Properties of Cosmic Helium Isotopes Measured by the Alpha Magnetic Spectrometer.
Journal
Physical review letters
ISSN: 1079-7114
Titre abrégé: Phys Rev Lett
Pays: United States
ID NLM: 0401141
Informations de publication
Date de publication:
01 Nov 2019
01 Nov 2019
Historique:
revised:
02
10
2019
received:
02
08
2019
entrez:
26
11
2019
pubmed:
26
11
2019
medline:
26
11
2019
Statut:
ppublish
Résumé
Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of ^{3}He and ^{4}He fluxes are presented. The measurements are based on 100 million ^{4}He nuclei in the rigidity range from 2.1 to 21 GV and 18 million ^{3}He from 1.9 to 15 GV collected from May 2011 to November 2017. We observed that the ^{3}He and ^{4}He fluxes exhibit nearly identical variations with time. The relative magnitude of the variations decreases with increasing rigidity. The rigidity dependence of the ^{3}He/^{4}He flux ratio is measured for the first time. Below 4 GV, the ^{3}He/^{4}He flux ratio was found to have a significant long-term time dependence. Above 4 GV, the ^{3}He/^{4}He flux ratio was found to be time independent, and its rigidity dependence is well described by a single power law ∝R^{Δ} with Δ=-0.294±0.004. Unexpectedly, this value is in agreement with the B/O and B/C spectral indices at high energies.
Identifiants
pubmed: 31763896
doi: 10.1103/PhysRevLett.123.181102
doi:
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM