Charm production and high energy atmospheric muon and neutrino fluxes

Production of muons and neutrinos in cosmic ray interactions with the atmosphere has been investigated with state-of-the-art Monte Carlo models for hadronic interactions. The resulting conventional muon and neutrino fluxes (from \pi and K decays) agree well with earlier calculations, whereas the improved charm particle treatment used in this study gives significantly lower prompt fluxes compared to earlier estimates. This implies better prospects for detecting very high energy neutrinos from cosmic sources

A Monte Carlo Calculation of Atmospheric Muon and Neutrino Fluxes

Production of muons and neutrinos in cosmic ray interactions with the atmosphere has been investigated with a cascade simulation program based on Lund Monte Carlo programs. The resulting `conventional' muon and neutrino fluxes (from $\pi ,K$ decays) agree well with earlier calculations, whereas the improved charm particle treatment used in this study gives significantly lower `prompt' fluxes compared to earlier estimates. This implies better prospects for detecting very high energy neutrinos from cosmic sources.Comment: 4 pages, uuencoded and gziped ps-fil

Prompt atmospheric neutrinos and muons: dependence on the gluon distribution function

We compute the next-to-leading order QCD predictions for the vertical flux of atmospheric muons and neutrinos from decays of charmed particles, for different PDF's (MRS-R1, MRS-R2, CTEQ-4M and MRST) and different extrapolations of these at small partonic momentum fraction x. We find that the predicted fluxes vary up to almost two orders of magnitude at the largest energies studied, depending on the chosen extrapolation of the PDF's. We show that the spectral index of the atmospheric leptonic fluxes depends linearly on the slope of the gluon distribution function at very small x. This suggests the possibility of obtaining some bounds on this slope in ``neutrino telescopes'', at values of x not reachable at colliders, provided the spectral index of atmospheric leptonic fluxes could be determined.Comment: 20 pages including 8 figure

Measurement of the gluon PDF at small x with neutrino telescopes

We analyze the possibility that neutrino telescopes may provide an experimental determination of the slope lambda of the gluon distribution in the proton at momentum fractions x smaller than the accelerator reach. The method is based on a linear relation between lambda and the spectral index (slope) of the down-going atmospheric muon flux above 100 TeV, for which there is no background. Considering the uncertainties in the charm production cross section and in the cosmic ray composition, we estimate the error on the measurement of lambda through this method, excluding the experimental error of the telescopes, to be ~ +/- 0.2Comment: 16 pages with 16 figures - new version, comments added, same results and figure

Influence of in-bed catalysis by ash-coated olivine on tar formation in steam gasification of biomass

The use of catalytic bed materials has become a state-of-the-art solution to control the concentration of tar in fluidized bed biomass steam gasifiers. Ash-coated olivine is commonly applied as bed material, owing to its relatively high catalytic activity towards tar species. However, the mechanisms and conversion pathways influenced by the ash-coated olivine when applied as an in-bed catalyst are still not well understood. The present work aims at proving that the ash-layered olivine prevents the formation of biomass-derived tar at an early stage of their formation. Tests with olivine at different stages of activation and at different temperatures are carried out in the Chalmers 2-4MWth DFB gasifier. Detailed characterization of the tar and light hydrocarbon fractions are presented and discussed in relation to the sources of aromatic species. It is concluded that the ash-coated olivine prevents the formation of aromatic tar species by promoting the steam reforming of early tar precursors. Gas-phase interactions of the early tar precursors and bed material contribute to the tar reduction observed. The results indicate that olivine interferes the cyclization routes involving C2H2 and C3 hydrocarbons

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