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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Investigation of the Cosmic Rays Flux Anisotropy at High Energies (10{sup 15}–10{sup 17} eV) by Means of Muon Bundles Registered with the Coordinate-Tracking Detector DECOR

First results of the analysis of cosmic ray anisotropy from muon bundles recorded in the coordinate tracking detector DECOR of the Experimental Complex NEVOD during the 2013–2017 measurement series are discussed. Two event samples differing in the multiplicity of muons, selection conditions, and ranges of the zenith and azimuth angles are analyzed. Estimates of the anisotropy parameters of the flux of primary cosmic rays with energies of 10{sup 1}5–10{sup 1}7 eV are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Cosmic Ray Muons of High and Ultrahigh Energies

Muons are the main component of cosmic rays on the Earth’s surface and underground. The energy spectrum and angular distribution of muons in the atmosphere are related both to the mechanisms of their generation and to the basic characteristics of the primary cosmic rays—their energy spectrum and mass composition. Changes in the muon flux underground are determined by muon energy losses, and its measurements allow muon interaction processes to be studied. The history of extensive cosmic-ray muon investigations covers many decades. A retrospective overview of important directions of cosmic ray muon studies is presented, and analysis of the main experiments and results is given. Special attention is paid to the “muon puzzle”, that is, the muon excess increasing with the energy of primary particles, and to possible ways of solving it.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

MEASUREMENTS OF COSMIC-RAY PROTON AND HELIUM SPECTRA FROM THE BESS-POLAR LONG-DURATION BALLOON FLIGHTS OVER ANTARCTICA

The BESS-Polar Collaboration measured the energy spectra of cosmic-ray protons and helium during two long-duration balloon flights over Antarctica in 2004 December and 2007 December at substantially different levels of solar modulation. Proton and helium spectra probe the origin and propagation history of cosmic rays in the galaxy, and are essential to calculations of the expected spectra of cosmic-ray antiprotons, positrons, and electrons from interactions of primary cosmic-ray nuclei with the interstellar gas, and to calculations of atmospheric muons and neutrinos. We report absolute spectra at the top of the atmosphere for cosmic-ray protons in the kinetic energy range 0.2–160 GeV and helium nuclei in the range 0.15–80 GeV/nucleon. The corresponding magnetic-rigidity ranges are 0.6–160 GV for protons and 1.1–160 GV for helium. These spectra are compared to measurements from previous BESS flights and from ATIC-2, PAMELA, and AMS-02. We also report the ratio of the proton and helium fluxes from 1.1 to 160 GV and compare this to the ratios from PAMELA and AMS-02.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

SPECTRAL INTENSITIES OF ANTIPROTONS AND THE NESTED LEAKY-BOX MODEL FOR COSMIC RAYS IN THE GALAXY

In this paper we note that the spectral intensities of antiprotons observed in Galactic cosmic rays in the energy range ∼1–300 GeV by BESS, PAMELA, and AMS instruments display nearly the same spectral shape as that generated by primary cosmic rays through their interaction with matter in the interstellar medium, without any significant modifications. More importantly, a constant residence time of ∼2.3 ± 0.7 million years in the Galactic volume, independent of the energy of cosmic rays, matches the observed intensities. A small additional component of secondary antiprotons in the energy range below 10 GeV, generated in cocoon-like regions surrounding the cosmic-ray sources, seems to be present. We discuss this result in the context of observations of other secondary components such as positrons and boron, and the bounds on anisotropy of cosmic rays. In the nested leaky-box model the spectral intensities of antiprotons and positrons can be interpreted as secondary products of cosmic-ray interactions.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Proton and Helium Spectra from the CREAM-III Flight

Primary cosmic-ray elemental spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment since 2004. The third CREAM payload (CREAM-III) flew for 29 days during the 2007–2008 Antarctic season. Energies of incident particles above 1 TeV are measured with a calorimeter. Individual elements are clearly separated with a charge resolution of ∼0.12 e (in charge units) and ∼0.14 e for protons and helium nuclei, respectively, using two layers of silicon charge detectors. The measured proton and helium energy spectra at the top of the atmosphere are harder than other existing measurements at a few tens of GeV. The relative abundance of protons to helium nuclei is 9.53 ± 0.03 for the range of 1 TeV/n to 63 TeV/n. This ratio is considerably smaller than other measurements at a few tens of GeV/n. The spectra become softer above ∼20 TeV. However, our statistical uncertainties are large at these energies and more data are needed.

79 ASTRONOMY AND ASTROPHYSICS↗