Characterization of Silicon-Photomultipliers for a Cosmic Muon Veto detector

A Cosmic Muon Veto (CMV) detector using extruded scintillators is being designed around the mini-Iron Calorimeter detector at the transit campus of the India-based Neutrino Observatory, Madurai for measuring its efficiency at shallow depth underground experiments. The scintillation signal is transmitted through a Wavelength Shifting (WLS) fibre and readout by Hamamatsu Silicon-Photomultipliers (SiPMs). A Light Emitting Diode (LED) system is included on the front-end readout for in-situ calibration of the gain of each SiPM. A characterization system was developed for the measurement of gain and choice of the overvoltage (V ov) of SiPMs using the LED as well as a cosmic muon telescope. The V ov is obtained by studying the noise rate, the gain of the SiPM, and the muon detection efficiency. In case of any malfunction of the LED system during the operation, the SiPM can also be calibrated with the noise data as well as using radioactive sources. This paper describes the basic characteristics of the SiPM and the comparison of the calibration results using all three methods, as well as the V ov of the SiPMs and muon selection criteria for the veto detector.

In situ calibration of two FDR gauges under saline soil conditions in the hyperarid of Chile

A calibration method was developed for two FDR sensors (GS3 and POGO) in saline soil conditions with predominantly fine textures and electrical conductivities that fluctuate between 4.4 and 16.5 dS.m-1. The methodology included the use of infiltration trenches and the recording of the variation of the water content (Ɵ) over time. The results showed that there is an overestimation of Ɵ as a function of the salt content. The standard error obtained with the manufacturer's calibration was 0.09 and 0.19 cm3.cm-3 for GS3 and POGO, respectively. After calibration, the standard error decreased to 0.04 and 0.05 cm3.cm-3, respectively. The R2 of the calibration equations for GS3 and POGO were 0.94 and 0.86 respectively, not being necessary a differentiated calibration by salinity ranges. The GS3 sensor performed better than the POGO in the salinity conditions encountered.