82 research outputs found
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. The 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
Status of cosmic-ray antideuteron searches
The precise measurement of cosmic-ray antiparticles serves as important means
for identifying the nature of dark matter. Recent years showed that identifying
the nature of dark matter with cosmic-ray positrons and higher energy
antiprotons is difficult, and has lead to a significantly increased interest in
cosmic-ray antideuteron searches. Antideuterons may also be generated in dark
matter annihilations or decays, offering a potential breakthrough in unexplored
phase space for dark matter. Low-energy antideuterons are an important approach
because the flux from dark matter interactions exceeds the background flux by
more than two orders of magnitude in the low-energy range for a wide variety of
models. This review is based on the "dbar14 - dedicated cosmic-ray antideuteron
workshop", which brought together theorists and experimentalists in the field
to discuss the current status, perspectives, and challenges for cosmic-ray
antideuteron searches and discusses the motivation for antideuteron searches,
the theoretical and experimental uncertainties of antideuteron production and
propagation in our Galaxy, as well as give an experimental cosmic-ray
antideuteron search status update. This report is a condensed summary of the
article "Review of the theoretical and experimental status of dark matter
identification with cosmic-ray antideuteron" (arXiv:1505.07785).Comment: 9 pages, 4 figures, ICRC 2015 proceeding
The GAPS Experiment to Search for Dark Matter using Low-energy Antimatter
The GAPS experiment is designed to carry out a sensitive dark matter search
by measuring low-energy cosmic ray antideuterons and antiprotons. GAPS will
provide a new avenue to access a wide range of dark matter models and masses
that is complementary to direct detection techniques, collider experiments and
other indirect detection techniques. Well-motivated theories beyond the
Standard Model contain viable dark matter candidates which could lead to a
detectable signal of antideuterons resulting from the annihilation or decay of
dark matter particles. The dark matter contribution to the antideuteron flux is
believed to be especially large at low energies (E < 1 GeV), where the
predicted flux from conventional astrophysical sources (i.e. from secondary
interactions of cosmic rays) is very low. The GAPS low-energy antiproton search
will provide stringent constraints on less than 10 GeV dark matter, will
provide the best limits on primordial black hole evaporation on Galactic length
scales, and will explore new discovery space in cosmic ray physics.
Unlike other antimatter search experiments such as BESS and AMS that use
magnetic spectrometers, GAPS detects antideuterons and antiprotons using an
exotic atom technique. This technique, and its unique event topology, will give
GAPS a nearly background-free detection capability that is critical in a
rare-event search. GAPS is designed to carry out its science program using
long-duration balloon flights in Antarctica. A prototype instrument was
successfully flown from Taiki, Japan in 2012. GAPS has now been approved by
NASA to proceed towards the full science instrument, with the possibility of a
first long-duration balloon flight in late 2020. Here we motivate low-energy
cosmic ray antimatter searches and discuss the current status of the GAPS
experiment and the design of the payload.Comment: 8 pags, 3 figures, Proc. 35th International Cosmic Ray Conference
(ICRC 2017), Busan, Kore
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