8,371 research outputs found
Geo-neutrinos
We review a new interdisciplinary field between Geology and Physics: the
study of the Earth's geo-neutrino flux. We describe competing models for the
composition of the Earth, present geological insights into the make up of the
continental and oceanic crust, those parts of the Earth that concentrate Th and
U, the heat producing elements, and provide details of the regional settings in
the continents and oceans where operating and planned detectors are sited.
Details are presented for the only two operating detectors that are capable of
measuring the Earth's geo-neutrinos flux: Borexino and KamLAND; results
achieved to date are presented, along with their impacts on geophysical and
geochemical models of the Earth. Finally, future planned experiments are
highlighted
GATE : a simulation toolkit for PET and SPECT
Monte Carlo simulation is an essential tool in emission tomography that can
assist in the design of new medical imaging devices, the optimization of
acquisition protocols, and the development or assessment of image
reconstruction algorithms and correction techniques. GATE, the Geant4
Application for Tomographic Emission, encapsulates the Geant4 libraries to
achieve a modular, versatile, scripted simulation toolkit adapted to the field
of nuclear medicine. In particular, GATE allows the description of
time-dependent phenomena such as source or detector movement, and source decay
kinetics. This feature makes it possible to simulate time curves under
realistic acquisition conditions and to test dynamic reconstruction algorithms.
A public release of GATE licensed under the GNU Lesser General Public License
can be downloaded at the address http://www-lphe.epfl.ch/GATE/
Status of Evidence for Neutrinoless Double Beta Decay, and the Future: GENIUS and GENIUS-TF
The first evidence for neutrinoless double beta decay has been observed in
the HEIDELBERG-MOSCOW experiment, which is the most sensitive double beta decay
experiment since ten years. This is the first evidence for lepton number
violation and proves that the neutrino is a Majorana particle. It further shows
that neutrino masses are degenerate. In addition it puts several stringent
constraints on other physics beyond the Standard Model. The result from the
HEIDELBERG-MOSCOW experiment is consistent with recent results from CMB
investigations, with high energy cosmic rays, with the result from the g-2
experiment and with recent theoretical work. It is indirectly supported by the
analysis of other Ge double beta experiments.
The new project GENIUS will cover a wide range of the parameter space of
predictions of SUSY for neutralinos as cold dark matter. Further it has the
potential to be a real-time detector for low-energy ( and Be) solar
neutrinos.
A GENIUS Test Facility has come into operation on May 5, 2003. This is the
first time that this novel technique for extreme background reduction in search
for rare decays is applied under the background conditions of an underground
laboratory.Comment: 20 pages, 13 figure
GEANT4 : a simulation toolkit
Abstract Geant4 is a toolkit for simulating the passage of particles through matter. It includes a complete range of functionality including tracking, geometry, physics models and hits. The physics processes offered cover a comprehensive range, including electromagnetic, hadronic and optical processes, a large set of long-lived particles, materials and elements, over a wide energy range starting, in some cases, from 250 eV and extending in others to the TeV energy range. It has been designed and constructed to expose the physics models utilised, to handle complex geometries, and to enable its easy adaptation for optimal use in different sets of applications. The toolkit is the result of a worldwide collaboration of physicists and software engineers. It has been created exploiting software engineering and object-oriented technology and implemented in the C++ programming language. It has been used in applications in particle physics, nuclear physics, accelerator design, space engineering and medical physics. PACS: 07.05.Tp; 13; 2
The Future of Neutrino Mass Measurements: Terrestrial, Astrophysical, and Cosmological Measurements in the Next Decade. Highlights of the NuMass 2013 Workshop. Milano, Italy, February 4 - 7, 2013
The third Workshop of the NuMass series ("The Future of Neutrino Mass
Measurements: Terrestrial, Astrophysical, and Cosmological Measurements in the
Next Decade: NuMass 2013") was held at Dipartimento di Fisica "G. Occhialini,
University of Milano-Bicocca in Milano, Italy, on 4-7 February 2013. The goal
of this international workshop was to review the status and future of direct
and indirect neutrino mass measurements in the laboratory as well as from
astrophysical and cosmological observations. This paper collects most of the
contributions presented during the Workshop
Actinide-rich and Actinide-poor -Process Enhanced Metal-Poor Stars do not Require Separate -Process Progenitors
The astrophysical production site of the heaviest elements in the universe
remains a mystery. Incorporating heavy element signatures of metal-poor,
-process enhanced stars into theoretical studies of -process production
can offer crucial constraints on the origin of heavy elements. In this study,
we introduce and apply the "Actinide-Dilution with Matching" model to a variety
of stellar groups ranging from actinide-deficient to actinide-enhanced to
empirically characterize -process ejecta mass as a function of electron
fraction. We find that actinide-boost stars do not indicate the need for a
unique and separate -process progenitor. Rather, small variations of neutron
richness within the same type of -process event can account for all observed
levels of actinide enhancements. The very low-, fission-cycling ejecta of
an -process event need only constitute 10-30% of the total ejecta mass to
accommodate most actinide abundances of metal-poor stars. We find that our
empirical distributions of ejecta are similar to those inferred from
studies of GW170817 mass ejecta ratios, which is consistent with neutron-star
mergers being a source of the heavy elements in metal-poor, -process
enhanced stars.Comment: 14 pages, 11 figures, Submitted to Ap
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