[en] Decrease in operating temperature of a silicon photomultiplier (SiPM) reduces its dark noise. Some experiments consider low temperatures to take advantage of this possibility. And one of them is the TAO detector. It requires operation at $T\approx -50°\mathrm{C}$. In this paper, the studies of operation of both Hamamatsu SiPMs and AdvanSID SiPMs in a temperature range of −100 °C to 23 °C are presented.

[en] Micropixel avalanche photodiodes (MAPDs) are new instruments for detecting low-intensity light. They consist of many microcounters (pixels integrated on a common silicon wafer). A unique design by the Joint Institute for Nuclear Research (JINR) (Z. Sadygov)—deep-microwell MAPD—provides an order of larger pixel densities without losses in photon-detection efficiency. These instruments are beginning to find use in precision electromagnetic calorimetry. MAPDs can be most widely applied as photodetectors in scanners for positron-emission tomographs (PETs), particularly the time-of-flight PETs becoming popular now. The possibility of using MAPDs in PETs is shown, and the time resolution of a pair of quanta detected by Lutetium Fine Silicate scintillation crystals with MAPD readout is obtained at the level of 400 ps.

[en] A modular liquid argon (LAr) Time Projection Chamber (TPC) with pixelated charge readout is considered as a part of the near-detector for the Deep Underground Neutrino Experiment (DUNE) [1]. Such a TPC is being developed by the ArgonCube collaboration [2]. To provide a trigger for the data acquisition (DAQ) of a neutrino event the LAr scintillation light detection is proposed. The light is a vacuum ultraviolet (UV) with 128 nm wavelength, thus, it is a challenge to register it. The main requirements imposed on the light detection system are a good performance at cryogenic temperatures, non-conductive materials, compact dimensions, and a detection efficiency at a level of percent. A Light Collection Module (LCM) as a candidate for the system has been developed at Joint Institute for Nuclear Research (JINR) in Dubna, Russia. The LCM is based on the wavelength-shifting (WLS) fibers that are coated with Tetraphenyl Butadiene (TPB) and read out by silicon photomultipliers (SiPM). Also at JINR, a full readout chain for the light detection system has been developed, consisting of the front-end electronics, power-supply for the SiPMs, and the DAQ. A cryogenic test setup has been built at JINR to study the performance of the LCM in LAr. A similar study was carried out in the laboratory for high energy physics of Bern University with highly purified LAr. These studies have shown that the photon detection efficiency (PDE) of the LCM for the LAr scintillation light is about 1–2%. Further tests in the ArgonCube prototype TPC will provide the real performance of the LCM system with a full readout chain.

[en] ECAL0 is a new electromagnetic calorimeter designed for studying generalized parton distributions at the COMPASS II experiment at CERN. It will be located next to the target and will cover larger photon angles (up to 30 degrees). It is a modular high-granularity Shashlyk device with total number of individual channels of approx. 1700 and readout based on wavelength shifting fibers and micropixel avalanche photodiodes. Characterization of the calorimeter includes tests of particular sub-components, tests of complete modules and module arrays, as well as a pilot run of a fully-functional, quarter-size prototype in the COMPASS experiment. The main goals of the tests on low-intensity electron beam at the ELSA accelerator in Bonn were: to provide energy calibration using electrons, to measure angular response of the calorimeter and to perform an energy scan to cross-check previously collected data. A dedicated measurement setup was prepared for the tests, including a 3x3 array of the ECAL0 modules, a scintillating-fibre hodoscope and a remotely-controlled motorized movable platform. The measurements were performed using three electron energies: 3.2 GeV, 1.6 GeV and 0.8 GeV. They include a calibration of the whole detector array with a straight beam and multiple angular scans

[en] The new-generation high-granularity Shashlyk EM calorimeter readout by micropixel avalanche photodiodes (MAPD) with precision thermostabilization based on the Peltier element is designed, constructed end tested. MAPD-3N with superhigh pixel density 1.5×10⁴ mm⁻² and area 3×3 mm² manufactured by the Zecotek Company were used in the photodetector unit

[en] Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality Q"2 > 1 (GeV/c)"2. The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam impinging on a polarised "6LiD target. By analysing the full range in hadron transverse momentum p_T, the different p_T-dependences of the underlying processes are separated using a neural-network approach. In the absence of pQCD calculations at next-to-leading order in the selected kinematic domain, the gluon polarisation Δg/g is evaluated at leading order in pQCD at a hard scale of μ"2 = left angle Q"2 right angle = 3 (GeV/c)"2. It is determined in three intervals of the nucleon momentum fraction carried by gluons, x_g, covering the range 0.04 < x_g < 0.28 and does not exhibit a significant dependence on x_g. The average over the three intervals, left angle Δg/g right angle = 0.113 ± 0.038_(_s_t_a_t_._) ± 0.036_(_s_y_s_t_._) at left angle x_g right angle ∼ 0.10, suggests that the gluon polarisation is positive in the measured x_g range. (orig.)

[en] Single hadron azimuthal asymmetries of positive and negative hadrons produced in muon semi-inclusive deep inelastic scattering off longitudinally polarised deuterons are determined using the 2006 COMPASS data and also combined all deuteron COMPASS data. For each hadron charge, the dependence of the azimuthal asymmetry on the hadron azimuthal angle φ is obtained by means of a five-parameter fitting function that besides a φ-independent term includes four modulations predicted by theory: sin φ, sin 2φ, sin 3φ and cos φ. The amplitudes of the five terms have been extracted, first, for the hadrons in the whole available kinematic region. In further fits, performed for hadrons from a restricted kinematic region, the φ-dependence is determined as a function of one of three variables (Bjorken-x, fractional energy of virtual photon taken by the outgoing hadron and hadron transverse momentum), while disregarding the others. Except the φ-independent term, all the modulation amplitudes are very small, and no clear kinematic dependence could be observed within experimental uncertainties. (orig.)