E. Mocchiutti

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.

A high granularity imaging calorimeter for cosmic-ray physics

An imaging calorimeter has been designed and is being built for the PAMELA satellite-borne experiment. The physics goals of the experiment are the measurement of the flux of antiprotons, positrons and light isotopes in the cosmic radiation. The calorimeter is designed to perform a precise measurement of the total energy deposited, to reconstruct the spatial development of the showers (both in the longitudinal and in the transverse directions), and to measure the energy distribution along the shower itself. From this information, the calorimeter will identify antiprotons from an electron background and positrons in a background of protons with an efficiency of about 95% and a rejection power better than 10 � 4 . Furthermore, a self-trigger system has been implemented with the calorimeter that will be employed to measure high-energy (from about 300 GeV to more than 1 TeV) electrons. The instrument is composed of 22 layers of tungsten, each sandwiched between two ‘‘views’’ of silicon strip detectors (X and Y ). The signals are read out by a custom VLSI front-end chip, the CR1.4P, specifically designed for the PAMELA calorimeter, with a dynamic range of 7.14 pC or 1400 minimum ionizing particle (mip). We report on the simulated performance and prototype design. r 2002 Elsevier Science B.V. All rights reserved.

Launch of the space experiment PAMELA

Abstract PAMELA is a satellite borne experiment designed to study with great accuracy cosmic rays of galactic, solar, and trapped nature in a wide energy range (protons 80xa0MeV–700xa0GeV, electrons 50xa0MeV–400xa0GeV). Main objective is the study of the antimatter component: antiprotons (80xa0MeV–190xa0GeV), positrons (50xa0MeV–270xa0GeV) and search for antimatter with a precision of the order of 10 −8 . The experiment, housed on board the Russian Resurs-DK1 satellite, was launched on June 15th, 2006 in a 350xa0×xa0600xa0km orbit with an inclination of 70°. The detector is composed of a series of scintillator counters arranged at the extremities of a permanent magnet spectrometer to provide charge, time-of-flight, and rigidity information. Lepton/hadron identification is performed by a silicon–tungsten calorimeter and a neutron detector placed at the bottom of the device. An anticounter system is used offline to reject false triggers coming from the satellite. In self-trigger mode the calorimeter, the neutron detector, and a shower tail catcher are capable of an independent measure of the lepton component up to 2xa0TeV. In this work we describe the experiment, its scientific objectives, and the performance in the first months after launch.

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 ...

The GAMMA-400 experiment: Status and prospects

The development of the GAMMA-400 γ-ray telescope continues. The GAMMA-400 is designed to measure fluxes of γ-rays and the electron-positron cosmic-ray component possibly associated with annihilation or decay of dark matter particles; and to search for and study in detail discrete γ-ray sources, to measure the energy spectra of Galactic and extragalactic diffuse γ-rays, and to study γ-ray bursts and γ-rays from the active Sun. The energy range for measuring γ-rays and electrons (positrons) is from 100 MeV to 3000 GeV. For 100-GeV γ-rays, the γ-ray telescope has an angular resolution of ∼0.01°, an energy resolution of ∼1%, and a proton rejection factor of ∼5 × 105. The GAMMA-400 will be installed onboard the Russian Space Observatory.

Measurements of quasi-trapped electron and positron fluxes with PAMELA

This paper presents precise measurements of the differential energy spectra of quasi-trapped secondary electrons and positrons and their ratio between 80 MeV and 10 GeV in the near-equatorial regio ...

New measurements of the energy spectra of high-energy cosmic-ray protons and helium nuclei with the calorimeter in the PAMELA experiment

New measurements of the energy spectra of cosmic-ray protons and helium nuclei with significantly increased statistics owing to an improvement of the event selection technique and the involvement of all data over the period 2006–2013 in the analysis have been made at energies above 0.8 TeV/nucleon with a position-sensitive calorimeter based on data from the PAMELA satellite-borne experiment.

Measuring fluxes of the protons and helium nuclei of high-energy cosmic rays

Techniques for measuring helium nuclei and proton energy spectra in circumterrestrial space were developed on the basis of simulated data and data from the position-sensitive silicon-tungsten calorimeter in the PAMELA satellite experiment. The thickness of the calorimeter is 0.6 nuclear interaction lengths. In this work, the experimental results for the measured energy spectra of the protons and helium nuclei of cosmic rays with energies above 50 GeV are presented.

Measurement of galactic cosmic-ray deuteron spectrum in the PAMELA experiment

This work presents the results of measuring the deuteron spectrum of Galactic cosmic rays (GCRs) with the PAMELA experiment. The PAMELA is an international experiment. Its main objectives are to search for antimatter and measure proton, helium nuclei, electron, and positron spectra over a wide range of energies. In addition, the experimental setup allows the detection of deuterons and the reconstruction of their spectra at low energies. Cosmic ray deuteron spectrum and the deuteron-proton ratio measured in the PAMELA experiment in the energy range of 50–650 MeV/nucleon are presented below.

Spectra of primary cosmic-ray positrons and electrons in the PAMELA experiment

The PAMELA experiment is being conducted aboard the Russian satellite Resurs-DK 1, which was launched into a near-Earth circumpolar orbit on June 15, 2006. The instrument, which includes a magnetic spectrometer and an electromagnetic calorimeter (16X0), allows us to measure the fluxes of cosmic-ray electrons and positrons over a wide range of energies from ∼100 MeV to hundreds of GeV. This work presents the measurement data collected from July 2006 through January 2010 on the spectra of primary cosmic-ray electrons and positrons. At low energies, this spectrum is in good agreement with a diffusion model that includes reacceleration and damping. At high energies, the measured spectrum is harder than the one predicted.