M. Ambriola

PAMELA - A Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics

PAMELA is a satellite-borne experiment designed for precision studies of the charged cosmic radiation. The primary scientific goal is the study of the antimatter component of the cosmic radiation (antiprotons, 80 MeV - 190 GeV; and positrons, 50 MeV - 270 GeV) in order to search for evidence of dark matter particle annihilations. PAMELA will also search for primordial antinuclei (in particular, anti-helium), and test cosmic-ray propagation models through precise measurements of the antiparticle energy spectrum and studies of light nuclei and their isotopes. Concomitant goals include a study of solar physics and solar modulation during the 24th solar minimum by investigating low energy particles in the cosmic radiation; and a reconstruction of the cosmic ray electron energy spectrum up to several TeV thereby allowing a possible contribution from local sources to be studied. PAMELA is housed on-board the Russian Resurs-DKl satellite, which was launched on June 15th 2006 in an elliptical (350-600 km altitude) orbit with an inclination of 70 degrees. PAMELA consists of a permanent magnet spectrometer, to provide rigidity and charge sign information; a Time-of-Flight and trigger system, for velocity and charge determination; a silicon-tungsten calorimeter, for lepton/hadron discrimination; and a neutron detector. An anticoincidence system is used offline to reject false triggers. In this article the PAMELA experiment and its status are reviewed. A preliminary discussion of data recorded in-orbit is also presented.

The Cosmic-Ray Antiproton Flux between 3 and 49 GeV

We report on a new measurement of the cosmic ray antiproton spectrum. The data were collected by the balloon-borne experiment CAPRICE98 which was flown on 28-29 May 1998 from Fort Sumner, New Mexico, USA. The experiment used the NMSU-WIZARD/CAPRICE98 balloon-borne magnet spectrometer equipped with a gas Ring Imaging Cherenkov (RICH) detector, a time-of-flight system, a tracking device consisting of drift chambers and a superconducting magnet and a silicon-tungsten calorimeter. The RICH detector was the first ever flown capable of mass-resolving charge-one particles at energies above 5 GeV. A total of 31 antiprotons with rigidities between 4 and 50 GV at the spectrometer were identified with small backgrounds from other particles. The absolute antiproton energy spectrum was determined in the kinetic energy region at the top of the atmosphere between 3.2 and 49.1 GeV. We found that the observed antiproton spectrum and the antiproton-to-proton ratio are consistent with a pure secondary origin. However, a primary component may not be excluded.We report on a new measurement of the cosmic ray antiproton spectrum. The data were collected by the balloon-borne experiment CAPRICE98, which was —own on 1998 May 28¨29 from Fort Sumner, New Mexico. The experiment used the NMSU-WiZard/CAPRICE98 balloon-borne magnet spectrometer equipped with a gas Ring Imaging Cherenkov (RICH) detector, a time-of-—ight system, a tracking device consisting of drift chambers and a superconducting magnet, and a silicon-tungsten calorimeter. The RICH detector was the —rst ever —own capable of mass-resolving charge-one particles at energies above 5 GeV. A total of 31 antiprotons with rigidities between 4 and 50 GV at the spectrometer were identi—ed with small backgrounds from other particles. The absolute antiproton energy spectrum was determined in the kinetic energy region at the top of the atmosphere between 3.2 and 49.1 GeV. We found that the observed antiproton spectrum and the antiproton-to-proton ratio are consistent with a pure secondary origin. However, a primary component may not be excluded.

The cosmic-ray proton and helium spectra measured with the CAPRICE98 balloon experiment

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 � 1 . 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

The PAMELA experiment on satellite and its capability in cosmic rays measurements.

The PAMELA equipment will be assembled in 2001 and installed on board the Russian satellite Resurs. PAMELA is conceived mainly to study the antiproton and positron fluxes in cosmic rays up to high ...

The PAMELA experiment in space

We provide in this paper a status report of the space experiment PAMELA. PAMELA aims primarily to measure the flux of antiparticles, namely antiprotons and positrons, in cosmic rays with unpreceden ...

Measurements of cosmic-ray electrons and positrons by the Wizard/CAPRICE collaboration

Two recent balloon-borne experiments have been performed by the Wizard/CAPRICE collaboration in order to study the electron and positron components in the cosmic radiation. On 1994 August 8-9 the CAPRICE94 experiment flew from norther Canada and on 1998 May 28-29 the CAPRICE98 experiment flew from New Mexico, USA at altitude8 corresponding to 3.9 and 5.5 g/cm2 of average residual atmosphere respectively. The apparatus were equipped with a Ring Imaging Cherenkov (RICH) detector, a time-of-flight system, a superconducting magnet spectrometer with a tracking system and a 7-radiation-length silicon-tungsten imaging calorimeter. The RICH used in 1994 had a solid NaF radiator while in 1998 the RICH had a CbFlO gaseous radiator. We report on the electron and positron spectra and positron fraction at the top of the atmosphere from few hundred MeV to 40 GeV measured by these two experiments.

In-Orbit Performance of the Space Telescope NINA and Galactic Cosmic-Ray Flux Measurements

The NINA apparatus, on board the Russian satellite Resurs-01 No. 4, has been in polar orbit since 1998 July 10, at an altitude of 840 km. Its main scienti—c task is to study the Galactic, solar, and anomalous components of cosmic rays in the energy interval 10¨200 MeV nucleon~1. 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.

First Mass-resolved Measurement of High-Energy Cosmic-Ray Antiprotons.

We report new results for the cosmic-ray antiproton-to-proton ratio from 3 to 50 GeV at the top of the atmosphere. These results represent the first measurements, on an event-by-event basis, of mass-resolved antiprotons above 18 GeV. The results were obtained with the NMSU-WIZARD/CAPRICE98 balloon-borne magnet spectrometer equipped with a gas-RICH (Ring-Imaging Cerenkov) counter and a silicon-tungsten imaging calorimeter. The RICH detector was the first ever flown that is capable of identifying charge-one particles at energies above 5 GeV. The spectrometer was flown on 1998 May 28-29 from Fort Sumner, New Mexico. The measured p&d1;/p ratio is in agreement with a pure secondary interstellar production.

High-energy deuteron measurement with the CAPRICE98 experiment

We report the first measurement of the deuterium abundance in cosmic rays above 10 GeV nucleon � 1 of kinetic energy. The data were collected by the balloon-borne experiment CAPRICE98, which was flown on 1998 May 28–29 from Fort Sumner, New Mexico. The detector configuration included the NMSU-WiZard/CAPRICE superconducting magnet spectrometer equipped with a gas RICH detector, a silicon-tungsten calorimeter, and a time-of-flight system. By combining the information from the spectrometer and the RICH detector, it was possible to separate deuterons from protons in the kinetic energy range from 12 to 22 GeV nucleon � 1 .I n order to estimate the proton background and the deuteron selection efficiency, we developed an empirical model for the response of the instrument, based on the data collected in this experiment. The analysis procedure is described in this paper, and the result on the absolute flux of deuterium is presented. We found that the deuterium abundance at high energy is consistent with the hypothesis that the propagation mechanism of light nuclei is the same as that of heavier secondary components. Subject headings: balloons — cosmic rays — Galaxy: abundances — ISM: abundances

About Separation of Hadron and Electromagnetic Cascades in the Pamela Calorimeter

Results of calibration of the PAMELA instrument at the CERN facilities are discussed. In September, 2003, the calibration of the Neutron Detector together with the Calorimeter was performed with th ...