P. Pistilli

The macro detector at the Gran Sasso Laboratory

Abstract The MACRO detector is presently under construction, its installation at Gran Sasso being planned to start in September 1987. It is a large area detector, the acceptance for isotropic particle fluxes being around 10 000 m 2 sr, designed to search for rare phenomena in the cosmic radiation. It makes use of three detection techniques: liquid scintillator counters, plastic streamer tubes, and track-etch. It will perform a search for GUT monopoles (or any supermassive charged penetrating particle), a survey of cosmic point sources of HE gammas and neutrinos, a systematic study of the penetrating cosmic ray muons, and will be sensitive to neutrino bursts from gravitational stellar collapses in the Galaxy.

Study of penetrating cosmic ray muons and search for large scale anisotropies at the Gran Sasso Laboratory

Abstract The MACRO detector, located in the underground Gran Sasso Laboratory, had its initial data run from February 27 to May 30, 1989, using the first supermodule (SΩ∼800 m 2 sr ) . Approximately 245 000 muon events were recorded. Here are reported the results of the analysis of penetrating muons which determine the measured vertical muon flux at depths greater than 3000 m.w.e. In addition the data have been used to search for large scale anisotropies.

Hadron, electron and muon response of a uranium-scintillator calorimeter

Abstract A hadron calorimeter comprising 10 mm depleted uranium plates and 5 mm plastic scintillator was exposed to electrons, hadrons and muons in the energy range 5–210 GeV. The measured ratios of sampling fractions are 0.8 for e/π and 0.6 for e/mip. The addition of a fine grained electromagnetic calorimeter with 1.6 mm depleted uranium plates and 4 mm plastic scintillator in front of the hadron calorimeter leads to a slightly worse hadronic energy resolution. Results on the longitudinal shower development and energy containment for hadron showers are given.

A Hybrid Experiment to Search for Beauty Particles

We give here a detailed description of experiment WA75, which was performed at CERN to search for beauty particles. Events containing at least one muon with a high momentum transverse to the beam direction were selected; then the primary interactions and decay vertices, located in stacks of nuclear research emulsions, were examined and analysed. The various parts of the apparatus are described and the off-line analysis and search in emulsion are discussed. An estimate is made of the sensitivity of the experiment to beauty- and charmed-particle production.

Experimental study of BB production π-U interactions at 320 GeV energy

Abstract A sample of 29 gu + υ + 35 υ − υ − coming from B B decay have been observed in π -U interactions at 320 GeV energy. The experimental distributions and the total cross section are found to be in good agreement with QCD predictions. The effect of B 0 B 0 mixing is discussed.

Some properties of charmed particles produced in π−-nucleus interactions

Abstract The azimuthal correlation distribution of 102 charmed-particle pairs observed in the hybrid emulsion experiment WA75 is compared with theoretical predictions. The various pairs - (D − D 0 ), (D − D + ), (D 0 D 0 ) and (D + D 0 )-all s how, within statistical error, the same azimuthal correlation distribution, demonstrating its independence from the specific nature of the production channel. Among the decays of 150 charged charmed particles and 138 neutral ones seen, higher multiplicities are favoured for hadronic as opposed to semileptonic decays. The data are consistent with the muonic decays of charged D mesons proceeding through the channels (μ ± , v, K 0 ) and [μ ± , v, K ∗0 (892)] , the fraction through K 0 being 0.76±0.06.

Experimental search for associated gluino production and decay in 350 GeV/cπ− emulsion interactions

Abstract A search for direct evidence of the production and subsequent decay of gluinos has been performed in nuclear emulsions. The emulsion stacks were exposed, as part of a large hybrid apparatus, to a beam of 350GeV/ c π t- mesons, and events were selected on the basis of a “missing-energy” trigger. The missing-energy signature is expected to be a characteristic feature of events in which gluinos are produced and subsequently decay into hadrons and almost non-interacting photinos. The negative result of this search sets an upper limit to the production cross section of light gluinos.

A-dependence of low-mass muon pair production in 300 GeV/c p and 320 GeV/cπ− interactions

Abstract The A-dependence of inclusive μ+μ− production is measured in the kinematical region 2mμ⩽m(μ+μ−) ⪅1.5 GeV/c2, 0.1≲xF(μ+μ−) ≲0.6, using a 300 GeV/cp beam and a 320 GeV/cπ− beam, on Al, Fe, and U targets. Assuming that the production cross section varies as Aα, we obtain α=0.68±0.03−0.05+0.02 for the beam and α=0.8+-0.02−0.05+0.02 for the the π− beam.

Status report of the macro experiment at gran sasso

Abstract The half of the MACRO detector, a large area Monopole, Astrophysics, Cosmic Ray Observatory is nearly completed in Hall B of the Gran Sasso Laboratory. One supermodule is already taken data and the remainder will be activated in few months. A general overview of the MACRO detector, together with its physics capabilities as far as the search for point sources of high energy neutrino is concerned, will be presented.