arXiv subjects
Publications and source records attributed to A. Morselli.
We will describe the prospects for detecting gamma-rays from WIMP's annihilation in the Galactic Center and we compare this search with the possibilities at LHC and with space antimatter experiments like PAMELA.
The PAMELA experiment is a satellite-borne apparatus designed to study charged particles in the cosmic radiation with a particular focus on antiparticles. PAMELA is mounted on the Resurs DK1 satellite that was launched from the Baikonur cosmodrome on June 15th 2006. The PAMELA apparatus comprises a time-of-flight system, a magnetic spectrometer, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail catcher scintillator and a neutron detector. The combination of these devices allows antiparticles to be reliably identified from a large background of other charged particles. This paper reviews the design, space qualification and on-ground performance of PAMELA. The in-orbit performance will be discussed in future publications.
Many different mechanisms can contribute to antiprotons and positrons production, ranging from conventional reactions up to exotic processes like neutralino annihilation. The open problems are so fundamental (i.e.: is the universe symmetric in matter and antimatter ?) that experiments in this field will probably be of the greatest interest in the next years. Here we will summarize the present situation, showing the different hypothesis and models and the experimental measurements needed to lead to a more established scenario.
We studied the variation of $e^+$ and $\bar p$ top of the atmosphere spectra due to the parameters uncertainties of the Milky Way geometry, propagation models and cross sections. We used the B/C data and Galprop code for the propagation analysis. We also derived the uncertainty bands for subFe/Fe ratio, H and He. Finally, we considered a neutralino induced component in the antiproton flux in the mSUGRA framework. PAMELA expectations for positrons and antiprotons are calculated. We studied in details the possibility of disentanglement of an eventual signal component in the antiproton spectra in a clumpy halo scenario: minimal values of clumpiness factors necessary to disentangle the signal from the background without violating the quality of the antiproton data fit are found. There are also given examples of total spectra in comparison with existing experimental data and an example of PAMELA prediction for the total spectra. The main result of this work is that for the diffusion and convection background model PAMELA will be able to disentangle an eventual supersymmetric signal even for small clumpiness factors.
This paper presents the simulation of the GLAST high energy gamma-ray telescope. The simulation package, written in C++, is based on the Geant4 toolkit, and it is integrated into a general framework used to process events. A detailed simulation of the electronic signals inside Silicon detectors has been provided and it is used for the particle tracking, which is handled by a dedicated software. A unique repository for the geometrical description of the detector has been realized using the XML language and a C++ library to access this information has been designed and implemented. A new event display based on the HepRep protocol was implemented. The full simulation was used to simulate a full week of GLAST high energy gamma-ray observations. This paper outlines the contribution developed by the Italian GLAST software group.
We have studied the variation of $e^+$ and $\bar p$ top of the atmosphere spectra due to the parameters uncertainties of the Milky Way geometry, propagation models and cross sections. We have used the B/C data and Galprop code for propagation analysis. We have also derived the uncertainty bands for subFe/Fe ratio, H and He. Finally we have considered a neutralino induced component in the mSUGRA framework. We conclude that even in the case of diffusion convection model for the standard propagation, where secondary spectra gives a good fit of the data, SUSY contribution can not be excluded up to now due to the overall uncertainties.
A new measurement of the primary cosmic-ray proton and helium fluxes from 3 to 350 GeV was carried out by the balloon-borne CAPRICE experiment in 1998. This experimental setup combines different detector techniques and has excellent particle discrimination capabilities allowing clear particle identification. Our experiment has the capability to determine accurately detector selection efficiencies and systematic errors associated with them. Furthermore, it can check for the first time the energy determined by the magnet spectrometer by using the Cherenkov angle measured by the RICH detector well above 20 GeV/n. The analysis of the primary proton and helium components is described here and the results are compared with other recent measurements using other magnet spectrometers. The observed energy spectra at the top of the atmosphere can be represented by (1.27+-0.09)x10^4 E^(-2.75+-0.02) particles (m^2 GeV sr s)^-1, where E is the kinetic energy, for protons between 20 and 350 GeV and (4.8+-0.8)x10^2 E^(-2.67+-0.06) particles (m^2 GeV nucleon^-1 sr s)^-1, where E is the kinetic energy per nucleon, for helium nuclei between 15 and 150 GeV nucleon^-1.
Cosmic ray measurements performed with the instrument SilEye-2 on Mir space station are presented. SilEye-2 is a silicon detector telescope for the study of the causes of Light Flashes perception by astronauts. As a stand-alone device, it monitors in the short and long term the radiation composition inside Mir. The cosmic ray detector consists of an array of 6 active silicon strip detectors which allow nuclear identification of cosmic rays up to Iron. The device was operational for more than 1000 hours in the years 1998-2000, measuring also several Solar Particle Events. In this work we present the in-flight performance of the instrument and nuclear abundance data from Boron to Silicon above ~150 MeV/n inside Mir.
This article reports nine Solar Energetic Particle events detected by the instrument NINA between October 1998 and April 1999. NINA is a silicon-based particle detector mounted on-board the Russian satellite Resurs-01-N4, which has flown at an altitude of about 800 km in polar inclination since July 1998. For every solar event the power-law He4 spectrum across the energy interval 10--50 MeV/n was reconstructed, and spectral indexes, gamma, from 1.8 to 6.8 extracted. Data of He3 and He4 were used to determine the He3/He4 ratio, that for some SEP events indicated an enrichment in He3. For the 1998 November 7 event the ratio reached a maximum value of 0.33+- 0.06, with spectral indexes of gamma = 2.5 +- 0.6 and gamma = 3.7 +- 0.3 for He3 and He4, respectively. The He3/He4 ratio averaged over the remaining events was 0.011 +- 0.004. For all events the deuterium-to-proton ratio was determined. The average value over all events was (3.9+-1.4) 10^{-5} across the energy interval 9--12 MeV/n. For one event (1998 November 24) this ratio yielded approximately 10 times higher than normal coronal values. Upper limits on the H3/H1 counting ratio for all events were determined. For the 1998 November 14 SEP event the high flux of heavy particles detected made it possible to reconstruct the carbon and oxygen flux.
The direct detection of annihilation products in cosmic rays offer an alternative way to search for dark matter particles candidates. Here we will see in particular that the study of the spectrum of antiproton and positrons offer good possibilities to perform this search and we will review our experimental effort in this direction.
SuperAGILE is the X-ray stage of the AGILE gamma-ray mission. It is devoted to monitor X-ray (10-40 keV) sources with a sensitivity better than 10 mCrabs in 50 ks and to detect X-ray transients in a field of view of 1.8 sr, well matched to that of the gamma-ray tracker, with few arc-minutes position resolution and better than 5 us timing resolution. SuperAGILE is designed to exploit one additional layer of four Si microstrip detectors placed on top of the AGILE tracker, and a system of four mutually orthogonal one-dimensional coded masks to encode the X-ray sky. The total geometric area is 1444 cm^2. Low noise electronics based on ASIC technology composes the front-end read out. We present here the instrumental and astrophysical performances of SuperAGILE as derived by analytical calculations, Monte Carlo simulations and experimental tests on a prototype of the silicon microstrip detector and front-end electronics.
The NINA apparatus, on board the Russian satellite Resurs-01 n.4, has been in polar orbit since 1998 July 10, at an altitude of 840 km. Its main scientific task is to study the galactic, solar and anomalous components of cosmic rays in the energy interval 10--200 MeV/n. In this paper we present a description of the instrument and its basic operating modes. Measurements of Galactic Cosmic Ray spectra will also be shown.
We describe the AGILE gamma-ray astronomy satellite which has recently been selected as the first Small Scientific Mission of the Italian Space Agency. With a launch in 2002, AGILE will provide a unique tool for high-energy astrophysics in the 30 MeV - 50 GeV range before GLAST. Despite the much smaller weight and dimensions, the scientific performances of AGILE are comparable to those of EGRET.
The gamma-ray detector AGILE, operating in the energy range from 30 MeV to 50 GeV, is composed by a tracking part, a light calorimeter and an anticoincidence system. Here we describe the detector and its capabilities to determine the arrival direction and energy of the detected photons.