[en] Neutrino oscillations are the subject of most of the experiments looking at this particle. This mechanism uses the fact that neutrinos have mass to allow the transformation from one flavour to another one. The OPERA experiment will start to take data in spring 2006. Its goal is to proof this mechanism with no ambiguity using the appearance of tau neutrinos in the CNGS beam, which is made of muon neutrinos. This thesis presents a description of neutrino beams in general, and more precisely of the CNGS beam, which is sent from CERN to Gran Sasso in Italy. The neutrino flux are recalculated, and simulations have been performed in order to study miss positioning of the beam line elements. The OPERA detector is made of bricks containing a pile of lead plates and photographic emulsion films, of two trackers and two spectrometers. The high position resolution of the emulsions (< 1 μm ), allows to identify the τ created by the tau neutrino charged current interactions. The brick localisation is made using a scintillator array. The pattern recognition in these scintillators as well as in the spectrometers is one of the part of this thesis. Furthermore, a muon identification algorithm has been set up. It allows to reject by a factor 20 the charm background. Future of neutrino oscillation physics is the building of more and more intense neutrino beams, in order to measure the last unknown parameters (θ₁₃ and δ_CP). The project of neutrino beam from CERN to the Fr us tunnel is fully revisited in the last part of this thesis. An optimisation of all the beam line element is proposed, and allows to reach a sensitivity to θ₁₃ around one degree. (author)

[en] An optimization of the CERN SPL beam line has been performed guided by the sensitivities to the Θ₁₃ mixing angle and to the δ_CP Dirac CP violating phase. A UNO-like 440 ktons water Cerenkov detector located at 130 km from the target in a new foreseen Frejus laboratory has been used as a generic detector. Concerning the δ_CP independent Θ₁₃ sensitivity, a gain of about 20% may be reached using a 3.5 GeV proton beam with a 40 m long, 2 m radius decay tunnel compared to the up to now considered 2.2 GeV beam energy and 20 m long, 1 m radius decay tunnel. This may motivate new machine developments to upgrade the nominal SPL proton beam energy. (orig.)

[en] The EDELWEISS detector is located inside the Modane underground facility. The EDELWEISS-3 experiment searches for dark matter. Nuclear recoils are observed both by ionization and temperature measurements in Germanium bolometers; EDELWEISS-3 is an upgraded version of the EDELWEISS-2 experiment and will contain forty 800-g Ge detectors with a fully inter-digitized electrode readout scheme. Other improvements are the cryogenics, the shielding of the detectors and the front-end electronics that have been updated for improved data readout and noise reduction. Furthermore, a new analysis of EDELWEISS-2 data has been performed to extend the limits of Wimp search in the low mass region. The current status of EDELWEISS-3 will be discussed as well as the latest analysis results from EDELWEISS-2. (author)

[en] Multi-anode photomultipliers H7546 are used to readout signal from the OPERA Scintillator Tracker (CERN/SPSC 2000-028, SPSC/P318, LNGSP 25/2000; CERN/SPSC 2001-025, SPSC/M668, LNGS-EXP30/2001). A 32-channel front-end Read Out Chip prototype accommodating the H7546 has been designed at LAL. This device features a low-noise, variable gain preamplifier to correct for multi-anode non-uniformity, an auto-trigger capability 100% efficient at a 0.3 photo-electron, and a charge measurement extending over a large dynamic range [0-100] photo-electrons. In this article we describe the ASIC architecture that is being implemented for the Target Tracker in OPERA, with a special emphasis put on the designs and the measured performance

[en] The OPERA detector aims to see ν_τ appearance in the CNGS ν_μ beam as a result of neutrino oscillations. It is a hybrid detector consisting of both nuclear emulsions and electronic detectors that are discribed in this poster.

[en] The Cryogenic Underground Test (CUTE) facility will be located 2 km underground in the SNOLAB laboratory, near Sudbury (Ontario, Canada). It is primarily designed to test the performances of cryogenic detectors of the Super-Cryogenic Dark Matter Search (SuperCDMS) experiment which will be installed next to CUTE. As a facility, it will also be accessible to scientists developing innovative cryogenic detectors for rare events search like dark matter or double-beta decay. The low temperature required to operate the cryogenic detectors is reached via an advanced dry dilution refrigerator from CryoConcept (France). The ‘Ultra Quiet Technique’ (UQT^®) reduces the vibration transmission by using a proprietary gas-coupled thermal link between the two-stage pulse tube and the cryostat. In order to install the cryostat into a shielding water tank, we have developed a suspension system which decouples the cryostat from the environment with a low stiffness support, making a mechanical low-pass filter with a roll-off below 2 Hz for the vertical attenuation. We report the design choices made for the mechanical architecture to limit the vibration transmission and the material selection to achieve a low radioactive background rate in the detector. The expected background rate is less than 5 counts/day per kg of Ge detector in the 0–1 keV energy range.

[en] The instrumented targets of the OPERA neutrino experiment are complemented by two massive spectrometers based on gapless iron magnets. In 2006, a systematic assessment of their electromagnetic properties have been carried out. In this document, we report the results of such characterization and demonstrate that the achieved performance fulfill the physics requirements for the study of ν_μ→ν_τ oscillations

[en] The results of R&D of radiopure zinc molybdate (ZnMoO_4) based scintillating bolometers for the LUMINEU (Luminescent Underground Molybdenum Investigation for NEUtrino mass and nature) double-beta decay experiment are presented. A dedicated two-stage molybdenum purification technique (sublimation in vacuum and recrystallization from aqueous solutions) and an advanced directional solidification method (the low-thermal-gradient Czochralski technique) were utilized to produce high optical quality large mass (∼1 kg) ZnMoO_4 crystal boules and first "1"0"0Mo (99.5%) enriched Zn"1"0"0MoO_4 crystal scintillator (mass of ∼0.2 kg). Scintillating bolometers based on ZnMoO_4 (≈ 0.33 kg) and Zn"1"0"0MoO_4 (≈ 0.06 kg) scintillation elements and high purity Ge wafers were tested in the EDELWEISS set-up at the Modane Underground Laboratory (France). Long term low temperature tests demonstrate excellent detectors’ performance and effectiveness of the purification and solidification procedures for the achievement of high radiopurity of the material, in particular with a bulk activity of "2"2"8Th and "2"2"6Ra below 4 µBq/kg. The adopted protocol was used to produce for the first time a large volume Zn"1"0"0MoO_4 crystal scintillator (mass of ∼1.4 kg, "1"0"0Mo enrichment is 99.5%) to search for neutrinoless double-beta decay of "1"0"0Mo in the framework of the LUMINEU project

[en] The EDELWEISS-III direct dark matter search experiment uses cryogenic HP-Ge detectors Fully covered with Inter-Digitized electrodes (FID). They are operated at low fields (< 1 V/cm), and as a consequence charge-carrier trapping significantly affects both the ionization and heat energy measurements. This paper describes an analytical model of the signals induced by trapped charges in FID detectors based on the Shockley-Ramo theorem. It is used to demonstrate that veto electrodes, initially designed for the sole purpose of surface event rejection, can be used to provide a sensitivity to the depth of the energy deposits, characterize the trapping in the crystals, perform heat and ionization energy corrections and improve the ionization baseline resolutions. These procedures are applied successfully to actual data.

[en] OPERA is a dedicated experiment for the observation of ν_μ into ν_τ oscillations through τ appearance using a 730 km long baseline ν_μ beam from CERN to the Gran Sasso underground laboratory. The detector is equipped with two spectrometers for muon identification and charm background rejection. Bakelite RPCs are used as inner trackers inside the iron magnet of the spectrometers. The experiment has already performed two short runs in 2006 and 2007. Results about the RPC performances are presented.