International Journal of Modern Physics A

The Alpha Magnetic Spectrometer (AMS) is a state of the art detector for the extrater-restrial study of matter, antimatter and missing matter. During the STS-91 precursor flight in may 1998 AMS collected nearly 100 millions of Cosmic Rays on Low Earth Orbit, measuring with high accuracy their composition. We review the results on the flux of proton, electron, positron and helium. Analysis of the under cutoff spectra indicates the existence of a new type of belts of energetic trapped particles characterized by a dominance of positrons versus electrons. AMS is currently being refurbished for a three year mission on the International Space Station where the its sensitivity to rare events will be increased by three to four orders of magnitude.

Precise measurements of high energy hadrons have been performed either on balloon-borne or space-borne experiments. The status of the present measurements on H and He, heavier nuclei, isotopes and antiprotons is separately reported. Implications of precise measurements within the framework of models for production and propagation of galactic cosmic rays is discussed. Near future experiments are expected to improve in a significant manner the collected statistics and the energy range covered by present experiments. The results thus obtained will validate current propagation models and accurately constrain their free parameters.

An accurate measurement of the intensity and energy spectra of Cosmic Ray electrons and positrons represents a major experimental challenge. Long exposure times and excellent particle identification capabilities are needed in order to cope with the low intensity of the electron and positron fluxes and the overwhelming background from protons and nuclei in cosmic rays. The motivations for such an experimental effort will be briefly discussed and the most recent results revieweved together with the perspectives of future experiments.

Substantial fluxes of protons and leptons with energies below the geomagnetic cutoff have been measured by the AMS experiment at altitudes of 370-390 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 protons with the atmosphere (detailed descriptions of the magnetic field atmospheric density, as well as the electromagnetic and nuclear interaction processes) are included in the simulation. The results are presented and compared with the experimental data, indicating good agreement with the observed fluxes. The impact of secondary proton flux on particle production in atmosphere is briefly discussed.

In order to study neutrino oscillation phenomena using atmospheric neutrinos, it is crucially important to calculate their absolute fluxes and spectral shapes accurately. Since production and decay processes of muons are accompanied by neutrino production, observations of atmospheric muons give fundamental information about atmospheric neutrinos. Atmospheric muons have been measured at various sites; from a ground level to a balloon floating altitude. Very precise measurement has been carried out on the ground. Muon growth curves are measured during balloon ascending periods. These data can be used to investigate hadronic interaction models. Investigations of atmospheric muons will improve accuracy of the neutrino calculations. Statistics in the muon measurement during balloon experiments are still insufficient. In order to improve the statistics drastically, dedicated muon experiments are very important.

In this work, I study the propagation of cosmic rays inside the magnetic field of the Earth, at distances d ≤ 500 Km from its surface; at these distances, the geomagnetic field deeply influences the diffusion motion of the particles. I compare the different effects of the interplanetary and of the geomagnetic fields, by also discussing their role inside the cosmic rays transport equation; finally, I present an analytical method to solve such an equation through a factorization technique.

For the first time accurate measurements of electron and positron fluxes in the energy range 0.2 ÷ 10 GeV have been performed with the Alpha Magnetic Spectrometer (AMS) at altitudes of 370 ÷ 390 km in the geographic latitude interval ±51.7°. We focused on the under-cutoff lepton fluxes inside the region of the South Atlantic Anomaly (SAA), defined as region where the local magnetic field B ≤ 0.26 G.

A clear transtion region from stably-trapped flux typical of the lnner Van Allen Belts to quasi-trapped flux typical underneath the Van Allen Belts is observed in the SAA up to energies O(Gev).

The observations strongly support positrons abundance in the Inner Van Allen Belts, both in the stably trapped component and in the quasi-trapped one.

The flux maps as a function of the canonical adiabatic variables L, α_o are presented for the intervval 0.95 < L < 3, 0° < α_o < 90° for electrons (E < 10 GeV) and positrons (E < 3 GeV). The results are compared with existing data at lower energies.

The successful simulation results obtained in the interpretation of the recent AMS measurements of proton, leptons and light nuclei particle flux, are reviewed. A similar success in being met in the analysis of secondary particle flux measured in teh atmosphere (antiprotons, muons) and in underground experiments (neutrinos).

The Earth's trapped radiation belts were discovered at the beginning of the space age and were immediately recognised as a considerable hazard to space missions. Consequently, considerable effort was invested in building models of the trapped proton and electron populatinos, culminating in the NASA AP-8 and AE-8 models which have been the de facto standards since the seventies. The CRRES mission has demonstrated that the trapped radiation environment is much more complex than the static environment described by the old models. Spatial and especially temporal variations were shown to be much more important that previously thought, and to require more complex models than those in use at that time. Such models are now becoming available, but they are limited in spatial or temporal coverage, and no global, dynamic, trapped radiation belt model is forthcoming. It is therefore vital to co-ordinate future modelling efforts in order to develop new standard models.

In this work we present some of the recent results obtained with the satellite missions NINA-1 and NINA-2 and the experiments on board MIR space station Sileye-1 and 2. The aim is the study of the low energy (10 MeV - 2 GeV) cosmic ray component and different periods of the solar cycle and during Solar Energetic Particle events. Other items of physics include the measurement of the secondary cosmic ray component, produced in the interaction with the upper layers of Earth's atmosphere and the evaluation of the absorbed and equivalent doses inside MIR.

Results of study of secondary electrons and positrons in the energy range 15–150 MeV in the earth space-orbit are reviewed.

The experimental data on the chemical composition of galactic cosmic rays (GCR) are analysed in the energy range between ≈ 10 MeV/nucl and ≈ PeV. The lower part of the energy range corresponds to the so-called anomalous cosmic rays (ACR). These particles with low charge values can easily penetrate through the Earth's magnetic field and after charge-exchange with neutrals of the Earth's atmosphere increase their charge states to full stripping. As a result of satellite experiments it was shown, that these secondary particles can become trapped in the geomagnetic field and form a radiation belt. Below a short survery of the experimental results which led to this discovery is given.

Space exploration poses health hazards to the crews of manned missions. Exposure to cosmic radiation and loss of bone density are considered the two most important risk factors for long-term missions. Stochastic risk deriving from cosmic radiation exposure can be estimated by physical dosimeters, using appropriate conversion factors. Recent measurements of space radiation fluence and energy spectra will improve current estimates. Biological dosimetry can be used as a tool to determine the risk directly from biological damage. Chromosomal aberrations in astronauts' peripheral blood lymphocytes have been used as a biomarker of cancer risk. In this paper we will also discuss countermeasures to radiation damage, focusing on the problem of shielding in space.

We review some properties of neutrinos in relation to the dark matter and baryogenesis problems.

The results of calculations of the fluxes of charged particles and atmospheric neutrinos are discussed. Results on charged particles are compared with the AMS measurements.

Calculation of secondary particles produced by the interaction of cosmic rays with the nuclei of Earth's atmosphere pose important requirements to particle production models. Here we summarize the important features of hadronic simulations, stressing the importance of the so called "microscopic" approach, making explicit reference to the case of the FLUKA code. Benchmarks are also presented.

This presentation includes recent developments on massive neutrinos and introductory material. Most discussion stays close to the data (=phenomenology), but it is integrated with some more formal (=theoretical) remarks. The importance of oscillations for supernova neutrinos is emphasized, and the peculiar role of ν_e events in this connection is discussed. A new bound on neutrino mass scale, based on double beta decay bound, is obtained.

I discuss the state of the art in the search for stellar collapse neutrinos and the perspectives of this field. The implications for neutrino physics of a high statistics supernova neutrino burst detection by the network of operating experiments are also reviewed.

We consider the hypothesis that dark matter is made of weakly interacting massive particles (WIMPs) and describe how their pair annihilation in the galactic halo generates exotic cosmic ray fluxes. Features for generic WIMP models are reviewed, pointing out cases in which clear signatures arise. Implications from available and upcoming measurements are discussed.

INTEGRAL¹ is an ESA mission designed to study the γ-ray sky in the 10 keV to 10 MeV energy band. It will build upon previous results and expand our knowledge of the γ-ray astronomy. It is organised as an observatory and thus can be exploited by a wide community.

Gamma-ray astrophysics in the energy range between 30 MeV and 30 GeV is in desperate need of arcminute angular resolution and source monitoring capability. The AGILE Mission planned to be operational in 2004-2006 will be the only space mission entirely dedicated to gamma-ray astrophysics above 30 MeV. The main characteristics of AGILE are the simultaneous X-ray and gamma-ray imaging capability (reaching arcminute resolution) and excellent gamma-ray timing (10-100 microseconds). AGILE scientific program will emphasize a quick response to gamma-ray transients and multiwavelength studies of gamma-ray sources.

The detection potential of AMS for photon sources of different origin is assessed. In particular, galactic and extragalactic point sources detected by previous experiments are examined for their detectability at energies above a few GeV. In addition, gamma ray rates from a potential supersymmetric dark matter halo are estimated using different models. It is argued that the constant survey of the gamma ray sky by AMS with a high angular resolution will be an important complement to similar studies using other present and future instruments.

The results of the MC feasibility study of the AMS-02 Detector cosmic-ray γ and e⁺ spectra measurement capabilities are presented. AMS will be able to provide accurate measurements of the above spectra in a broad energy range (up to hundreds of GeV) with energy resolution of a few percent and angular resolution of 0.01-1°. The acceptance of 0.05-0.15 m²sr has been estimated both for e⁺ and γ, with maximal opening angle being 20° to 45°. The systematic study of the background events has been done, the irreducible background to signal ratio below a few percent being obtained.

The direct detection of annihilation products in cosmic rays offers an alternative way to search for supersymmetric dark matter particles candidates. The study of the spectrum of gamma-rays, antiprotons and positrons offers good possibilities to perform this search in a significant portion of the Minimal Supersymmetric Standard Model parameters space. In particular the EGRET team have seen a convincing signal for a strong excess of emission from the galactic center that have not easily explanation with standard processes. We will review the achievable limits with the experiment GLAST taking into accounts the LEP results and we will compare this method with the antiproton and positrons experiments, the direct underground detection and with future experiments at LHC.