[en] Silicon Photo-Multipliers (SiPMs) are semiconductor-based photo-detectors with performances similar to the traditional Photo-Multiplier Tubes (PMTs). An increasing number of experiments dedicated to particle detection in colliders, accelerators, astrophysics, neutrino and rare-event physics involving scintillators are using SiPMs as photodetectors. They are gradually substituting PMTs in many applications, especially where low voltages are required and high magnetic field is present. Hamamatsu Photonics K.K., one of leading producers of photo-detectors, in the last year introduced the S14160 series of SiPMs with improved performances. In this work, a characterization of these devices will be presented in terms of breakdown voltages, pulse shape, dark current and gain. Particular attention has been dedicated to the analysis of the parameters as function of temperature.

[en] Large volume Liquid Argon Time Projection Chambers (LAr-TPC) are used and proposed for neutrino physics and rare event search. Most of these detectors make use of the scintillation light of liquid argon for trigger purposes. Two different approaches can be adopted to provide these detectors with an effective trigger system, relying upon analog or digital processing of signal coming from photodetectors, like photomultiplier tubes or silicon photomultipliers. Each method presents advantages and drawbacks, so the implementation of a hybrid solution can benefit from both approaches. To this purpose, an innovative electronic board prototype has been designed and proposed for the use in large volume LAr-TPC detectors.

[en] The calibration and monitoring system constructed for the HARP experiment scintillator-based time of flight system is described. It is based on a Nd-Yag laser with passive Q-switch and active/passive mode-locking, with a custom made laser light injection system based on a bundle of IR monomode optical fibers. A novel ultrafast InGaAs MSM photodiode, with 30 ps risetime, has been used for the laser pulse timing. The first results from the 2001-2002 data taking are presented, showing that drifts in timing down to about 70 ps can be traced

[en] The MEG II Timing Counter will measure the positron time of arrival with a resolution of 30 ps relying on two arrays of scintillator pixels read out by 6144 Silicon Photomultipliers (SiPMs) from AdvanSiD. They must be characterized, measuring their breakdown voltage, to assure that the gains of the SiPMs of each pixel are as uniform as possible, to maximize the pixel resolution. To do this an automatic test system that can measure sequentially the parameters of 32 devices has been developed.

[en] In the last 30 years, the incredible experimental progress made in the studies of neutrino oscillation allowed to better understand the pattern of neutrino masses and neutrinos mixing. However, further investigation are necessary, in particular concerning a series of experimental anomalies, observed in different neutrino experiments, which are uncorrelated with each other but all hinting at oscillation phenomena. The goal of the new Short Baseline Neutrino program is to perform sensitive searches for ν_e appearance and ν_μ disappearance in the Booster Neutrino Beam in order to understand experimental anomalies in neutrino physics and to perform the most sensitive search for sterile neutrinos at the eV mass-scale. The experiment includes three Liquid Argon Time Projection Chamber detectors located along the Booster Neutrino Beam line at Fermilab. In this paper, the functioning of the Short Baseline Neutrino far detector, ICARUS-T600, is shown. In particular, this work is focused on the detector light collection system and on its upgrade concerning the wavelength shifting of the liquid argon scintillation from vacuum ultra-violet into visible light. (paper)

[en] Silicon Photo-Multipliers (SiPMs) are now widely used as light detectors for several high energy physics experiments. The performance of these devices for the detection of scintillation light of liquefied noble gases, such as Liquid Xenon (LXe) or Liquid Argon (LAr), that emit photons in the Vacuum Ultra-Violet region (VUV, $\lambda =100÷200$ nm) will be presented. In particular, SiPM arrays produced by Hamamatsu, SensL and AdvanSiD have been tested in terms of quantum efficiency using a VUV measurement system based on a monochromator, a deuterium lamp and a NIST calibrated photodiode. A comparison between standard (plastic window) and completely naked devices has been carried out on the wavelength range of $\lambda =120÷170$ nm. Sensitivity in detecting VUV light of tested devices is comparable to standard bialkali PMTs covered with wavelength shifter.

[en] Liquid argon detectors are an interesting option for neutrino experiments. The high density of liquid argon allows using it directly as target for neutrino interactions. The relatively large abundance of argon in the atmosphere makes it a cost-effective medium, allowing the construction of detectors of several hundred tons, such as ICARUS, and even several kton detectors are foreseen for the next generation of experiments, such as DUNE . Besides being suitable to act as the target, liquid argon also serves as the detection medium for the charged particles coming out of the interaction vertex. The interaction time, t${}_0$, can be determined by detecting the photons which are produced together with the electrons in the ionization process. To detect them, the integration of an efficient photon detection system into the liquid argon detector is necessary. One difficulty here is related to the fact that the emitted photons have a wavelength in the VUV range (128 nm). The classical approach for the photon detection system is, therefore, the usage of photomultiplier tubes coated with tetraphenyl-butadiene which shifts the VUV photons to about 430 nm, a wavelength to which the photomultiplier tubes are directly sensitive to. While the basic concept is well established and has been used in several experiments such as ICARUS, ArDM and DarkSide, some aspects of the coating are not well understood such as the preparation of the photomultiplier tube surface which can be either polished or sandblasted. To better understand the effect on the overall photon detection efficiency on one hand and the tetraphenyl-butadiene stability during the cooling down, on the other hand, the quantum efficiencies of sandblasted and polished photomultiplier tubes, coated following the same procedure, were measured with a setup at the Istituto Nazionale di Fisica Nucleare (INFN), in Pavia. In addition, the immersion of the photomultiplier tubes with different soak timings was tested, showing a significantly different behavior for fast and slow immersion for the polished photomultiplier tubes.

[en] Radiation hardness is an important requirement for solid state readout devices operating in high radiation environments common in particle physics experiments. The MEG II experiment, at PSI, Switzerland, investigates the forbidden decay μ⁺ → e⁺ γ. Exploiting the most intense muon beam of the world. A significant flux of non-thermal neutrons (kinetic energy E _{k ≥} 0.5 MeV) is present in the experimental hall produced along the beam-line and in the hall itself. We present the effects of neutron fluxes comparable to the MEG II expected doses on several Silicon Photomultiplier (SiPMs). The tested models are: AdvanSiD ASD-NUV3S-P50 (used in MEG II experiment), AdvanSiD ASD-NUV3S-P40, AdvanSiD ASD-RGB3S-P40, Hamamatsu and Excelitas C30742-33-050-X. The neutron source is the thermal Sub-critical Multiplication complex (SM1) moderated with water, located at the University of Pavia (Italy). We report the change of SiPMs most important electric parameters: dark current, dark pulse frequency, gain, direct bias resistance, as a function of the integrated neutron fluency.

[en] The high intensity pulsed muon beam of ISIS facility at Rutherford Appleton Laboratory (RAL, U.K.) allows to perform high precision muonic X-ray spectroscopy experiments. In particular, FAMU and CHNET_TANDEM projects at RAL are dedicated, respectively, to a precise measurement of the Zemach radius of the proton through the measure of the hyperfine splitting of the ground state of the muonic hydrogen atom and to the optimization of analytical methods based on the muonic atom spectroscopy for non-destructive elementary characterization of archaeological samples. Custom electronic boards dedicated to the detector amplification stages have been designed and prototypized to provide fast high resolution for both experiments. The main features and performance of these custom boards are described in details in this work.

[en] Silicon Photo-Multipliers (SiPMs) at cryogenic temperatures are very promising for the realization of scintillation light detectors to be adopted in particle physics experiments dedicated to neutrino and Dark Matter searches. For these reasons, we tested several devices from different manufacturers with particular emphasis to breakdown voltage, dark current and gain changes at different temperatures. The system, based on a cryo-pump with a cold head, permits to scan the temperature from 300 K down to 50 K. A second system, based on a climatic chamber, was also used. We found that all devices can be operated at cryogenic temperatures. Furthermore, the thermal component of the noise decreases at low temperature, thus allowing the use of the device at higher overvoltage.