G. Nicoletti

Experimental Study of Atmospheric Neutrino Flux in the NUSEX Experiment

The fully contained events detected in the NUSEX nucleon stability experiment have been analysed to search for possible anomalies in the fluxes of atmospheric neutrinos. The measured flux of muon neutrinos is in very good agreement with predictions and no anomaly has been found in the ratio between the rate of electron and muon neutrino events.

The NUSEX detector

Abstract We present in this paper the characteristics, trigger system and performance of the NUSEX detector, designed to study nucleon stability, running in the Mt. Blanc laboratory.

Performance of a limited streamer tube hadron calorimeter

The energy response and the resolution of a hadron calorimeter test module prepared by the ALEPH collaboration at LEP have been studied between 5 and 50 GeV. The energy resolution for pions follows a 0.78√E law for orthogonally incident particles. Effects of different incident polar angles (θ = 90°, 60°, 50°) are studied. The wire readout and the trigger capability are also discussed.

Operation of limited streamer tubes with the gas mixture Ar + CO2 + n-pentane

The active detectors of the ALEPH hadron calorimeter at LEP consist of plastic streamer tubes developed in Frascati. The standard gas mixture for the operation of such devices is argon-isobutane (3070). However, in underground experiments, for safety reasons, one has to reduce the hydrocarbon content. Therefore a study of the behaviour of streamer tubes operated with a Ar/CO2/n-pentane mixture has been performed. The influence of gas composition on efficiency, charge distribution and stability of operation has been investigated, and the results of these tests are presented.

Pion muon identification in the aleph test hadron calorimeter using discriminant analysis

Abstract This paper illustrates a method for the discrimination between πs and μs through the energy measurement and tracking capability of a hadron calorimeter followed by a system of chambers. Data taken in a test run with π and μ beams have been analyzed and compared with a sample indicated as π + μ. These π + μ events are obtained off line by taking one muon and one pion, superimposing their digital patterns and summing up their energy releases. The discriminant analysis employed provides a level of identification of about 99.5%. Such a result is very close to the physical limit corresponding to events with sail-through pions.

An experimental study of the neutrino background in underground experiments on nucleon decay

Abstract In order to investigate experimentally the background induced by atmospheric neutrinos in nucleon decay experiments we have simulated very closely the expected spectrum by means of an accelerator produced neutrino beam and exposed to it a test module of a fine train calorimeter. Two runs have been performed with the detector axis placed at 0° and 45° with respect to the neutrino beam direction, and a total of 400 events have been detected and measured. The background induced by atmospheric neutrinos into various nucleon decay channels has been deduced from these data. These results can be applied to the present or planned nucleon decay experiments.

Hadron showers in an iron-streamer tube sampling calorimeter

Abstract Hadronic showers in an iron-streamer tube sampling calorimeter have been studied for energies ranging between 3 and 25 GeV. Longitudinal and transverse energy distributions have been parametrized and compared with those determined for iron-scintillator calorimeters.

Operation of limited streamer tubes with low hydrocarbon content gas mixtures using neon as noble gas

Abstract The use of neon instead of argon in low hydrocarbon content gas mixtures for streamer tubes is investigated. The role of neon in the streamer development mechanism and the advantages of this choice on the performance of the streamer tubes are discussed.

A study of low hydrocarbon content gas mixtures for streamer tubes

Abstract Several gas mixtures have been tested in order to reduce the hydrocarbon content for the operation of 1 × 1 cm 2 streamer tubes for the Aleph hadron calorimeter. It has been found that the use of n -hexane in place of n -pentane allows a safer operation of streamer tubes at reduced fractions of hydrocarbon. The use of nonflammable gas mixtures is discussed.