1,264 research outputs found
High energy astrophysics and high altitude laboratories
These are some summary remarks given at the Chacaltaya meeting on cosmic ray physics, held in La Paz (Bolivia), July 23-27, 2000. The meeting covered a wide range of top ics in cosmic ray p hysics and high energy astrop hysics.
This contribution briefly touches on some of the highlights of the meeting, and discusses the important role that high-altitude laboratories can have in the future of these fundamental fields
Gamma astronomy from space
In this contribution I will review the status of Îł-astronomy at energies larger than ⌠30 MeV from satellites. The measurements of the instruments aboard the Compton Gamma Ray Observatory have given a tremendous boost to this field of research, with Îł-rays observed from a wide range of galactic and extra-galactic sources. The missions planned for the near future will be briefly summarized
The emission spectrum of the strong Fe II emitter BAL Seyfert 1 galaxy IRAS 07598+6508
The narrow-line Seyfert 1 galaxy IRAS 07598+6508 is known to be a stong Fe II
emitter. The analysis of several high S/N ratio spectra shows that its spectrum
is dominated by a relatively narrow "broad line" region (1 780 km s
FWHM) emitting not only Fe II, but also Ti II and Cr II lines. Although we were
unable to find a completely satisfactory physical model, we got the best
agreement with the observations with collisional rather than radiative models,
with a high density (n=10 cm), a high column density
(N=10 cm) and a microturbulence of 100 km s. This
BLR is qualitatively similar to the one observed in I Zw 1. We have not found
traces in IRAS 07598+6508 of the narrow line regions found in I Zw 1.Comment: 15 pages, 4 figures, accepted by A&
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 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
Determining the sign of at long baseline neutrino experiments
Recently it is advocated that high intensity and low energy neutrino beams should be built to probe the mixing angle to
a level of a few parts in . Experiments using such beams will have better
signal to background ratio in searches for oscillations. We
propose that such experiments can also determine the sign of even
if the beam consists of {\it neutrinos} only. By measuring the transitions in two different energy ranges, the effects due to
propagation of neutrinos through earth's crust can be isolated and the sign of
can be determined. If the sensitivity of an experiment to
is , then the same experiment is automatically sensitive to matter
effects and the sign of for values of .Comment: Title changed and paper rewritten. 4 pages, 1 figure, revte
Manifestations of Extra Dimensions in a Neutrino Telescope
Theories with large extra dimensions provide the possibility that a flavor
neutrino, localized in a 3+1 brane, can mix with a singlet neutrino living in
the bulk. This mixing leads to unconventional patterns of neutrino matter
oscillations and we examine in details how these oscillations depend upon two
parameters: the brane-bulk coupling and the effective mass of the
flavor neutrino inside matter. We find that high energy GeV)
neutrinos, to be detected by neutrino telescopes, can give signals of
extra dimensions. With a 1 k neutrino telescope extra dimensions with
radius down to can be tested directly, while for smaller radius an
indirect evidence can be established.Comment: 14 pages, 5 figures, added conclusion
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
Indagini briologiche in aree urbane: diversitĂ briofitica dei centri abitati di Erice (Trapani) e Belmonte Mezzagno (Palermo).
Bryologic surveys in urban areas: bryophyte diversity of the population centers of Erice (province of Trapani)
and Belmonte Mezzagno ((province of Palermo). The bryophytic flora of the towns of Erice (Trapani) and Belmonte Mezzagno
(Palermo) have been studied. The first consists of 53 taxa (42 mosses and 11 liverwort), two of which are new for
the province of Trapani, the second of 40 taxa (38 mosses and 2 liverworts), one of which new for the province of Palermo.
A comparison between the studied bryofloras and those of other Sicilian urban areas shows that Ericeâs bryophytic flora is,
given its size, rich in species and families
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