41 research outputs found
Phenomenological Consequences of Soft Leptogenesis
Soft supersymmetry breaking terms involving heavy singlet sneutrinos can be
the dominant source of leptogenesis. The relevant range of parameters is
different from standard leptogenesis: a lighter Majorana mass, M < 10^9 GeV
(allowing a solution of the gravitino problem), and smaller Yukawa couplings,
Y_N < 10^{-4}. We investigate whether the various couplings of the singlet
sneutrinos, which are constrained by the requirement of successful `soft
leptogenesis', can have observable phenomenological consequences. Specifically,
we calculate the contributions of the relevant soft supersymmetric breaking
terms to the electric dipole moments of the charged leptons and to lepton
flavor violating decays. Our result is that these contributions are small.Comment: 11 pages, 1 figure; v2: an additional contribution is considered
(modifying: fig. 1, eq. 10-13, 22) and a reference added. Conclusions
unchange
A Machine Vision System for Evaluation of Planter Seed Spatial Distribution
Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a Technical Paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 4 (2002): V. Alchanatis, Y. Kashti, and R. Brikman. A Machine Vision System for Evaluation of Planter Seed Spatial Distribution
Observing Ultra High Energy Cosmic Particles from Space: SEUSO, the Super Extreme Universe Space Observatory Mission
The experimental search for ultra high energy cosmic messengers, from eV to beyond eV, at the very end of the known energy
spectrum, constitutes an extraordinary opportunity to explore a largely unknown
aspect of our universe. Key scientific goals are the identification of the
sources of ultra high energy particles, the measurement of their spectra and
the study of galactic and local intergalactic magnetic fields. Ultra high
energy particles might, also, carry evidence of unknown physics or of exotic
particles relics of the early universe. To meet this challenge a significant
increase in the integrated exposure is required. This implies a new class of
experiments with larger acceptances and good understanding of the systematic
uncertainties. Space based observatories can reach the instantaneous aperture
and the integrated exposure necessary to systematically explore the ultra high
energy universe. In this paper, after briefly summarising the science case of
the mission, we describe the scientific goals and requirements of the SEUSO
concept. We then introduce the SEUSO observational approach and describe the
main instrument and mission features. We conclude discussing the expected
performance of the mission
Propagation of ultrahigh energy nuclei in clusters of galaxies: resulting composition and secondary emissions
We study the survival of ultrahigh energy nuclei injected in clusters of
galaxies, as well as their secondary neutrino and photon emissions, using a
complete numerical propagation method and a realistic modeling of the magnetic,
baryonic and photonic backgrounds. It is found that the survival of heavy
nuclei highly depends on the injection position and on the profile of the
magnetic field. Taking into account the limited lifetime of the central source
could also lead in some cases to the detection of a cosmic ray afterglow,
temporally decorrelated from neutrino and gamma ray emissions.
We calculate that the diffusive neutrino flux around 1 PeV coming from
clusters of galaxies may have a chance to be detected by current instruments.
The observation of single sources in neutrinos and in gamma rays produced by
ultrahigh energy cosmic rays will be more difficult. Signals coming from lower
energy cosmic rays (E < 1 PeV), if they exist, might however be detected by
Fermi, for reasonable sets of parameters.Comment: 19 pages, 15 figures, version to appear in ApJ (minor changes
Search for Anisotropy of Ultra-High Energy Cosmic Rays with the Telescope Array Experiment
We study the anisotropy of Ultra-High Energy Cosmic Ray (UHECR) events
collected by the Telescope Array (TA) detector in the first 40 months of
operation. Following earlier studies, we examine event sets with energy
thresholds of 10 EeV, 40 EeV, and 57 EeV. We find that the distributions of the
events in right ascension and declination are compatible with an isotropic
distribution in all three sets. We then compare with previously reported
clustering of the UHECR events at small angular scales. No significant
clustering is found in the TA data. We then check the events with E>57 EeV for
correlations with nearby active galactic nuclei. No significant correlation is
found. Finally, we examine all three sets for correlations with the large-scale
structure of the Universe. We find that the two higher-energy sets are
compatible with both an isotropic distribution and the hypothesis that UHECR
sources follow the matter distribution of the Universe (the LSS hypothesis),
while the event set with E>10 EeV is compatible with isotropy and is not
compatible with the LSS hypothesis at 95% CL unless large deflection angles are
also assumed. We show that accounting for UHECR deflections in a realistic
model of the Galactic magnetic field can make this set compatible with the LSS
hypothesis.Comment: 10 pages, 9 figure
Searching for a Correlation Between Cosmic-Ray Sources Above 10^{19} eV and Large-Scale Structure
We study the anisotropy signature which is expected if the sources of ultra
high energy, >10^{19} eV, cosmic-rays (UHECRs) are extragalactic and trace the
large scale distribution of luminous matter. Using the PSCz galaxy catalog as a
tracer of the large scale structure (LSS), we derive the expected all sky
angular distribution of the UHECR intensity. We define a statistic, that
measures the correlation between the predicted and observed UHECR arrival
direction distributions, and show that it is more sensitive to the expected
anisotropy signature than the power spectrum and the two point correlation
function. The distribution of the correlation statistic is not sensitive to the
unknown redshift evolution of UHECR source density and to the unknown strength
and structure of inter-galactic magnetic fields. We show, using this statistic,
that recently published >5.7x10^{19} eV Auger data are inconsistent with
isotropy at ~98% CL, and consistent with a source distribution that traces LSS,
with some preference to a source distribution that is biased with respect to
the galaxy distribution. The anisotropy signature should be detectable also at
lower energy, >4x10^{19} eV. A few fold increase of the Auger exposure is
likely to increase the significance to >99% CL, but not to >99.9% CL (unless
the UHECR source density is comparable or larger than that of galaxies). In
order to distinguish between different bias models, the systematic uncertainty
in the absolute energy calibration of the experiments should be reduced to well
below the current ~25%.Comment: 17 pages, 8 figures. v2: reference added, typos corrected, accepted
to JCA
SUSY Renormalization Group Effects in Ultra High Energy Neutrinos
We have explored the question of whether the renormalization group running of
the neutrino mixing parameters in the Minimal Supersymmetric Standard Model is
detectable with ultra-high energy neutrinos from active galactic nuclei (AGN).
We use as observables the ratios of neutrino fluxes produced at the AGN,
focusing on four different neutrino production models:
= (1:2:0), (0:1:0), (1:0:0), and (1:1:0).
The prospects for observing deviations experimentally are taken into
consideration, and we find out that it is necessary to impose a cut-off on the
transferred momentum of GeV. However, this condition,
together with the expected low value of the diffuse AGN neutrino flux, yields a
negligible event rate at a km-scale Cherenkov detector such as IceCube.Comment: 26 pages, 9 figures. Version accepted for publication in JHE
The Estimation of Urban Domestic Water Use: A Study with Reference to Leeds
The privatisation of the water industry in 1989 highlighted the need for greater precision in planning water resources. The absence of any large scale research on the pattern of domestic water use (DWU) accentuated the ignorance of the utilisation of more than 50% of supplies.
With the gradual introduction of domestic metering during the mid 1980s, there has been a considerable growth in information in this area. Since privatisation, the number of metered properties has risen and now amounts to 6% of the population. The data accumulated on the subject of domestic water use have increased the ability to understand better some of the processes involved, although there remained two major stumbling blocks on the way to analysing fully these data.
Firstly, the nature of the meters and the frequency with which they are read makes the understanding of the components which make up domestic water use almost impossible; and secondly, the profile of metered households is, by its nature, biased towards new properties which often have meters installed in them automatically, and small households, who opt to have a meter installed as they perceive financial gain resulting from it.
Under such circumstances the data containing the results of two surveys conducted by Yorkshire Water in 1992 are used in a new approach to geographical modelling. In the first stage the components with the highest DWU coefficients are determined by statistical means. A microsimulation technique, which lies beyond the scope of this work, is used in the second stage to model the spatial distribution of domestic water use in Leeds by using household components derived from the data by statistical means. The uniqueness of this thesis is in its association of these two techniques.
The overall conceptual analysis of all the issues involved in DWU, together with results of the two analyses, allow a better understanding of domestic water use of all properties, whether they possess a meter or not, from the smallest geographical unit - the household - to any spatial aggregation required.
The implications of this model for policy formulation and management strategy are numerous. The ability to forecast demand whilst incorporating environmental and economic scenarios, combined with the ability to concentrate on any geographical scale, renders this approach extremely useful in future developments which the water industry is about to enter
Outdoor testing of agricultural cladding materials
In this research, optical and mechanical properties of three different types of (polyethylene) PE plastic films commonly used for cladding greenhouse in TURKEY were studied. The three types of plastic films were UV (Ultraviolet), UV-IR (Ultraviolet and Infrared) and UV-IR-AF (Ultraviolet, Infrared and Antifog). For this study, three different experimental greenhouses developed and constructed by Institute of Agricultural Engineering ARO, the Volcani Center were used. One of the experimental greenhouses was used to investigate the effect of agro-chemical (sulfur) on the mechanical properties of cladding materials. This greenhouse had 30 identical sections. Each film was fixed on a rectangular aluminium frame. The frames were mounted on these sections. The second greenhouse was used to investigate the solar radiation transmission characteristic of plastic films. The last one was used to investigate the ageing of cladding materials in general. The experiments on the effect of sulfur evaporation on plastic films were started in June 1997 for period of 3 months. The results with sulfur evaporation on mechanical properties of PE films indicated that the elongation that take place in PE films treated with sulfur reduced about 60-80 %
Very-high-energy astrophysical neutrinos with IceCube
IceCube is a ≳TeV neutrino observatory operating at the South Pole. Ice-Cube has observed a flux of neutrinos of astrophysical origin, with energies beyond 2 PeV. However the sources of these neutrinos have not yet been identified. A summary of various IceCube observations is presented. The results discussed were obtained through several different analysis methods, which have varying sensitivity to the different neutrino flavors. A discussion of the spectral fit obtained for the various event selections is included, as well as the constraints on the astrophysical neutrino flavor flux ratio. Several attempts by IceCube to identify the sources of these neutrinos are described. These include studies correlating neutrino events with catalogs of sources as well as selfcorrelations among IceCube’s neutrinos. The observations of astrophysical neutrinos are limited by statistics. So an upgrade of IceCube, including a larger detector and a surface veto is planned. This upgrade is briefly discussed