S. Suzuki

Scintillation efficiency of nuclear recoil in liquid xenon

Abstract We present the results of a test done with a Liquid Xenon (LXe) detector for “Dark Matter” search, exposed to a neutron beam to produce nuclear recoil events simulating those which would be generated by WIMPs elastic scattering. The aim of the experiment was to measure directly the scintillation efficiency of nuclear recoil. The nuclear recoil considered in the test was in the tens of keV range. The ratio of measured visible energy over the true recoil energy was evaluated to be about 20%, in good agreement with the theoretical predictions.

Performance of a liquid argon time projection chamber exposed to the CERN West Area Neutrino Facility neutrino beam

F. Arneodo, P. Benetti, M. Bonesini, A. Borio di Tigliole, B. Boschetti, A. Bueno, E. Calligarich, F. Casagrande, a D. Cavalli, F. Cavanna, P. Cennini, S. Centro, E. Cesana, D. Cline, A. Curioni, b I. De Mitri, C. De Vecchi, 2 R. Dolfini, A. Ferrari, A. Ghezzi, A . Guglielmi, J. Kisiel, G. Mannocchi, A. Mart́ınez de la Ossa, C. Matthey, F. Mauri, C. Montanari, S. Navas, P. Negri, M. Nicoletto, S. Otwinowski, M. Paganoni, O. Palamara, A. Pepato, L. Periale, G. Piano Mortari, P. Picchi, 5 F. Pietropaolo, A. Puccini, A. Pullia, S. Ragazzi, T. Rancati, A. Rappoldi, G.L. Raselli, N. Redaelli, E. Rondio, A. Rubbia, C. Rubbia, P.R. Sala, F. Sergiampietri, J. Sobczyk, S. Suzuki, 5, c T. Tabarelli de Fatis, M. Terrani, F. Terranova, A. Tonazzo, S. Ventura, C. Vignoli, H. Wang, and A. Zalewska

Detection of scintillation light in coincidence with ionizing tracks in a liquid argon time projection chamber

A system to detect light from liquid argon scintillation has been implemented in a small, ICARUS-like, liquid argon time projection chamber. The system, which uses a VUV-sensitive photomultiplier to collect the light, has recorded many ionizing tracks from cosmic-rays in coincidence with scintillation signals. Our measurements demonstrate that scintillation light detection can provide an effective method for absolute time measurement of events and eventually a useful trigger signal

Calibration of BC501A liquid scintillator cells with monochromatic neutron beams

Abstract The recoil proton energy response has been measured by exposing cylindrical cells, filled with BC501A BICRON liquid scintillator, to mono-energetic neutron reference fields. We determine the required calibration parameters and report the detailed procedures for the experimental data handling. A dedicated Monte Carlo simulation of the detector response and efficiency has been performed. It showed good agreement with the measured quantities. The results from this calibration are necessary for a detailed study of the neutron spectrum at the underground Gran Sasso Laboratory, with a neutron detector made of 32 liquid scintillator cells, like those used during the calibration.

Performance evaluation of a hit finding algorithm for the ICARUS detector

Abstract A procedure to filter the ICARUS digitized data is presented. The final multi-kiloton detector will provide raw data at a rate of the order of 100xa0Gbytes/s and therefore a crucial element of the acquisition chain will be the on-line data reduction system. A filter has been developed to process the signals and to tag the meaningful data. The hit detection efficiency has been evaluated on a sample of signals obtained from cosmic rays events in the 3xa0t ICARUS prototype. Its robustness has been tested also on simulated events with different signal to noise ratio. The hit finder hardware implementation is also presented.

ICARUS. A status report

Abstract The latest evolutions of the ICARUS project are reviewed. During the present year the collaboration has been heavily involved into the construction of the first full scale prototypes of the 600 ton ICARUS detector. Cryogenic and purification tests as well as mechanical tests on a wires chamber module, are presently under completion. No major problems were found and we foresee to be ready for the commissioning of the major detector components by the end of the present year. Also, the Long Baseline Neutrino Oscillation program has been subject to a rapid acceleration. Following our formal proposal, submitted and approved at the beginning of this year by the CERN SPSLC, a working group has been formed to study the details of the beam and a sensitive program has been formulated by which first neutrinos can be sent to the Gran Sasso at the end of year 2001.

Study of solar neutrinos with the 600 t liquid argon ICARUS detector

Abstract The ICARUS time projection chamber can yield sound information on 8 B solar neutrinos. Owing to the high-energy resolution and the good capability of event reconstruction it can make a contribution to our understanding of neutrino intensities and their energy spectrum. Moreover, the MSW oscillation probability for sterile and active neutrinos can be well studied because both elastic scattering by electrons and absorption reaction on argon nuclei can be measured independently. The main problem in detecting the low-energy neutrino interactions arises from the environmental radioactivity. In the present work we study by Monte Carlo simulation the topology and the rates of the events, induced by neutrinos and background neutrons, in a 470 t (fiducial mass) liquid-argon TPC detector. For neutrino interactions we use the standard solar model BP98 and the recent experimental confirmation of the shell model computation of absorption cross section. The noise is estimated from new data on natural neutron background, collected in the hall C of the Gran Sasso laboratory. It is confirmed that, with a relatively modest neutron shielding and particular off-line event triggers, the weight of spurious events can be made to have little influence on the ICARUS solar neutrino measurement. Indeed, we expect 6 (26) background events per year in the 212 (759) elastic scattering (absorption reaction) sample.

ICARUS 600 ton: A status report

The goal of the ICARUS Project is the installation of a multi-kiloton LAr TPC in the underground Gran Sasso Laboratory. The programme foresees the realization of the detector in a modular way. The first step is the construction of a 600 ton module which is now at an advanced phase. It will be mounted and tested in Pavia in one year and then it will be moved to Gran Sasso for the final operation. The major cryogenic and purification systems and the mechanical components of the detector have been constructed and tested in a 10 m3 prototype. The results of these tests are here summarized.