The matrix of 3 x 3 modules of the EM calorimeter ECAL0 (COMPASS II) read out by MPPC S12572-010P SiPMs with the pixel density of 10(4) mm(-2) and an area of 3 x 3 mm(2) is studied in the range of electron energies 1-30 GeV. It is observed that the MPPC has additional response nonlinearity and a significantly smaller dynamic range of output signals than expected. The influence of parasitic capacitance between pixels on the pixel gain is discussed and proposed as explanation. The energy resolution of the calorimeter is measured to be sigma(E)/E = 7.1%(1 + 0.06/E)/ root E circle plus 1.4%E-0.25, where electron energy E is given in GeV.

A nine-channel photodetector unit with micropixel avalanche photodiodes (MAPD) and precision thermostabilization based on the compact Peltier module is designed and constructed. MAPD-3N with a high pixel density of 15,000 per square mm and area 3 x 3 mm(2) produced by Zecotek were used. (C) 2016 Elsevier B.V. All rights reserved.

The array of 3 × 3 modules of the electromagnetic calorimeter ECAL0 of the COMPASS experiment at CERN has been tested with an electron beam of the ELSA (Germany) facility. The dependence of the response and the energy resolution of the calorimeter from the angle of incidence of the electron beam has been studied. A good agreement between the experimental data and the results of Monte Carlo simulation has been obtained. It will significantly expand the use of simulation to optimize event reconstruction algorithms.

ECALO 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 ECALO 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.

A new-generation high-granularity Shashlyk EM calorimeter read out by micropixel avalanche photodiodes with thermostabilization based on the Peltier element is designed and constructed.

In many detectors based on scintillators the photomultiplier tubes (PMTs) are used as photodetectors. At present photodiodes are finding wide application. Solid state photodetectors allow operation in strong magnetic fields that are often present in applications, e.g. some calorimeters operating near magnets, combined PET and MRT, etc. The photon detection efficiency (PDE) of photodiodes may reach values a few times higher than that of PMTs. Also, they are rigid, compact and have relatively low operating voltage. In the last few years Micropixel Avalanche PhotoDiodes (MAPD) have been developed and started to be used. The MAPD combines a lot of advantages of semiconductor photodetectors and has a high gain, which is close to that of the PMT. Yet, they have some disadvantages, and one of them is a limited dynamic range that corresponds to a total number of pixels. The novel deep microwell MAPD with high pixel density produced by the Zecotek Company partially avoids this disadvantage. In this paper characteristics of these photodetectors are presented in comparison with the PMT characteristics. The results refer to measurements of the gain, PDE, cross-talks, photon counting and applications: beam test results of two different “Shashlyk” EM calorimeters for COMPASS (CERN) and NICA-MPD (JINR) with the MAPD readout and a possibility of using the MAPD in PET.

The OPERA detector at the Gran Sasso underground laboratory (LNGS) was used to measure the cosmic ray muon charge ratio Rμ=Nμ+/Nμ− in the TeV energy region. Rμ is shown as a function of the “vertical surface energy” Eμcosθ. A fit to a simplified model of muon production in atmosphere allowed the determination of the pion and kaon charge ratios weighted by the cosmic ray energy spectrum.

The main properties of two different Shashlyk EM calorimeter modules readout by novel micropixel avalanche photodiodes (MAPD) with microwell structure and very high density of pixels were studied at the T9 CERN PS test-beam facility. A MAPD-3A with density of pixels 1.5×104 mm−2 and area 3×3 mm2 manufactured by Zecotek Company was used in our test.

The OPERA neutrino detector in the underground Gran Sasso Laboratory (LNGS) was designed to perform the first detection of neutrino oscillations in appearance mode through the study of $\nu_\mu\to\nu_\tau$ oscillations. The apparatus consists of an emulsion/lead target complemented by electronic detectors and it is placed in the high energy long-baseline CERN to LNGS beam (CNGS) 730 km away from the neutrino source. Runs with CNGS neutrinos were successfully carried out in 2007 and 2008 with the detector fully operational with its related facilities for the emulsion handling and analysis. After a brief description of the beam and of the experimental setup we report on the collection, reconstruction and analysis procedures of first samples of neutrino interaction events.

The OPERA neutrino oscillation experiment has been designed to prove the appearance of ντ in a nearly pure νμ beam (CNGS) produced at CERN and detected in the underground Hall C of the Gran Sasso Laboratory, 730 km away from the source. In OPERA, τ leptons resulting from the interaction of ντ are produced in target units called bricks made of nuclear emulsion films interleaved with lead plates. The OPERA target contains 150000 of such bricks, for a total mass of 1.25 kton, arranged into walls interleaved with plastic scintillator strips. The detector is split into two identical supermodules, each supermodule containing a target section followed by a magnetic spectrometer for momentum and charge measurement of penetrating particles. Real time information from the scintillators and the spectrometers provide the identification of the bricks where the neutrino interactions occurred. The candidate bricks are extracted from the walls and, after X-ray marking and an exposure to cosmic rays for alignment, their emulsion films are developed and sent to the emulsion scanning laboratories to perform the accurate scan of the event. In this paper, we review the design and construction of the detector and of its related infrastructures, and report on some technical performances of the various components. The construction of the detector started in 2003 and it was completed in Summer 2008. The experiment is presently in the data taking phase. The whole sequence of operations has proven to be successful, from triggering to brick selection, development, scanning and event analysis.

The main task of the Target Tracker detector of the long baseline neutrino oscillation OPERA experiment is to locate in which of the target elementary constituents, the lead/emulsion bricks, the neutrino interactions have occurred and also to give calorimetric information about each event. The technology used consists in walls of two planes of plastic scintillator strips, one per transverse direction. Wavelength shifting fibres collect the light signal emitted by the scintillator strips and guide it to both ends where it is read by multi-anode photomultiplier tubes. All the elements used in the construction of this detector and its main characteristics are described.

The main task of the Target Tracker detector of the long basel ine neutrino oscillation OPERA experiment is to locate in which of the target elementa ry constituents, the lead/emulsion bricks, the neutrino interactions have occurred and also to give calorimetric information about each event. The technology used consists in walls of tw o planes of plastic scintillator strips, one per transverse direction. Wavelength shift ing fibres collect the light signal emitted by the scintillator strips and guide it to both ends w here it is read by multi-anode photomultiplier tubes. All the elements used in the constru ction of this detector and its main characteristics are described.

The micropixel avalanche photodiode (MAPD) is a novel photodetector with a multipixel intrinsic structure on the common silicon substrate. The typical size of each pixel is 20-30 mu m and the density is about 10(3) mm(-2). Each pixel works on the common load in the Geiger mode, where the discharge is limited by an individual quenching resistor (negative feedback like in gas Geiger counter) included in each pixel feeding chain located on the common substrate. In the Geiger mode one may get an amplification factor for a single photoelectron at the level of 10(6) at room temperature. Measurements of gain, photon detection efficiency, one photoelectron resolution, noise and dark current for different types of MAPD were performed and compared. (c) 2006 Elsevier B.V. All rights reserved.

The baseline option for Target Tracker of OPERA detector is plastic scintillator strips, 6.7m length, read with wavelength shifting (WLS) fiber. Usually such strips are supposed to be obtained by extrusion from pellets. Despite many advantages of extrusion process the strips extruded from pellet strips have low attenuation length (BAL=20–40cm) and low yield (LY). The main idea of our new method was to obtain scintillator using extrusion method but from the melt of specially polymerized plastic. Pilot setup was created and pilot batch for OPERA prototype was obtained with the 10kg/h productivity. Still, for mass production there was a necessity to adapt the production scheme and to manage quality assurance and quality control system. During mass production of scintillator strips for OPERA detector we have implemented all obtained results into production process. And we have carefully studied their influence on strip quality. The achieved average light yield is 7.2 ph.el. for OPERA strips.

The main task of the Target Tracker of the long baseline neutrino oscillation OPERA experiment, is to locate in which of the target elementary constituents, the lead/emulsion bricks, the neutrino interactions have occured and also to give calorimetric information about each event.The technology used consists in walls of two planes of long plastic scintillator strips, one per transverse direction. Wavelength shifting fibres collect the light signal emitted by the scintillator strips and guide it to both ends where it is read by multi-anode photomultiplier tubes. The Target Tracker is composed of 62 scintillating walls of a total surface of about 6000m(2). Each wall is made by assembling 4 horizontal md 4 vertical modules of 64.7 m long, scintillating strips. This detector has observed the first neutrino interactions during August 2006.In this paper we will describe all elements used for the construction and operation of this detector and we will also give its main characteristics. (C) 2007 Elsevier B.V. All rights reserved.

The new (p) over bar ((up arrow))p(up arrow) collider modes proposed for the HESR at GSI would provide new insights on the spin structure of the nucleon, even if only one of the two probes could be polarised. Drell-Yan processes are a powerful tool to access chirally odd parton distribution functions like transversity h(1)(x), without their convolution with fragmentation functions and without the suppression proper of the DIS experiments, in reactions were all the quarks taking part can be valence quarks. New insights on the relation of perturbative and non perturbative dynamics in hadron scattering could come in an earlier stage by the mean of the PANDA spectrometer and of the present HESR design. Spin asymmetries in hadron production and nucleonic form factors are discussed as well.

The OPERA neutrino detector at the underground Gran Sasso Laboratory (LNGS) was designed to perform the first detection of neutrino oscillations in appearance mode, through the study of nu_mu to nu_tau oscillations. The apparatus consists of a lead/emulsion-film target complemented by electronic detectors. It is placed in the high-energy, long-baseline CERN to LNGS beam (CNGS) 730 km away from the neutrino source. In August 2006 a first run with CNGS neutrinos was successfully conducted. A first sample of neutrino events was collected, statistically consistent with the integrated beam intensity. After a brief description of the beam and of the various sub-detectors, we report on the achievement of this milestone, presenting the first data and some analysis results.

New possibilities arising from the availability at GSI of antiproton beams, possibly polarised, are discussed. The investigation of the nucleon structure can be boosted by accessing in Drell-Yan processes experimental asymmetries related to cross-sections in which the parton distribution functions (PDF) only appear, without any contribution from fragmentation functions; such processes are not affected by the chiral suppression of the transversity functionh 1(x). Spin asymmetries in hyperon production and Single Spin Asymmetries are discussed as well, together with further items like electric and magnetic nucleonic form factors and open charm production. Counting rates estimations are provided for each physical case. The sketch of a possible experimental apparatus is proposed.

Global precision tests of the Standard Model are presented. They demonstrate its validity at the per mille level. This precision, combined with the level of agreement between measured and predicted values of the observables, allowed to determine the top quark mass with +/-5% accuracy and to constrain the Higgs mass within a narrow kinematical domain.

We describe ZFITTER. a Fortran program based on a semi-analytical approach to fermion pair production in e(+)e(-) annihilation at a wide range of centre-of-mass energies, including the PETRA. TRISTAN, LEP1/SLC, and LEP? energies. A flexible treatment of complete O(alpha) QED corrections and of some higher order contributions is made possible with three calculational chains containing different realistic sets of restrictions in the photon phase space. Numerical integrations are at most one-dimensional. Complete O(alpha) weak loop corrections supplemented by selected higher-order terms may be included. The program calculates Deltar. the Z width, differential cross-sections, total cross-sections, integrated forward-backward asymmetries, left-right asymmetries, and for tau pair production also final-state polarization effects. Various interfaces allow fits to be performed with different sets of free parameters. (C) 2001 Elsevier Science B.V. All rights reserved.