We summarize here the results of the TARC experiment whose main purpose is to demonstrate the possibility of using Adiabatic Resonance Crossing (ARC) to destroy efficiently Long-Lived Fission Fragments (LLFFs) in accelerator-driven systems and to validate a new simulation developed in the framework of the Energy Amplifier programme. An experimental set-up was installed in a CERN PS proton beam line to study how neutrons produced by spallation at relatively high energy (En⩾1MeV) slow down quasi-adiabatically with almost flat isolethargic energy distribution and reach the capture resonance energy of an element to be transmuted where they will have a high probability of being captured. Precision measurements of energy and space distributions of spallation neutrons (using 2.5 and 3.5 GeV/c protons) slowing down in a 3.3 m×3.3 m×3 m lead volume and of neutron capture rates on LLFFs 99Tc, 129I, and several other elements were performed. An appropriate formalism and appropriate computational tools necessary for the analysis and understanding of the data were developed and validated in detail. Our direct experimental observation of ARC demonstrates the possibility to destroy, in a parasitic mode, outside the Energy Amplifier core, large amounts of 99Tc or 129I at a rate exceeding the production rate, thereby making it practical to reduce correspondingly the existing stockpile of LLFFs. In addition, TARC opens up new possibilities for radioactive isotope production as an alternative to nuclear reactors, in particular for medical applications, as well as new possibilities for neutron research and industrial applications.

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, a self supporting structure made of light composite materials and a low cost. A spatial resolution of 150 microns has been achieved with a single hit efficiency of 97

Energy and space distributions of spallation neutrons (from 2.5 and 3.57 GeV/c CERN proton beams) slowing down in a 3.3 × 3.3 × 3 m3 lead volume and neutron capture rates on long-lived fission fragments 99Tc and 129I demonstrate that Adiabatic Resonance Crossing (ARC) can be used to eliminate efficiently such nuclear waste and validate innovative simulation.

This note describes the performance of modules assembled with up to 12 silicon microstrip detectors. These modules were built for the instrumented Silicon Target (STAR) that has been installed in the NOMAD spectrometer. Laboratory and test beam results are compared with model predictions. For a module of nine detectors, test beam results indicate a signal-to-noise ratio of 19, a hit finding efficiency of 99.8% and a spatial resolution of 6.0μm. Laboratory measurements indicate that modules of twelve detectors exhibit a signal-to-noise ratio of the order of 16.

The NOMAD experiment is a short base-line search for νμ − ντ oscillations in the CERN neutrino beam. The ντ's are searched for through their charged current interactions followed by the observation of the resulting τ− through its electronic, muonic or hadronic decays. These decays are recognized using kinematical criteria necessitating the use of a light target which enables the reconstruction of individual particles produced in the neutrino interactions. This paper describes the various components of the NOMAD detector: the target and muon drift chambers, the electromagnetic and hadronic calorimeters, the preshower and transition radiation detectors and the veto and trigger scintillation counters. The beam and data acquisition system are also described. The quality of the reconstruction and individual particles is demonstrated through the ability of NOMAD to observe Ks0's, Λ0's and π0's. Finally, the observation of τ− through its electronic decay being one of the most promising channels in the search, the identification of electrons in NOMAD is discussed.

A transition radiation detector to identify electrons at 90% efficiency with a rejection factor against pions of 103 on an area of 2.85 × 2.85 m2 has been constructed for the NOMAD experiment. Each of its 9 modules includes a 315 plastic foil radiator and a detector plane of 176 vertical straw tubes filled with a xenon-methane gas mixture. Details of the design, construction and operation of the detector are given.

This note describes the construction of a target for neutrino interactions composed of passive boron carbide plates interleaved with silicon microstrip detectors. The target contains four layers of passive material with a total mass of 45 kg and 600 single-sided silicon microstrip detectors with a total surface of 1.14 m2 distributed over five layers. It is installed in the NOMAD spectrometer at the CERN SPS neutrino beam. During the 1997 run about 8000νμ charged current interactions were estimated to have occurred in the target. For these events it will be possible to perform a precise measurement of both vertex and kinematical variables. This will provide invaluable experience towards the construction of a future large-scale silicon tracker for neutrino oscillation experiments.

This note describes the performance of modules assembled with up to twelve silicon microstrip detectors. These modules were built for the instrumented Silicon Target (STAR) that has been installed in the NOMAD spectrometer. Laboratory and test beam results are compared with model predictions. For a module of nine detectors, test beam results indicate a signal{to{noise ratio of 19, a hit nding e ciency of 99.8% and a spatial resolution of 6.0 m. Laboratory measurements indicate that modules of twelve detectors exhibit a signal{to{noise ratio of the order of 16. a. University of Padua, Padua, Italy. b. CERN, Geneva, Switzerland. c. Harvard University, Cambridge, MA, USA. d. University of Sydney, Sydney, Australia. e. LAPP, Annecy, France. f . University of Valencia, Valencia, Spain. g. Joint Institute for Nuclear Research, Dubna, Russia. h. Dortmund University, Dortmund, Germany. i. University of Lausanne, Lausanne, Switzerland. j. Rudjer Bo skovi c Institute, Zagreb, Croatia. k. University of Urbino, Urbino and INFN, Florence, Italy. Submitted to Nuclear Instrumentation and Methods. Now at University of Geneva, Geneva, Switzerland. Now at University of California at Santa Cruz, California, USA. On leave of absence from Institute of Electron Technology, Warsaw, Poland.

The NOMAD experiment is a short base-line search for νμ → ντ oscillations in the CERN neutrino beam. The ντ ’s are searched for through their charged-current interactions followed by the observation of the resulting τ− through its electronic, muonic or hadronic decays. These decays are recognized using kinematical criteria necessitating the use of a light target which enables the reconstruction of individual particles produced in the neutrino interactions. This paper describes the various components of the NOMAD detector: the target and muon drift chambers, the electromagnetic and hadronic calorimeters, the preshower and transition radiation detectors, and the veto and trigger scintillation counters. The beam and data acquisition system are also described. The quality of the reconstruction of individual particles is demonstrated through the ability of NOMAD to observe Ks ’s, Λ 0’s and π0’s. Finally, the observation of τ− through its electronic decay being one of the most promising channels in the search, the identification of electrons in NOMAD is discussed.

In the R&D programme for the ICARUS experiment, we have developed a practical procedure to purify liquid argon in the liquid phase. Extreme purity is obtained, corresponding to an electronegative impurity concentration below 0.1 ppb of 02 equivalent. This corresponds to an electron lifetime in the range of several milliseconds equivalent to attenuation length of a few metres. The procedure has been tested up to flows of the order of 1000 litres of liquid per hour. The new technique makes it possible to operate very large amounts of ultrapure liquid argon as foreseen for the multikiloton ICARUS experiment at Gran Sasso.

A section of the UA1 uranium/tetramethylpentane forward calorimeter has been tested with muon and electron beams from the CERN Super Proton Synchrotron. The module has a semi-octagonal shape, so that it will closely surround the beam pipe in the end-cap calorimeter region. The mechanical and electrical requirements of this design, needed to provide a full hermeticity for a large detector, have been successfully solved to achieve an excellent overall response of the calorimeter.

A uranium tetramethylpentane hadronic calorimeter has been tested using electrons and pions of 7 GeV/c momentum with electric fields varying from 0.8 to 16.0 kV/cm; the e/π charge collection ratio has been measured as a function of the electric field within this range. It is observed that the e/π ratio can be tuned acting on the electric field without spoiling the energy resolution for electrons. At the same time the energy resolution for pions is improved. The effect was cross-checked using a second module and 40 GeV/c electron and pion beams.

A calorimeter, consisting of uranium plates and thin liquid ionization chambers filled with tetramethylpentane (TMP) at room temperature, has been tested using electrons between 10 and 70 GeV. The essential characteristics of the liquid are discussed, including measurements of the free electron lifetime. Results on uniformity, linearity and energy resolution are described and some information on the response to hadrons has been obtained. A single TMP box containing four electrodes and a TMP position detector for electromagnetic showers have also been tested.

We describe the construction and performance of the improved muon detection system of the UA1 experiment. The new position detectors, that complement the original muon detection system based on large planar drift chambers, are limited-streamer chambers for a total surface of 800 m2. The coordinate parallel to the wires is readout through the especially developed STAR electronics that integrates and digitizes the signal from the strips. The intrinsic spatial resolution, determined in a test beam, is 400 μm, that achieved so far in the real system is 1.2 mm. The efficiency is evaluated to be (94.9±0.6)%.

The Central Detector of the UA1 experiment at the CERN proton-antiproton Collider underwent a first physics run at the end of 1981. The detector consists of a large drift chamber assembly (25 m3, ~ 6000 sense wires). An electronics readout with multi-hit capability simultaneously digitizes the time and the analog information used for charge division and energy measurement. The initial performance of the readout and control system will also be presented. The detector was tested in two cosmic-ray runs, and is now fully operational for the second physics run; this started at the beginning of October 1982.

The UAl Central Detector is now taking data at the CERN pp Collider1~2. W e give a general desc r iption of the detector and discuss the aspects that are mainly related to its quality and reliability. Multi-hit electronics is used for the readout of 6000 sense wires uniformly distributed over 25 m'. The analog informa' tion, energy, and charge division, is digitized on line every 32 ns. The high density and the precision of the points detected along the t racks is such that the reconstructed events look s imilar to bubble chamber pictures. Results obtained in the first phys ic s runs are presented.

The construction of a large (25 m3, 23 000 wires) drift chamber assembly with image readout to be used at the CERN p-p collider facility is reported. In this contribution the emphasis is mainly directed towards the mechanical and electrostatic design and on the implementation of the various control procedures.

A set of proportional chambers has been constructed for a multiparticle spectrometer at the CERN Intersecting Storage Rings (ISR). The detector consists of 73 000 wires and covers an effective area of 300 m2. In this paper we will describe the design and performance of this detector.

A multiparticle spectrometer at the CERN Intersecting Storage Rings is equipped with proportional chambers as detectors. In this paper we describe design and performance of the vertex detector around the collision region. The detector consists of ∼20 000 proportional wires in densely packed chambers.