G. Tarle

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.

The cosmic-ray He-3/He-4 ratio from 100 to 1600 MeV/amu

The Superconducting Magnet Instrument for Light Isotopes (SMILI) flew for 19 hours on September 1, 1989, with a residual overburden of 5 g/sq cm. It measured the charge, rigidity, and velocity of 30,000 cosmic-ray helium nuclei, with velocity determined by time-of-flight and Cerenkov techniques. Using these data, the flux and isotopic composition of helium as a function of energy were determined. The observed isotopic composition is consistent with that expected from interstellar propagation models inferred from the secondaries of CNO, in contrast to earlier observations which indicated an overabundance of He-3. We discuss constraints that this result places on cosmic-ray transport and solar modulation models.

The first precision drift tube chambers for the ATLAS muon spectrometer

Abstract The muon spectrometer of the ATLAS detector for the Large Hadron Collider is designed to provide a muon transverse momentum resolution of 2%–10% for momenta between 6xa0GeV and 1xa0TeV over a pseudo-rapidity range of | η |⩽2.7. This required the development of precision drift chambers with a track position resolution of 40 μ m, the Monitored Drift Tube (MDT) chambers. We report about the construction of the three main types of MDT chambers for ATLAS, test results and the first production experience.

Performance of the HEAT spectrometer for cosmic ray electrons and positrons

Abstract A new detector system for observations of cosmic ray electrons and positrons has been flown on a high altitude balloon in May 1994. The instrumentation includes a superconducting magnet and a drift tube hodoscope for the measurement of particle rigidities, and a combination of transition radiation detectors, shower counters and a time-of-flight system for particle identification and energy measurement. We will discuss the performance of the individual components and demonstrate that a reliable identification of the rare positron component has been achieved up to 50 GeV.

Characterization and radiation testing of the Harris HS9008RH flash analogue to digital converter

Abstract Results from tests characterizing the performance and radiation hardness of the HS9008RH flash analog to digital convertor (FADC) are presented. These tests were performed primarily to evaluate the suitability of this device for use in the GEM Central Tracker at the SSC experiment. Basic performance characteristics and susceptibility of these characteristics to radiation were examined. Performance test results indicate that the device integral nonlinearity is sampling rate dependent and worsens rapidly above a sampling rate of 15 megasamples per second (MSPS). No degradation in performance of the device was observed after its exposure of up to 81 Mrad of 1.25 MeV γ radiation from a 60 Co source. Exposure of the device to a reactor fast neutron fluence ( E > 100 keV) of 5 × 10 14 /cm 2 resulted in no significant observed performance degradation as well.

Balloon observations of galactic cosmic ray helium before and during a Forbush decrease

The energy spectrum of galactic cosmic ray Helium was measured in two different balloon experiments launched four days apart from Canada: SMILI-I on 1-Sept-1989 and MASS on 5-Sept-1989. A slow Forbush decrease began on 4-Sept-1989 and had not reached its maximum at the time of the MASS flight. Comparison of the balloon measurements shows a fractional decrease of 0.37 to 0.15 in the Helium flux between 200 and 450 MeV/nucleon (1.2–2.0 GV). The rigidity dependence is analyzed in two models and found to be steeper than previous observations. Interplanetary particle data and ground-based Neutron Monitor results are consistent with the balloon observations. Probable sources for this Forbush decrease are discussed.

GRACE: a prototype for the Gran Sasso air Cherenkov experiment

Abstract GRACE is a five element array of air Cherenkov light collectors designed to measure the energy of primary cosmic rays and operate on the terrain over the deep underground muon tracking detector, MACRO, at the Gran Sasso National Laboratory in Italy. The coincidence detection of air Cherenkov photons and deep underground muons produced in extensive air showers will allow an association of the primary energy with the muon events observed underground. We present detailed Monte Carlo calculations of the expected signal, a complete description of our detectors and test results of their initial deployment at the University of Michigan Peach Mountain Observatory.

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.