2,910 research outputs found
City of Cleburne, Texas v. Cleburne Living Center, Inc.: The Mentally Retarded and the Deimse of Intermediate Scrutiny
Mono-everything: combined limits on dark matter production at colliders from multiple final states
Searches for dark matter production at particle colliders are complementary
to direct-detection and indirect-detection experiments, and especially powerful
for small masses, GeV. An important collider dark matter signature
is due to the production of a pair of these invisible particles with the
initial-state radiation of a standard model particle. Currently, collider
searches use individual and nearly orthogonal final states to search for
initial-state jets, photons or massive gauge bosons. We combine these results
across final states and across experiments to give the strongest current
collider-based limits in the context of effective field theories, and map these
to limits on dark matter interactions with nuclei and to dark matter
self-annhiliation
Sensitivity of future collider facilities to WIMP pair production via effective operators and light mediators
We present extrapolations of the current mono-jet searches at the LHC to
potential future hadron collider facilities: LHC14, as well as colliders
with or 100 TeV. We consider both the effective operator approach
as well as one example of a light mediating particle
Tort Reform : Minnesota Does Not Need Legislation That Makes Victims Pay for the Negligence of Others
Tort Reform : Minnesota Does Not Need Legislation That Makes Victims Pay for the Negligence of Others
A detailed study of the gamma-ray supernova remnant RX J1713.7-3946 with H.E.S.S.
The H.E.S.S. telescope system -- an array of four imaging atmospheric Cherenkov telescopes situated in Namibia -- aims at exploring non-thermal processes in the universe by means of very-high-energy (VHE) gamma rays. Its large field of view combined with unprecedented sensitivity enables detailed spectral and morphological studies of extended VHE gamma-ray sources. The shell-type supernova remnant RX J1713.7-3946 is such a source. It is located in the Galactic plane, constellation scorpius, and has a diameter of 1 degree. H.E.S.S. observations of this source were conducted in 2003, 2004, and 2005. A thorough discussion of the methodology of the analysis of (extended) VHE gamma-ray sources is given. The systematic uncertainties involved in different stages of the analysis are explored. Detailed morphological and spectral studies reveal the VHE aspects of RX J1713.7-3946. Gamma rays are detected throughout the whole remnant. The emission resembles a shell structure strikingly similar to the X-ray image. The differential gamma-ray spectrum is measured over a large energy range, no spatial variation is found. The data recorded in three different years are in good agreement. The origin of the gamma-ray emission is discussed for a leptonic and a hadronic scenario. The latter case is favoured, but no decisive conclusion can be drawn
Introducing the MeVCube concept: a CubeSat for MeV observations
Despite the impressive progress achieved both by X-ray and gamma-ray
observatories in the last few decades, the energy range between
and remains poorly explored.
COMPTEL, on-board the Compton Gamma-Ray Observatory (CGRO, -),
opened the MeV gamma-ray band as a new window to astronomy, performing the
first all-sky survey in the energy range from to .
More than years after the de-orbit of CGRO, no successor mission is yet
operating. Over the past years many concepts have been proposed, for new
observatories exploring different configurations and imaging techniques; a
selection of the most recent ones includes AMEGO, ETCC, GECCO and COSI. We
propose here a novel concept for a Compton telescope based on the CubeSat
standard, named MeVCube, with the advantages of small cost and relatively short
development time. The scientific payload is based on two layers of pixelated
Cadmium-Zinc-Telluride (CdZnTe) detectors, coupled with low-power read-out
electronics (ASIC, VATA450.3). The performance of the read-out electronics and
CdZnTe custom designed detectors have been measured extensively at DESY. The
performance of the telescope is accessed through simulations: despite a small
effective area limited to a few , MeVCube can reach an angular
resolution of and a sensitivity comparable to the one achieved by
the last generation of large-scale satellites like COMPTEL and INTEGRAL.
Combined with a large field-of-view and a moderate cost, MeVCube can be a
powerful instrument for transient observations and searches of electromagnetic
counterparts of gravitational wave events
Introducing the MeVCube concept: a CubeSat for MeV observations
Despite the impressive progress achieved both by X-ray and gamma-ray observatories in the last few decades, the energy range between ⌠200 keV and ⌠50 MeV remains poorly explored. COMPTEL, on-board the Compton Gamma-Ray Observatory (CGRO, 1991-2000), opened the MeV gamma-ray band as a new window to astronomy, performing the first all-sky survey in the energy range from 0.75 to 30 MeV. More than 20 years after the de-orbit of CGRO, no successor mission is yet operating. Over the past years many concepts have been proposed, for new observatories exploring different configurations and imaging techniques; a selection of the most recent ones includes AMEGO, ETCC, GECCO and COSI.
We propose here a novel concept for a Compton telescope based on the CubeSat standard, named MeVCube, with the advantages of small cost and relatively short development time. The scientific payload is based on two layers of pixelated Cadmium-Zinc-Telluride (CdZnTe) detectors, coupled with low-power read-out electronics (ASIC, VATA450.3). The performance of the read-out electronics and CdZnTe custom designed detectors have been measured extensively at DESY [1]. The performance of the telescope is accessed through simulations: despite a small effective area limited to a few cm2, MeVCube can reach an angular resolution of 1.5° and a sensitivity comparable to the one achieved by the last generation of large-scale satellites like COMPTEL and INTEGRAL. Combined with a large field-of-view and a moderate cost, MeVCube can be a powerful instrument for transient observations and searches of electromagnetic counterparts of gravitational wave events.Peer Reviewe
Evaluation of a permeability-porosity relationship in a low permeability creeping material using a single transient test
A method is presented for the evaluation of the permeability-porosity
relationship in a low-permeability porous material using the results of a
single transient test. This method accounts for both elastic and non-elastic
deformations of the sample during the test and is applied to a hardened class G
oil well cement paste. An initial hydrostatic undrained loading is applied to
the sample. The generated excess pore pressure is then released at one end of
the sample while monitoring the pore pressure at the other end and the radial
strain in the middle of the sample during the dissipation of the pore pressure.
These measurements are back analysed to evaluate the permeability and its
evolution with porosity change. The effect of creep of the sample during the
test on the measured pore pressure and volume change is taken into account in
the analysis. This approach permits to calibrate a power law
permeability-porosity relationship for the tested hardened cement paste. The
porosity sensitivity exponent of the power-law is evaluated equal to 11 and is
shown to be mostly independent of the stress level and of the creep strains
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