Development of the ADAMO detector: test with cosmic rays at different zenith angles

ADAMO is a magnetic spectrometer that has been developed to allow a precise measurement of the spectra of the main cosmicnray charged components at ground level. The detector is composed of two main subsystems. The rst is a permanent magnet with a cavity where the magnetic eld is around 0.4 T. The second is a tracking system made of ve double sided silicon micro-strip detecting units with spatial resolutions of and along two orthogonal directions (related to the two sides of the silicon sensors and conventionally referred to as ixi view and iyi view in this work). The whole spectrometer dimensions are ( ) cm ; anyway it allows the measurement of charged particles in the wide range of momenta between about MeV and GeV . During 2003 and 2004 the detector has been modied with respect to its original structure. The acceptance has been increased to allow the study of the rare components of cosmic rays at ground. At present, the magnetic cavity is ( ) mm . A new trigger system has been realized an it is under development to work as a TOF system, the rst step to allow particle discrimination at low momentum. During 2004 a rst set of data was taken at different zenith angles to test the functionality and the performances of the detector. In this work the apparatus and some analysis of these data are presented. ADAMO was presented for the rst time at the 28 ICRC [1], held in Tsukuba (Japan) in 2003. It is a small cosmicnray detector that has been developed for the study at ground level of the main charged components of atmospheric showers (namely muons, protons and electrons) induced by the primary cosmic radiation entering the Earth atmosphere. This project is part of the cosmicnray research activity of the Physics Department and INFN of Florence (Italy) and is managed by a group that is involved in the WiZard Collaboration. The activity of this group is mostly related to the PAMELA satellite experiment, whose launch is scheduled for the end of 2005 on board of the ResursnDK1 Russian satellite. In particular the WiZardnFlorence group has developed the tracking system of the PAMELA detector [2]. The aim of ADAMO is the measurement, for different incoming angles and at different altitudes and geographical locations, of cosmicnray spectra in the wide momentum range between about MeV/ and GeV/ . Measurements in this momentum range are useful to improve the calibrations of the Montecarlo simulations which are used to simulate the atmospheric shower development, especially in relation to the study of the Atmospheric Neutrino Problem. Several muon data exist, which have been collected during the past century, but only in a limited number of cases measurements have been performed in nonnvertical directions and no precise systematic studies exist of the dependencies of ux es by the altitude and the longitude. Moreover only a few measurements exist for the proton component and all of them were done in vertical direction. For these reasons ADAMO could give a contribution to the understanding of the atmospheric shower development, allowing the study in a wide momentum range of the dependencies of cosmicnray spectra at ground level by the latitude, the altitude and the incoming direction.