The Alpha Magnetic Spectrometer (AMS): search for antimatter and dark matter on the International Space Station

The AMS is a state of the art detector for extraterrestrial study of antimatter, matter and missing matter. After a precursor flight on STS91 in May 1998, AMS will be installed on the International Space Station where it will operate for three years. In this paper the AMS experiment is described and is physics potential reviewed.Comment: Invited talk to S. Miniato 1997, to be published on N.I.M., 8 pages 7 figures, LATEX, espcvc2.sty include

Testing diffusion of cosmic rays in the heliosphere with proton and helium data from AMS

After six years of continuous observations in space, the Alpha Magnetic Spectrometer experiment has released new data on the temporal evolution of the proton and helium fluxes in cosmic rays. These data revealed that the ratio between proton and helium fluxes at the same value of rigidity $R=p/Z$ (momentum/charge ratio) is not constant at $R\lesssim$ 3 GV. In particular, the ratio is found to decrease steadily during the descending phase of Solar Cycle 24 toward the next minimum. We show that such a behavior is a remarkable signature of the $\beta\times\lambda(R)$ dependence in the diffusion of cosmic rays in heliosphere, where $\beta$ is their adimensional speed and $\lambda(R)$ is their mean free path, a universal function of rigidity for all nuclei. This dependence is responsible for distinctive charge/mass dependent effects in the time-dependent modulation of low-rigidity particles.Peer Reviewe

Development of a SiPM Cherenkov camera demonstrator for the CTA observatory telescopes

The Cherenkov Telescope Array (CTA) Consortium is developing the new generation of ground observatories for the detection of ultra-high energy gamma rays. The Italian Institute of Nuclear Physics (INFN) is participating to the R&D of a possible solution for the Cherenkov photon cameras based on Silicon Photomultipliers (SiPM) sensitive to UV energies. INFN is developing the concept, mechanics and electronics for SiPM prototype modules intended to equip the focal planes of CTA telescopes. The module design and performances are reviewed here

Characterization and possible astrophysics applications of UV sensitive SiPM devices

The National Institute of Nuclear Physics (INFN) is involved in the R&D of Silicon Photomultiplier (SiPM) sensors optimized to detect near-UV (NUV) photon radiation in low-intensity photons and high-precision time mesaurements, in collaboration with the Bruno Kessler Foundation (FBK). The performances of 6×6 mm2 NUV-HD SiPMs with 30×30 μm2 microcell area and the possible prospects for production and packaging of multi-sensor modules for astrophysical applications are discussed in this paper

Atmospheric production of energetic protons, electrons and positrons observed in near Earth orbit

Abstract Substantial fluxes of protons and leptons with energies below the geomagnetic cutoff have been measured by the AMS experiment at altitudes of 350–390 km, in the latitude interval ±51.7°. The production mechanisms of the observed trapped fluxes are investigated in detail by means of the FLUKA Monte Carlo simulation code. All known processes involved in the interaction of the cosmic rays with the atmosphere (detailed descriptions of the magnetic field and the atmospheric density, as well as the electromagnetic and nuclear interaction processes) are included in the simulation. The results are presented and compared with experimental data, indicating good agreement with the observed fluxes. The impact of the secondary proton flux on particle production in atmosphere is briefly discussed

Protons in near earth orbit

The proton spectrum in the kinetic energy range 0.1 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380 km. Above the geomagnetic cutoff the observed spectrum is parameterized by a power law. Below the geomagnetic cutoff a substantial second spectrum was observed concentrated at equatorial latitudes with a flux ~ 70 m^-2 sec^-1 sr^-1. Most of these second spectrum protons follow a complicated trajectory and originate from a restricted geographic region.Comment: 19 pages, Latex, 7 .eps figure