Hamamatsu are used to fully read out one scintillation strip, so 32 photosensors are employed in one single module. Signals from the 32 SiPMs are sent along through cables to a front-end electronics board (FEB) attached to one side of each module. Signal processing is performed in these boards and read out for storage or higher-level triggering.

The full description of the system can be found in MicroBooNE docDB 6563: