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Title: Positron fraction in cosmic rays and models of cosmic-ray propagation

Abstract

The positron fraction observed by PAMELA and other experiments up to {approx}100 GeV is analyzed in terms of models of cosmic-ray propagation. It is shown that generically we expect the positron fraction to reach {approx}0.6 at energies of several TeV, and its energy dependence bears an intimate but subtle connection with that of the boron to carbon ratio in cosmic rays. The observed positron fraction can be fit in a model that assumes a significant fraction of the boron below {approx}10 GeV is generated through spallation of cosmic-ray nuclei in a cocoonlike region surrounding the sources, and the positrons of energy higher than a few GeV are almost exclusively generated through cosmic-ray interactions in the general interstellar medium. Such a model is consistent with the bounds on cosmic-ray anisotropies and other observations.

Authors:
;  [1]
  1. Physics Department and McDonnell Center for the Space Sciences, Washington University, St. Louis, Missouri 63130 (United States)
Publication Date:
OSTI Identifier:
21415212
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 82; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevD.82.023009; (c) 2010 The American Physical Society
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; BORON; CARBON; CONCENTRATION RATIO; COSMIC POSITRONS; COSMIC RADIATION; COSMIC RAY DETECTION; COSMIC RAY PROPAGATION; ENERGY DEPENDENCE; GEV RANGE; INTERACTIONS; INTERSTELLAR SPACE; SPALLATION; TEV RANGE 01-10; ANTILEPTONS; ANTIMATTER; ANTIPARTICLES; DETECTION; DIMENSIONLESS NUMBERS; ELEMENTARY PARTICLES; ELEMENTS; ENERGY RANGE; FERMIONS; IONIZING RADIATIONS; LEPTONS; MATTER; NONMETALS; NUCLEAR REACTIONS; POSITRONS; RADIATION DETECTION; RADIATIONS; SECONDARY COSMIC RADIATION; SEMIMETALS; SPACE; TEV RANGE

Citation Formats

Cowsik, R., and Burch, B. Positron fraction in cosmic rays and models of cosmic-ray propagation. United States: N. p., 2010. Web. doi:10.1103/PHYSREVD.82.023009.
Cowsik, R., & Burch, B. Positron fraction in cosmic rays and models of cosmic-ray propagation. United States. doi:10.1103/PHYSREVD.82.023009.
Cowsik, R., and Burch, B. Thu . "Positron fraction in cosmic rays and models of cosmic-ray propagation". United States. doi:10.1103/PHYSREVD.82.023009.
@article{osti_21415212,
title = {Positron fraction in cosmic rays and models of cosmic-ray propagation},
author = {Cowsik, R. and Burch, B.},
abstractNote = {The positron fraction observed by PAMELA and other experiments up to {approx}100 GeV is analyzed in terms of models of cosmic-ray propagation. It is shown that generically we expect the positron fraction to reach {approx}0.6 at energies of several TeV, and its energy dependence bears an intimate but subtle connection with that of the boron to carbon ratio in cosmic rays. The observed positron fraction can be fit in a model that assumes a significant fraction of the boron below {approx}10 GeV is generated through spallation of cosmic-ray nuclei in a cocoonlike region surrounding the sources, and the positrons of energy higher than a few GeV are almost exclusively generated through cosmic-ray interactions in the general interstellar medium. Such a model is consistent with the bounds on cosmic-ray anisotropies and other observations.},
doi = {10.1103/PHYSREVD.82.023009},
journal = {Physical Review. D, Particles Fields},
number = 2,
volume = 82,
place = {United States},
year = {Thu Jul 15 00:00:00 EDT 2010},
month = {Thu Jul 15 00:00:00 EDT 2010}
}