[Show abstract][Hide abstract] ABSTRACT: This paper presents a complete description of Virgo, the French-Italian gravitational wave detector. The detector, built at Cascina, near Pisa (Italy), is a very large Michelson interferometer, with 3 km-long arms. In this paper, following a presentation of the physics requirements, leading to the specifications for the construction of the detector, a detailed description of all its different elements is given. These include civil engineering infrastructures, a huge ultra-high vacuum (UHV) chamber (about 6000 cubic metres), all of the optical components, including high quality mirrors and their seismic isolating suspensions, all of the electronics required to control the interferometer and for signal detection. The expected performances of these different elements are given, leading to an overall sensitivity curve as a function of the incoming gravitational wave frequency. This description represents the detector as built and used in the first data-taking runs. Improvements in different parts have been and continue to be performed, leading to better sensitivities. These will be detailed in a forthcoming paper.
Journal of Instrumentation 03/2012; 7(03):P03012. · 1.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Journal of Instrumentation 04/2009; 4(04):P04018. · 1.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The OPERA neutrino oscillation experiment is based on the use of the Emulsion Cloud Chamber (ECC). In the OPERA ECC, nuclear emulsion films acting as very high precision tracking detectors are interleaved with lead plates providing a massive target for neutrino interactions. We report on studies related to the effects occurring from the contact between emulsion and lead. A low radioactivity lead is required in order to minimize the number of background tracks in emulsions and to achieve the required performance in the reconstruction of neutrino events. It was observed that adding other chemical elements to the lead, in order to improve the mechanical properties, may significantly increase the level of radioactivity on the emulsions. A detailed study was made in order to choose a lead alloy with good mechanical properties and an appropriate packing technique so as to have a low enough effective radioactivity.
Journal of Instrumentation 07/2008; 3(07):P07002. · 1.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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 νμ→ντ oscillations.
Journal of Instrumentation 03/2007; 2(03):T03001. · 1.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The design and construction of the 990-ton gapless iron magnets for the OPERA experiment represent a major challenge from the point of view of mechanics, electric and heat engineering. Two of such magnets have been built in a deep underground hall of the Gran Sasso laboratories between 2003 and 2006 and they have been switched on for the first time in March 2006. In this paper we discuss the construction and characterization of these devices. First experience with the CNGS beam are also reported.
[Show abstract][Hide abstract] ABSTRACT: 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 νμ → ντ 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 Journal of Physics 12/2006; 8(12):303. · 4.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The construction and commissioning of the 990-ton gapless iron magnets for the OPERA experiment is presented. These magnets have been built in a deep underground hall of the Gran Sasso laboratories between 2003 and 2006 and they have been switched on for the first time in March 2006. In this poster we discuss the mechanic, electric and thermal characterization of these devices as well as measurements of the magnetic field by means of pickup coils. Moreover, we discuss the commissioning of the auxiliary systems (power supply, water cooling plant); first neutrino beam has been sent in August 2006 and is also reported.
[Show abstract][Hide abstract] ABSTRACT: The OPERA neutrino oscillation experiment foresees the construction of two magnetized iron spectrometers located after the lead-nuclear emulsion targets. The magnet is made up of two vertical walls of rectangular cross section connected by return yokes. The particle trajectories are measured by high precision drift tubes located before and after the arms of the magnet. Moreover, the magnet steel is instrumented with resistive plate chambers that ease pattern recognition and allow a calorimetric measurement of the hadronic showers. In this paper, we review the construction of the spectrometers. In particular, we describe the results obtained from the magnet and RPC prototypes and the installation of the final apparatus at the Gran Sasso laboratories. We discuss the mechanical and magnetic properties of the steel and the techniques employed to calibrate the field in the bulk of the magnet. Moreover, results of the tests and issues concerning the mass production of the resistive plate chambers are reported. Finally, the expected physics performance of the detector is described; estimates rely on numerical simulations and the outcome of the tests described above.
IEEE Transactions on Nuclear Science 07/2004; · 1.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The OPERA neutrino oscillation experiment foresees the construction of two magnetized iron spectrometers located after the instrumented lead-nuclear emulsion targets. The spectrometer consists of a dipolar magnet without air gaps. The driving coils are located in the return yokes which are connected by two columns of iron slabs interleaved with Resistive Plate Chambers. The particle trajectories are measured by layers of vertical drift tube planes located before and after the magnet. In this paper we review the construction of the spectrometers. In particular, we describe the results obtained front the magnet and RPC prototypes and the installation of the final apparatus at Gran Sasso. We present the ballistic techniques employed to calibrate the field in the bulk of the magnet and the results in term of field uniformity and magnetic properties of the iron. Moreover, we demonstrate that a field calibration at the level of 3% can be reached and we discuss the limiting systematics. The mass production of RPC started in Jan 2003. Results of the tests and issues concerning the mass production are reported. Finally, the expected physics performance of the detector is described; estimates rely on numerical simulations and the outcome of the tests described above.
[Show abstract][Hide abstract] ABSTRACT: The experimental problem of the calibration of magnetic field in large iron detectors located in underground areas is discussed. Emphasis is laid on techniques based on ballistic measurements as the ones employed by MINOS or OPERA. An experimental investigation of the precision achievable by these methods has been carried out using a full-scale prototype of the OPERA spectrometer built in Frascati in 2001. We demonstrate that a field calibration at the level of 3% can be reached and discuss in details the limiting systematics. Moreover, we provide analytical formulas to model the behaviour of the apparatus in the transient regime, keeping into account eddy current effects and the finite penetration velocity of the driving fields. These formulas ease substantially the design of the calibration apparatus. Finally, ballistic techniques are shown to match the requirements for field calibration at the next generation long-baseline neutrino experiments and are well-suited to operate in underground laboratories.
[Show abstract][Hide abstract] ABSTRACT: The performance of the ALEPH detector at the LEP e+e− collider is reviewed. The accuracy of the tracking detectors to measure the impact parameter and momentum of charged tracks is specified. Calorimeters are used to measure photons and neutral hadrons, and the accuracy obtained in energy and angle is given. An essential property of the detector is its ability to identify particles; the performance in identification of electrons, muons, neutrinos (from missing energy), charged hadrons, π0's and V0's is described.
[Show abstract][Hide abstract] ABSTRACT: The manufacturing process of a series of position sensitive silicon detectors is described together with the tests performed to optimize the performance of the detectors. The detectors are Schottky diodes with strips on the ohmic contract which allow to determine the position of the incoming ionizing particles by charge partition.Four detectors were assembled in a telescope and tested inside the vacuum pipe of the Tevatron Collider at Fermilab. The system is a prototype of the Small Angle Silicon Spectrometer, designed primarily to study elastic and diffractive cross sections, and is a part of the Collider Detector of Fermilab (CDF).Several tests were performed to check the efficiency and the linearity of response of various regions of the detectors. Scans of the beam halo were also done both in high and low β optics to check how close to the beam the detectors could be operated. Finally, the dependence of the detector response on temperature and integrated radiation dose was investigated.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/1987; 253(3):537–541. · 1.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Four position sensitive silicon detectors have been tested inside the Tevatron beam pipe at Fermilab. The system is the prototype of the small angle silicon spectrometer designed to study primarily elastic and diffractive cross-sections at the Collider of Fermilab (CDF).Particles in the beam halo during storage tests were used to study the performance of the detectors. Efficiency, linearity of response and spatial resolution are shown. Measurements performed at different distances from the beam axis have shown that the detectors could be operated at 8.5 mm from the beam with low rates and no disturbance to the circulating beams. This distance corresponds to about 11 times the standard half-width of the local beam envelope.The behaviour of the detectors with the radiation dose has also been investigated.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 12/1986; 252(s 2–3):467–470. · 1.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The physics goals that can be pursued using silicon detectors at very small angles inside the Tevatron beam pipe are discussed. These goals span a wide field, covering measurements of luminosity, elastic scattering, diffraction dissociation, determination of the total cross section and search for new phenomena in large mass diffraction dissociation. 8 figs., 5 tabs.