1,794,463 research outputs found
Secondary atmospheric tau neutrino production
We evaluate the flux of tau neutrinos produced from the decay of pair
produced taus from incident muons using a cascade equation analysis. To solve
the cascade equations, our numerical result for the tau production moment
is given. Our results for the flux of tau neutrinos produced from incident
muons are compared to the flux of tau neutrinos produced via oscillations and
the direct prompt atmospheric tau neutrino flux. Results are given for both
downward and upward going neutrinos fluxes and higher zenith angles are
discussed. We conclude that the direct prompt atmospheric tau neutrino flux
dominates these other atmospheric sources of tau neutrinos for neutrino
energies larger than a few TeV for upward fluxes, and over a wider range of
energy for downward fluxes.Comment: 4 pages, 2 figure
Secondary antiproton production in relativistic plasmas
The possibility is investigated that the reported excess low energy antiproton component of the cosmic radiation results from proton-proton (p-p) interactions in relativistic plasmas. Because of both target and projectile motion in such plasmas, the antiproton production threshold in the frame of the plasma is much lower than the threshold of antiproton production in cosmic ray interactions with ambient matter. The spectrum of the resultant antiprotons therefore extends to much lower energy than in the cosmic ray case. The antiproton spectrum is calculated for relativistic thermal plasmas and the spectrum is estimated for relativistic nonthermal plasmas. As possible production sites, matter accreting onto compact objects located in the galaxy is considered. Possible overproduction of gamma rays from associated neutral pion production can be avoided if the site is optically thick to the photons but not to the antiprotons. A possible scenario involves a sufficiently large photon density that the neutral pion gamma rays are absorbed by photon-photon pair production. Escape of the antiprotons to the interstellar medium can be mediated by antineutron production
Charmonium Production from the Secondary Collisions at LHC Energy
We consider the charmonium production in thermalized hadronic medium created
in ultrarelativistic heavy ion collisions at LHC energy.
The calculations for the secondary and production by annihilation are performed within a kinetic model taking into account the
space-time evolution of a longitudinally and transversely expanding medium. We
show that the secondary charmonium production appears almost entirely during
the mixed phase and it is very sensitive to the charmonium dissociation cross
section with co-moving hadrons. Within the most likely scenario for the
dissociation cross section of the mesons their regeneration in the
hadronic medium will be negligible. The secondary production of mesons
however, due to their large cross section above the threshold, can
substantially exceed the primary yield.Comment: ps file 11
The role of secondary Reggeons in central meson production
We estimate the contribution of f_2 trajectory exchange to the central \eta
and \eta^\prime production. It is shown that secondary Reggeons may give a
large contribution to processes of double diffractive meson production at high
energy.Comment: 7 pages, Latex, 5 figure
and production in collisions and the cosmic-ray flux ratio
Secondary astrophysical production of and cosmic rays is
considered. Inclusive , , and production cross sections in
collisions at large are parametrised using recent experimental
data at LHC energies. The astrophysical production rate ratio
is calculated for an input cosmic ray proton flux
consistent with local measurements. At GeV the cosmic ray flux
ratio measured by AMS02 falls below the production rate
ratio by about 50\%, while at high energy GeV the measured flux
ratio coincides with the production rate ratio of the secondary source.Comment: 9 pages, 8 figure
Cosmic-ray propagation with DRAGON2: II. Nuclear interactions with the interstellar gas
Understanding the isotopic composition of cosmic rays (CRs) observed near
Earth represents a milestone towards the identification of their origin. Local
fluxes contain all the known stable and long-lived isotopes, reflecting the
complex history of primaries and secondaries as they traverse the interstellar
medium. For that reason, a numerical code which aims at describing the CR
transport in the Galaxy must unavoidably rely on accurate modelling of the
production of secondary particles. In this work we provide a detailed
description of the nuclear cross sections and decay network as implemented in
the forthcoming release of the galactic propagation code DRAGON2. We present
the secondary production models implemented in the code and we apply the
different prescriptions to compute quantities of interest to interpret local CR
fluxes (e.g., nuclear fragmentation timescales, secondary and tertiary source
terms). In particular, we develop a nuclear secondary production model aimed at
accurately computing the light secondary fluxes (namely: Li, Be, B) above 1
GeV/n. This result is achieved by fitting existing empirical or semi-empirical
formalisms to a large sample of measurements in the energy range 100 MeV/n to
100 GeV/n and by considering the contribution of the most relevant decaying
isotopes up to iron. Concerning secondary antiparticles (positrons and
antiprotons), we describe a collection of models taken from the literature, and
provide a detailed quantitative comparison.Comment: 22 pages, 12 figure
Regional variability in the trophic requirements of shelf sea fisheries in the Northeast Atlantic, 1973-2000
Hydrographic, plankton, benthos, fisheries landings, and fish diet data from shelf sea areas in the Northeast Atlantic have been combined into an analysis of the foodweb structure and secondary production requirements of regional fisheries. Fish landings from the Baltic and North Sea are shown to be taken from a lower trophic level and are shown to be overall more planktivorous than those from shelf edge regions. The secondary production required per unit of landed fish from the North Sea was approximately half that for landings from the southwest approaches to the UK, referred to as the Celtic Seas, where zooplankton production accounted for only a small fraction of the secondary production demands of the fisheries. In the North Sea, variability in zooplankton production seems to have exerted a bottom-up effect on fish production, which in turn has exerted a top-down effect on the benthos. Conversely, Celtic Seas benthos production has been a bottom-up driver of fish production, which seems to have been independent of variability in plankton production.Thus, climate and fishing pressures can be expected to influence these regional fisheries in very different ways. Overall, the results indicate very strong spatial patterns in the fish foodweb structure and function, which will be important considerations in the establishment of regional management plans for fisheries
The POPOP4 library and codes for preparing secondary gamma-ray production cross sections
The POPOP4 code for converting secondary gamma ray yield data to multigroup secondary gamma ray production cross sections and the POPOP4 library of secondary gamma ray yield data are described. Recent results of the testing of uranium and iron data sets from the POPOP4 library are given. The data sets were tested by comparing calculated secondary gamma ray pulse height spectra measured at the ORNL TSR-II reactor
Hadronic interactions of primary cosmic rays with the FLUKA code
The measured fluxes of secondary particles produced by the interactions of
cosmic rays with the astronomical environment represent a powerful tool to
infer some properties of primary cosmic rays. In this work we investigate the
production of secondary particles in inelastic hadronic interactions between
several cosmic rays species of projectiles and different target nuclei of the
interstellar medium. The yields of secondary particles have been calculated
with the FLUKA simulation package, that provides with very good accuracy the
energy distributions of secondary products in a large energy range. An
application to the propagation and production of secondaries in the Galaxy is
presented.Comment: 8 pages, 4 figures; Contribution to the 34th International Cosmic Ray
Conference, July 30 to August 6, The Hague, Netherlands; fixing a typo in the
y-axis label of Fig.
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