[en] A new magnet system designed for use in the polarized target of the COMPASS experiment has been delivered. The magnetic field measurements results of the two campaigns made at CEA Saclay and at CERN are presented in this paper. (authors)

[en] We implemented a low noise current preamplifier for the readout of resistive bolometers. We tested the apparatus on thermometer resistances ranging from 10 to 500 MΩ. The use of current preamplifier overcomes constraints introduced by the readout time constant due to the thermometer resistance and the input capacitance. Using cold JFETs, this preamplifier board is shown to have very low noise: the Johnson noise of the source resistor (1 fA/Hz^1/2) dominated in our noise measurements. We also implemented a lock-in chain using this preamplifier. Due to fast risetime, compensation of the phase shift may be unnecessary. If implemented, no tuning is necessary when the sensor impedance changes. Transients are very short, and thus low-passing or sampling of the signal is simplified. In case of spurious noise, the modulation frequency can be chosen in a much wider frequency range, without requiring a new calibration of the apparatus

[en] In the Atlas muon spectrometer (ATLAS Technical Proposal, CERN/LHCC/94-43, 15 December 1994, ATLAS Muon Spectrometer Technical Design Report, CERN/LHCC/97-22, 31 May 1997 and http://atlasinfo.cern.ch:80/Atlas/Welcome.html) the alignment system should control the spatial position of the muon chambers with an accuracy of 30 μm and 200 μrad for a range of ±5 mm and ±10 mrad. The alignment device described in this paper, called Praxial, fulfills these requirements

[en] We have developed two different optical systems in order to position detectors with respect to a reference laser beam. The first system, a telescope, permits the absolute positioning of an element with respect to a reference laser beam. The resolution is of the order of 10 μm in translation and 50 μrad in rotation. It is highly transparent (∼90%) permitting several elements to be aligned. A calibration procedure has also been studied and is currently being tested in order to obtain an absolute alignment information. The second system is a highly transparent (95%) two-dimensional position sensor which allows the accurate positioning (below 20 μm) of several (up to 10) elements to which each sensor is attached, transversally to a laser beam used as a reference straight line. The present useful area of the first sensor is 20x20 mm² and is 15x15 mm² for the second. In both cases it can be further increased to meet the experiment's requirement

[en] We have developed two different optical systems in order to position detectors with respect to a reference laser beam. The first system, a telescope, permits the absolute positioning of an element with respect to a reference laser beam. The resolution is of the order of 10 μm in translation and 50 μrad in rotation. It is highly transparent (-90%) permitting several elements to be aligned. A calibration procedure has also been studied and is currently being tested in order to obtain an absolute alignment information. The second system is a highly transparent (95%) two dimensional position sensor which allows the accurate positioning (below 20 μm) of several (up to ten) elements to which each sensor is attached, transversally to a laser beam used as a reference straight line. The present useful area of the first sensor is 20 x 20 mm² and is 15 x 15 mm² for the second. In both case it can be further increased to meet the experiment's requirement. (authors)

[en] Results from the Trainou tall tower measurement station installed in 2006 are presented for atmospheric measurements of CO₂, CH₄, N₂O, SF₆, CO, H₂ mole fractions and radon-222 activity. Air is sampled from four sampling heights (180, 100, 50 and 5 m) of the Trainou 200 m television tower in the Orleans forest in France (475705300 N, 20604500 E, 131 ma.s.l.). The station is equipped with a custom-built CO₂ analyser (CARIBOU), which is based on a commercial non-dispersive, infrared (NDIR) analyser (Licor 6252), and a coupled gas chromatography (GC) system equipped with an electron capture detector (ECD) and a flame ionization detector (FID) (HP6890N, Agilent) and a reduction gas detector (PP1, Peak Performer). Air intakes, pumping and air drying system are shared between the CARIBOU and the GC systems. The ultimately achieved short-term repeatability (1 sigma, over several days) for the GC system is 0.05 ppm for CO₂, 1.4 ppb for CH₄, 0.25 ppb for N₂O, 0.08 ppb for SF₆, 0.88 ppb for CO and 3.8 for H₂. The repeatability of the CARIBOU CO₂ analyser is 0.06 ppm. In addition to the in situ measurements, weekly flask sampling is performed, and flask air samples are analysed at the Laboratoire des Sciences du Climat et de l'Environnement (LSCE) central laboratory for the same species as well for stable isotopes of CO₂. The comparison between in situ measurements and the flask sampling showed averaged differences of 0.08±1.40 ppm for CO₂, 0.7±7.3 ppb for CH₄, 0.6±0.6 ppb for N₂O, 0.01±0.10 ppt for SF₆, 1.5±5.3 ppb for CO and 4.8±6.9 ppb for H₂ for the years 2008-2012. At Trainou station, the mean annual increase rates from 2007 to 2011 at the 180 m sampling height were 2.2 ppm yr^-1 for CO₂, 4 ppb yr^-1 for CH₄, 0.78 ppb yr^-1 for N₂O and 0.29 ppt yr^-1 for SF₆. For all species, the 180 m sampling level showed the smallest diurnal variation. Mean diurnal gradients between the 50 m and the 180 m sampling level reached up to 30 ppm CO₂, 15 ppm CH₄ or 0.5 ppb N₂O during nighttime whereas the mean gradients are smaller than 0.5 ppm for CO₂ and 1.5 ppb for CH₄ during afternoon. (authors)

[en] We present a detailed description of the drift chambers used as an active target and a tracking device in the NOMAD experiment at CERN. The main characteristics of these chambers are a large area (3·3 m²), a self-supporting structure made of light composite materials and a low cost. A spatial resolution of 150 μm has been achieved with a single hit efficiency of 97%

[en] The third phase of the Borexino experiment that's referred to as SOX is devoted to test the hypothesis of the existence of one (or more) sterile neutrinos at a short baseline (∼ 5-10 m). The experimental measurement will be made with artificial sources namely with a ¹⁴⁴Ce-¹⁴⁴Pr antineutrino source at the first stage (CeSOX) and possibly with a ⁵¹Cr neutrino source at the second one. The fixed ¹⁴⁴Ce-¹⁴⁴Pr sample will be placed beneath the detector in a special pit and the initial activity will be about 100-150 kCi. The start of data taking is scheduled for April 2018. The article gives a short description of the preparation for the first stage and shows the expected sensitivity. (authors)