Antiproton Excess Research Articles

Antiproton production of propagating cosmic rays under distributed reacceleration

view Abstract Citations (7) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Antiproton Production of Propagating Cosmic Rays under Distributed Reacceleration Simon, Manfred ; Heinbach, U. ; Koch, Ch. Abstract The available measurements on the cosmic-ray antiproton/proton ratio show an excess of antiprotons above predictions derived in the framework of the standard picture of cosmic-ray origin and propagation. Calculations are performed of the production from collisions of cosmic rays with the interstellar gas under the condition of distributed reacceleration. It could be shown that the calculated antiproton/proton ratio is enhanced compared to that derived from the 'leaky box' model, but it remains difficult to bring it into agreement with the data by reasonable astrophysical assumptions. Publication: The Astrophysical Journal Pub Date: September 1987 DOI: 10.1086/165587 Bibcode: 1987ApJ...320..699S Keywords: Antiprotons; Cosmic Rays; Particle Acceleration; Particle Production; Abundance; Monte Carlo Method; Space Radiation; COSMIC RAYS: ABUNDANCES; COSMIC RAYS: GENERAL; PARTICLE ACCELERATION full text sources ADS |

He-3 in galactic cosmic rays

Cosmic-ray ^3He/^4He observations, including a new measurement at ~65 MeV per nucleon from ISEE 3, are compared with interstellar propagation and solar modulation calculations in an effort to understand the origin of cosmic-ray He nuclei. We survey spacecraft and balloon observations of the ^3He/^4He ratio and find improved consistency among measurements in the ~50-300 MeV per nucleon energy range when a previously neglected contribution from atmospheric secondary ^3He is taken into account. These low-energy observations imply a mean escape length of 6-8 g cm ^(-2) in the standard leaky box model for cosmic-ray propagation in the galaxy, a value consistent with that derived from studies of heavier nuclei. Thus, we find no evidence for an excess of low-energy ^3He such as that reported at higher energies. Recent propagation models designed to explain the excess of cosmic-ray antiprotons observed at GeV energies also predict an excess of ^3He that is not observed at low energies.

The case for antiparticles in the extragalactic cosmic radiation

The presence of an excess of low energy antiprotons in the primary cosmic radiation has given rise to a number of possible explanations. The possibility that these are extragalactic in origin is considered and it is shown that there are interesting implications for the bulk of the cosmic radiation at higher energies. In particular, it may be possible to account for a previously puzzling feature, a bump in the cosmic ray energy spectrum in the energy range 10(14) to 10(15) eV, with this primary extragalactic origin hypothesis. A method for testing this hypothesis experimentally is also described.