The MEG II experiment based at PSI (Zuerich, Switzerland) has been committed and is taking data since 2021 to improve sensitivity on the decay mu(+) -> e(+) gamma. The pixelated Timing Counter (pTC), consisting of two arrays of 512 5 mm thick scintillator pixel each, read out by 6 3x3 mm(2), 50 mu m cell, Silicon Photomultipliers (SiPMs) from AdvanSiD, for a total of 6144 SiPM, achieves an overall resolution in the positron impact time of similar to 43 ps when exploiting multiple measurements. To additionally improve this resolution, 4x4 mm(2), 40 mu m cell SiPMs have been selected to substitute a fraction of the old ones (about 1000 of them overall). By means of an automated test system, a first group of them has been characterized (measuring their breakdown voltage and their I-V curves), to match as much as possible SiPMs with the same gains in each pixel, in order to maximize the pixel time resolution. Such automated test system will be presented, together with some preliminary results on single pixel time resolution and the expectations of the average time resolution of the pTC in the coming years.

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.

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.

A bakelite double gap Resistive Plate Chamber (RPC), operating in avalanche mode, has been exposed to the radiation emitted from a 252Cf source to measure its neutron and gamma sensitivity. One of the two gaps underwent the traditional electrodes surface coating with linseed oil. RPC signals were triggered by fission events detected using BaF2 scintillators. A Monte Carlo code, inside the GEANT 3.21 framework with MICAP interface, has been used to identify the gamma and neutron contributions to the total number of collected RPC signals. A neutron sensitivity of (0.63±0.02)×10−3 (average energy 2 MeV) and a gamma sensitivity of (14.0±0.5)×10−3 (average energy 1.5 MeV) have been measured in double gap mode. Measurements done in single gap mode have shown that both neutron and gamma sensitivity are independent of the oiling treatment.

RPC neutron sensitivity has been studied during two tests done with different neutrons energies. In the first test, neutrons from spontaneous fission events of 252Cf were used (average energy 2MeV); while in the second test neutrons were produced using a 50MeV deuteron beam on a 1cm thick beryllium target (average energy 20MeV). Preliminary results show that the neutron sensitivity in double gap mode is (0.52±0.03)×10−3 at about 2MeV and (5.3±0.5)×10−3 at about 20MeV.

We have developed a new integrating 12-bit analog-to-digital converter with independent gates. The circuit is especially designed for fast neutron spectrometry at very low intensity fields using multi-cell liquid scintillator detectors. A detailed layout and the main performances of the electronic circuit are described.

A novel version of the front-end electronics for the CMS Resistive Plate Chambers is described. It is based on a new front-end ASIC, designed and manufactured in the 0.8μm BiCMOS technology by Austria Mikro Systeme. The main improvements with respect to the previous version (Loddo et al., Proceedings of the Fourth International Workshop on Resistive Plate Chambers and related Detectors, Napoli, 15–16 October 1997) [1] concern the input impedance, the threshold uniformity and the timing performance. Simulation and test results will be shown, together with a brief description of the automatic test system for both front-end chip and board.

MIDAS (MIcrostrip Detector Array System) is a compact silicon tracking telescope for charged particles emitted at small angles in intermediate energy photonuclear reactions. It was realized to increase the angular acceptance of the DAPHNE detector and used in an experimental program to check the Gerasimov-Drell-Hearn sum rule at the Mainz electron microtron, MAMI. MIDAS provides a trigger for charged hadrons, p/pi identification and particle tracking in the region 7 deg < theta < 16 deg. In this paper we present the main characteristics of MIDAS and its measured performances.

A low-cost high-performance pulse-shape discriminator for neutron-gamma discrimination using liquid scintillation counters equipped with two photomultipliers is developed. Two independent methods of pulse-shape discrimination are exploited to achieve an optimum neutron-gamma identification. The circuit is especially designed to study the low-intensity neutron background field in the Gran Sasso underground laboratory. A detailed layout and the main performances of the electronic circuit are described. (C) 1998 Elsevier Science B.V. All rights reserved.