Test and Simulation of Plastic Scintillator Strips readout by Silicon Photomultipliers Tosi Nicolò, Balbi G., Boldini M., Cafaro V., Dallavalle G.M., D Antone I., Fabbri F., Giordano V., Lax I., Montanari A., Navarria F.L., Rovelli T., Torromeo G., Travaglini R. INFN & Univ. Bologna October 9th, 2013 Tosi Nicolò (INFN & Univ. Bologna) Scintillation detector with SiPM readout October 9th, 2013 1 / 10
Introduction Scintillation detector developed for the Muon system of the SuperB experiment (IFR). Based on plastic scintillator strips, WaveLength Shifting fibers and Silicon Photomultipliers. Several configurations were tested to improve on light collection. Identified a viable solution producing a large S/N ratio for a low complexity and cost. We also developed a detailed FLUKA simulation that correctly reproduces experimental data. Tosi Nicolò (INFN & Univ. Bologna) Scintillation detector with SiPM readout October 9th, 2013 2 / 10
Custom DAQ Electronics This system provides all necessary services for controlling and acquiring data from a SiPM based detector with up to 8 channels: programmable bias voltage generation signal amplification and shaping threshold based discrimination charge integration and digitization pulse generator for LED calibration fully programmable trigger logic bias and temperature monitoring The system communicates with the DAQ PC using UDP over a gigabit ethernet link. Tosi Nicolo (INFN & Univ. Bologna) Scintillation detector with SiPM readout October 9th, 2013 3 / 10
Basic Detector Element Extruded plastic scintillator strip, 10 mm thick, 45 mm wide Co-extruded TiO 2 coating WaveLength Shifting fiber (Kuraray Y11-300-M, ø1mm) Silicon Photomultiplier (Hamamatsu 1 mm 2, 50 µm pixels) The simulation model reproduces generation and propagation of scintillation light, including wavelength-dependent behavior. Tosi Nicolò (INFN & Univ. Bologna) Scintillation detector with SiPM readout October 9th, 2013 4 / 10
Improving light collection Optical Glue Substantially increased light collection efficiency. Increased uniformity for different groove quality. Adhesive aluminum tape Reflects lights escaping from gaps in TiO 2 coating. Reflects light propagating in the wrong direction along the fiber. Tosi Nicolò (INFN & Univ. Bologna) Scintillation detector with SiPM readout October 9th, 2013 5 / 10
Improving light collection Data (cosmics) Base Configuration 27 ± 2 pixels/mip Optical Glue only 35 ± 3 pixels/mip +30% Optical Glue and aluminum tape 46 ± 3 pixels/mip +70% Simulation Base Configuration 29 pixels/mip Optical Glue only 34 pixels/mip +20% Optical Glue and aluminum tape 48 pixels/mip +70% Tosi Nicolò (INFN & Univ. Bologna) Scintillation detector with SiPM readout October 9th, 2013 6 / 10
More fibers To further increase light collection, we tested two prototypes with a second fiber: Two fibers in separate grooves. Two fibers in the same groove. We found that the total signal increases 70% w.r.t. a single fiber, independent of fiber placement. By contrast, noise increases with sensitive SiPM area, but falls off exponentially. The relative increase predicted by simulation is in excellent agreement with our measurement. We can rely on simulation for the study of other geometries (3 fibers,... ). Tosi Nicolò (INFN & Univ. Bologna) Scintillation detector with SiPM readout October 9th, 2013 7 / 10
Attenuation We studied attenuation for scintillator strips up to 2 m long. The signal from the far end is reduced by less than 50%. Simulation uses independently measured attenuation lengths for scintillator and WLS fiber, obtaining a good agreement with real data. Tosi Nicolò (INFN & Univ. Bologna) Scintillation detector with SiPM readout October 9th, 2013 8 / 10
Conclusions Our prototype detector maximizes signal to noise ratio while maintaining a low cost and complexity. The solution is quite versatile and can be effectively employed in large area detectors. Our simulation is capable of predicting the impact of modifications on the original design and can be used to test many more configurations. Tosi Nicolò (INFN & Univ. Bologna) Scintillation detector with SiPM readout October 9th, 2013 9 / 10
Backup LED Calibration Tosi Nicolò (INFN & Univ. Bologna) Scintillation detector with SiPM readout October 9th, 2013 10 / 10