49 research outputs found
Measuring the prompt atmospheric neutrino flux with down-going muons in neutrino telescopes
In the TeV energy region and above, the uncertainty in the level of prompt
atmospheric neutrinos would limit the search for diffuse astrophysical
neutrinos. We suggest that neutrino telescopes may provide an empirical
determination of the flux of prompt atmospheric electron and muon neutrinos by
measuring the flux of prompt down-going muons. Our suggestion is based on the
consideration that prompt neutrino and prompt muon fluxes at sea level are
almost identical.Comment: 4 pages, 3 figure
From AMANDA to IceCube
The first string of the neoteric high energy neutrino telescope IceCube
successfully began operating in January 2005. It is anticipated that upon
completion the new detector will vastly increase the sensitivity and extend the
reach of AMANDA to higher energies. A discussion of the IceCube's discovery
potential for extra-terrestrial neutrinos, together with the prospects of new
physics derived from the ongoing AMANDA research will be the focus of this
paper. Preliminary results of the first antarctic high energy neutrino
telescope AMANDA searching in the muon neutrino channel for localized and
diffuse excess of extra-terrestrial neutrinos will be reviewed using data
collected between 2000 and 2003. Neutrino flux limits obtained with the
all-flavor dedicated UHE and cascade analyses will be described. A first
neutrino spectrum above one TeV in agreement with atmospheric neutrino flux
expectations and no extra-terrestrial contribution will be presented, followed
by a discussion of a limit for neutralino CDM candidates annihilating in the
center of the Sun.Comment: 15 pages, 8 figures Invited talk contribution at 5th International
Conference on Non-accelerator New Physics (NANP 05), Dubna, Russia, 20-25 Jun
200
Prompt muon contribution to the flux underwater
We present high energy spectra and zenith-angle distributions of the
atmospheric muons computed for the depths of the locations of the underwater
neutrino telescopes. We compare the calculations with the data obtained in the
Baikal and the AMANDA muon experiments. The prompt muon contribution to the
muon flux underwater due to recent perturbative QCD-based models of the charm
production is expected to be observable at depths of the large underwater
neutrino telescopes. This appears to be probable even at rather shallow depths
(1-2 km), provided that the energy threshold for muon detection is raised above
TeV.Comment: 7 pages, RevTeX, 7 eps figures, final version to be published in
Phys.Rev.D; a few changes made in the text and the figures, an approximation
formula for muon spectra at the sea level, the muon zenith-angle distribution
table data and references adde
Gas phase potassium release from a single particle of biomass during high temperature combustion
A notable characteristic of solid biomass fuels as compared to coal is their significantly higher potassium content. Potassium influences ash deposition and corrosion mechanisms in furnaces and boilers, the effects of which may differ depending on phase transformations of potassium species in the gas phase and condensed phase. An understanding of how potassium is released from biomass fuels during the combustion process is therefore useful for plant designers and operators assessing means of avoiding or mitigating these potential problems. An experimental method is used to measure release patterns from single particles of biomass fuels using flame emission spectroscopy and a single-particle combustion rig. The experimental arrangement also allowed simultaneous thermal imaging of the combusting particle in order to determine the surface temperature. A model of the single particle combustion is presented. Using experimental data on devolatilisation and burnout times for different sized particles and the measured surface temperature profiles, the thermal and kinetic sub-models are verified. A model for potassium release is described and this is integrated to the single particle combustion model to allow prediction of the temporal patterns of release of gas-phase potassium. The modelled release patterns were compared with those observed. Good agreement between modelled and measured potassium release patterns was attained confirming that the proposed mechanisms affecting potassium release are valid
BAIKAL experiment: status report
We review the present status of the Baikal Neutrino Project and present the
results obtained with the deep underwater neutrino telescope NT-200.Comment: 4 pages, 3 figures. Presented at TAUP 2001 (7th international
workshop on Topics in Astroparticle and Underground Physics), Sep. 2001,
Laboratori Nazionali del Gran Sasso, Assergi, Ital
High Energy Neutrino Production by Cosmic Ray Interactions in the Sun
The flux of neutrinos originating from cosmic ray interactions with matter in
the Sun has been calculated based on Monte Carlo models for high energy
particle interactions. The resulting flux at the Earth (within the Sun's solid
angle) is higher than the corresponding one from cosmic ray interactions with
the Earth atmosphere. The smallness of the absolute rate, however, precludes it
as a practical `standard candle' for neutrino telescopes and limits neutrino
oscillation searches. On the other hand, it facilitates dark matter searches
based on neutrinos from neutralino annihilation in the Sun.Comment: 14 pages, also available at http://www3.tsl.uu.se/thep/papers
Lepton Fluxes from Atmospheric Charm
We reexamine the charm contribution to atmospheric lepton fluxes in the
context of perturbative QCD. We include next-to-leading order corrections and
discuss theoretical uncertainties due to the extrapolations of the gluon
distributions at small-x. We show that the charm contribution to the
atmospheric muon flux becomes dominant over the conventional contribution from
pion and kaon decays at energies of about 10^5 GeV. We compare our fluxes with
previous calculations.Comment: 19 pages, latex, revtex, psfi
Shower Power: Isolating the Prompt Atmospheric Neutrino Flux Using Electron Neutrinos
At high energies, the very steep decrease of the conventional atmospheric
component of the neutrino spectrum should allow the emergence of even small and
isotropic components of the total spectrum, indicative of new physics, provided
that they are less steeply decreasing, as generically expected. One candidate
is the prompt atmospheric neutrino flux, a probe of cosmic ray composition in
the region of the knee as well as small- QCD, below the reach of collider
experiments. A second is the diffuse extragalactic background due to distant
and unresolved AGNs and GRBs, a key test of the nature of the highest-energy
sources in the universe. Separating these new physics components from the
conventional atmospheric neutrino flux, as well as from each other, will be
very challenging. We show that the charged-current {\it electron} neutrino
"shower" channel should be particularly effective for isolating the prompt
atmospheric neutrino flux, and that it is more generally an important
complement to the usually-considered charged-current {\it muon} neutrino
"track" channel. These conclusions remain true even for the low prompt
atmospheric neutrino flux predicted in a realistic cosmic ray scenario with
heavy and varying composition across the knee (Candia and Roulet, 2003 JCAP
{\bf 0309}, 005). We also improve the corresponding calculation of the neutrino
flux induced by cosmic ray collisions with the interstellar medium.Comment: 15 pages, 4 figures. Minor modifications, version accepted for
publication in JCA
Pathlength distribution of atmospheric neutrinos
We present the distribution of the production heights of atmsopheric
neutrinos as a function of zenith angle and neutrino energy. The distributions
can be used as the input for evaluation of neutrino propagation under various
hypotheses for neutrino flavor oscillations.Comment: REVTeX file with 5 postscript figure
Propagation of Muons and Taus at High Energies
The photonuclear contribution to charged lepton energy loss has been
re-evaluated taking into account HERA results on real and virtual photon
interactions with nucleons. With large processes incorporated, the
average muon range in rock for muon energies of GeV is reduced by only
5% as compared with the standard treatment. We have calculated the tau energy
loss for energies up to GeV taking into consideration the decay of the
tau. A Monte Carlo evaluation of tau survival probability and range show that
at energies below GeV, depending on the material, only tau decays
are important. At higher energies the tau energy losses are significant,
reducing the survival probability of the tau. We show that the average range
for tau is shorter than its decay length and reduce to 17 km in water for an
incident tau energy of GeV, as compared with its decay length of 49 km
at that energy. In iron, the average tau range is 4.7 km for the same incident
energy.Comment: 25 pages including 8 figure