Abstract: "Antiparticles account for a small fraction of
cosmic rays and are known to be produced in interactions between cosmic-ray
nuclei and atoms in the interstellar medium, which is referred to as a
'secondary source'. Positrons might also originate in objects such as
pulsars and microquasars or through dark matter annihilation, which would
be 'primary sources'. Previous statistically limited measurements of the
ratio of positron and electron fluxes have been interpreted as evidence for
a primary source for the positrons, as has an increase in the total
electron+positron flux at energies between 300 and 600 GeV. Here we report
a measurement of the positron fraction in the energy range 1.5-100 GeV. We
find that the positron fraction increases sharply over much of that range,
in a way that appears to be completely inconsistent with secondary sources.
We therefore conclude that a primary source, be it an astrophysical object
or dark matter annihilation, is necessary."
This report, published in April 2009 in Nature, was cited
68 times in current journal article indexed by
Clarivate during September-October 2009. Only two other physics
papers published in the last two years, aside from reviews, attracted
greater numbers of citations during that two-month period. Indeed, in a
tally of papers published in 2009 that were most cited by year's end, this
report ranks at #3. Prior to the most recent bimonthly count, citations to
the paper have accrued as follows:
July-August 2009: 35 citations
May-June 2009: 18 Total
citations to date: 121
SOURCE:
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