A Scintillator Based Muon System with SiPM Readout for the SuperB Detector

The existing muon detectors for high-energy physics experiments are mainly made of gas chambers such as Resistive Plate Chambers, Limited Streamer Tubes or Multi Wire Proportional Chambers. With the increasing luminosity of the new accelerators and the increment in dimensions of the experiments the development of a new detection technique, which is robust, cheap and capable to sustain high particle rate, is mandatory. We present the technology proposed for the Super B muon system. The detector is based on MINOS style extruded scintillators coupled to wavelength shifting fibers. The light readout is done by means of Silicon Photomultiplier devices. We report the R&D results on prototypes that can be operated either with binary readout, measuring only one coordinate, or with a TDC readout that can measure both the coordinate at the same time with adequate precision. Efficiency and time resolution will be discussed for different prototype geometry as well as the main operational issues related to the photodetectors, like stability, noise rate and neutron damage. A full-scale prototype with the same geometry designed for the SuperB experiment is under construction in our lab and it will be tested with a muon/pion beam at FNAL next fall. The structure optimization has been studied using a GEANT4 Monte Carlo simulation and the expected muon identification performances have been evaluated with a neural network algorithm, we present preliminary results of the optimization and its implication for the SuperB muon system.