P. Cennini

Experimental determination of the energy generated in nuclear cascades by a high energy beam

An already existing, sub-critical arrangement made of natural uranium and water moderator has been exposed to a low intensity (≈ 109 ppp) proton beam from CERN-PS at several kinetic energies from 600 MeV to 2.75 GeV. The energy delivered by the hadronic cascade induced by the beam in the device has been measured by the temperature rise of small sampling blocks of uranium located in several different positions inside the device and counting the fissions in thin probe foils of natural uranium. We find typically G ≈ 30 in reasonable agreement with calculations, where G is the ratio of the energy produced in the device to the energy delivered by the beam. This result opens the way to the realisation of the so-called Energy Amplifier, a practical device to produce energy from thorium or depleted uranium targets exposed to an intense high energy proton beam. Results show that the optimal kinetic is ≥ 1 GeV, below which G decreases but is still acceptable in the energy range explored

A three-ton liquid argon time projection chamber

Abstract We have constructed and operated a 3 ton liquid argon time projection chamber for the R&D programme of the ICARUS project. The chamber has been in op

Performance of a three-ton liquid argon time projection chamber

Abstract We have constructed and operated a 3 ton liquid argon time projection chamber as part of the R&D programme for the ICARUS project. We report on the analysis of events from cosmic rays and from radioactive sources collected from June 1991 to June 1993. We have systematically investigated the performance and the physical parameters of the detector. We present here the results obtained from the analysis of the cosmic rays data on the following items: the electron drift velocity, the electron lifetime, the free electron yield, the electron diffusion coefficient, the space resolution and the particle identification capability. The data from radioactive sources are used to study the energy resolution in the MeV range. The in depth understanding of the basic physics aspects of the liquid argon TPC allows us to conclude that such a detector can be built in large sizes and reliably operated over long periods of the time, providing a new instrument for physics experiments.

Detection of energy deposition down to the keV region using liquid xenon scintillation

Abstract A possible method for WIMPs detection using liquid xenon scintillation is discussed [1]. Background from cosmic and radioactive gamma rays at energies down to the keV region can be easily rejected by requiring the presence of proportional scintillation. The results from a basic test are presented and a prototype detector design is proposed.

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

A study of the factors affecting the electron lifetime in ultra-pure liquid argon

As part of the development program for the ICARUS experiment, which consists of a very large time projection chamber (TPC) filled with ultra-pure liquid Ar (LAr), we have carried out tests with different purifier systems, in order to evaluate the performance of the various parts and to improve the purification techniques developed so far. Electron lifetime τ in LAr has been determined with an improved method based on the measurement of the attenuation of a current due to an electron cloud, photoproduced by a laser pulse impinging on a metallic cathode and moving in a small drift chamber filled with the purified LAr. Results of the above-mentioned tests are reported. During these tests, we observed repeatedly and reproducibly an increase of τ that took place over a period of 10 to 20 h after liquefaction. Several tests performed in an attempt to elucidate this effect, suggest that the increase in τ is due to adsorption of electron-attaching impurities on the walls of the stainless steel container, a process governed by thermal diffusion. The electron lifetime monitoring system reported here was used to measure the electric field dependence of τ in purified LAr doped with O2 and CO2, for fields 100 V/cm < E < 800 V/cm: The results for O2 are consistent with published data.

Results from the commissioning of the n_TOF spallation neutron source at CERN

Abstract The new neutron time-of-flight facility (n_TOF) has been built at CERN and is now operational. The facility is intended for the measurement of neutron induced cross-sections of relevance to Accelerator Driven Systems (ADS) and to fundamental physics. Neutrons are produced by spallation of the 20 GeV /c proton beam, delivered by the Proton Synchrotron (PS), on a massive target of pure lead. A measuring station is placed at ≈185 m from the neutron producing target, allowing high-resolution measurements. The facility was successfully commissioned with two campaigns of measurements, in November 2000 and April 2001. The main interest was concentrated in the physical parameters of the installation (neutron fluence and resolution function), along with the target behavior and various safety-related aspects. These measurements confirmed the expectations from Monte Carlo simulations of the facility, thus allowing to initiate the foreseen physics program.

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.