[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.
Full-text · Article · Apr 2009 · Journal of Instrumentation
[Show abstract][Hide abstract] ABSTRACT: 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.
Full-text · Article · Jul 2007 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: The OPERA experiment, designed to conclusively prove the existence of
νμ→ντ oscillations in the atmospheric sector,
makes use of a massive lead-nuclear emulsion target to observe the appearance
of ντ's in the CNGS νμ beam.
The location and analysis of the neutrino interactions in quasi real-time
required the development of fast computer-controlled microscopes able to reconstruct
particle tracks with sub-micron precision and high efficiency at a speed of ~20 cm2/h.
This paper describes the performance in particle track reconstruction of the
European Scanning System, a novel automatic microscope for the measurement
of emulsion films developed for OPERA.
Full-text · Article · May 2007 · Journal of Instrumentation
[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.
Full-text · Article · Dec 2006 · New Journal of Physics
[Show abstract][Hide abstract] ABSTRACT: This paper describes the recent development of a novel automatic computer-controlled manipulator for emulsion sheet placement and removal at the microscope object table (also called stage). The manipulator is designed for mass scanning of emulsions for the OPERA neutrino oscillation experiment and provides emulsion changing time shorter than 30 s with an emulsion sheet positioning accuracy as good as RMS.
Full-text · Article · Oct 2006 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: The use of nuclear emulsions in very large physics experiments is now possible thanks to the recent improvements in the industrial production of emulsions and to the development of fast automated microscopes. In this paper the hardware performances of the European Scanning System (ESS) are described. The ESS is a very fast automatic system developed for the mass scanning of the emulsions of the OPERA experiment, which requires microscopes with scanning speeds of in an emulsion volume of thickness.
Full-text · Article · May 2006 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: The technique of nuclear emulsions for high-energy physics experiments is being revived, thanks to the remarkable progress in measurement automation achieved in the past years. The present paper describes the features and performances of the European Scanning System, a last-generation automatic microscope working at a scanning speed of 20 cm(2)/h. The system has been developed in the framework of the OPERA experiment, designed to unambigously detect v(mu) -> v(tau) oscillations in nuclear emulsions. (c) 2005 Elsevier B.V. All rights reserved.
Full-text · Article · Oct 2005 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: The light from the OPERA scintillator walls is measured by Hama-matsu H8804MOD-1 64-anode photomultipliers. To quantize the en-ergy deposition in the Target-Tracker, a detailed characterisation of each of the 63488 individual channels is required. In the first part of this text, the test setup, as well as its performance are presented in detail, in the second part, all test procedures and the data handling are explained.