Abstract
The satellite-borne PAMELA experiment is aimed at precision measurements of the charged light component of the cosmic-ray spectrum, with a particular focus on antimatter. It consists of a magnetic spectrometer, a time-of-flight system, an electromagnetic calorimeter with a tail catcher scintillating layer, an anticoincidence system and a neutron detector. PAMELA has measured the absolute fluxes of boron and carbon and the B/C ratio, which plays a central role in galactic propagation studies in order to derive the injection spectra at sources from measurements at Earth. In this paper, the data analysis techniques and the final results are presented.
Highlights
During the propagation in the interstellar medium (ISM) from the acceleration sites to Earth, galactic cosmic rays undergo various physical processes which shape the injection spectra and chemical compositions down to the measured ones at Earth
The boron and carbon fluxes and the boron-over-carbon (B/C) ratio measured by PAMELA as functions of kinetic energy per nucleon are shown in fig. 2
A very simple fit of PAMELA data based on the GALPROP transport code [11] gives a slope of the diffusion coefficient of 0.397±0.007, not allowing to discriminate between Kolmogorov and a Kraichnan diffusion types
Summary
During the propagation in the interstellar medium (ISM) from the acceleration sites to Earth, galactic cosmic rays undergo various physical processes which shape the injection spectra and chemical compositions down to the measured ones at Earth. An effect of this optimization is that the front-end readout electronics of the tracking system saturates when a high-Z particle like a boron or carbon nuclei crosses a silicon layer of the spectrometer releasing a high quantity of energy via ionization.
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