39 research outputs found
Introduction
Trois thèmes de littérature italienne médiévale : voilà une tâche trop facile et trop difficile à la fois. Quoi de plus simple que de penser à Dante, Pétrarque, Boccace ? Et quoi de plus compliqué que de trouver des auteurs et des articles qui ne répètent pas à nouveau sur les « Tre Corone » – le plus souvent avec un maquillage dicté par la dernière mode – les analyses et les interprétations qui pendant deux siècles ont rempli des salles entières de bibliothèques ? Ou qui n’inventent pas des ..
Detector for imaging of explosions: present status and future prospects with higher energy X-rays
The detector for imaging of explosions (DIMEX) is in operation at the
synchrotron radiation (SR) beam-line at VEPP-3 electron ring at Budker INP
since 2002. DIMEX is based on one-coordinate gas ionization chamber filled with
Xe-CO2(3:1) mixture at 7atm, and active Frisch-grid made of Gas Electron
Multiplier (GEM). The detector has spatial resolution of ~0.2mm and dynamic
range of ~100 that allows to realize the precision of signal measurement at a
percent level. The frame rate can be tuned up to 8 MHz (125 ns per image) and
up to 32 images can be stored in one shot. At present DIMEX is used with the
X-ray beam from 2T wiggler that has ~20 keV average energy. Future possibility
to install similar detector at the SR beam-line at VEPP-4 electron ring is
discussed.Comment: 14 pages, 15 figures. Submitted to JINS
Introduction
Trois thèmes de littérature italienne médiévale : voilà une tâche trop facile et trop difficile à la fois. Quoi de plus simple que de penser à Dante, Pétrarque, Boccace ? Et quoi de plus compliqué que de trouver des auteurs et des articles qui ne répètent pas à nouveau sur les « Tre Corone » – le plus souvent avec un maquillage dicté par la dernière mode – les analyses et les interprétations qui pendant deux siècles ont rempli des salles entières de bibliothèques ? Ou qui n’inventent pas des ..
Simulations of neutron background in a time projection chamber relevant to dark matter searches
Presented here are results of simulations of neutron background performed for
a time projection chamber acting as a particle dark matter detector in an
underground laboratory. The investigated background includes neutrons from rock
and detector components, generated via spontaneous fission and (alpha, n)
reactions, as well as those due to cosmic-ray muons. Neutrons were propagated
to the sensitive volume of the detector and the nuclear recoil spectra were
calculated. Methods of neutron background suppression were also examined and
limitations to the sensitivity of a gaseous dark matter detector are discussed.
Results indicate that neutrons should not limit sensitivity to WIMP-nucleon
interactions down to a level of (1 - 3) x 10^{-8} pb in a 10 kg detector.Comment: 27 pages (total, including 3 tables and 11 figures). Accepted for
publication in Nuclear Instruments and Methods in Physics Research - Section
Upper limit on the ultra-high-energy photon flux from AGASA and Yakutsk data
We present the interpretation of the muon and scintillation signals of
ultra-high-energy air showers observed by AGASA and Yakutsk extensive air
shower array experiments. We consider case-by-case ten highest energy events
with known muon content and conclude that at the 95% confidence level (C.L.)
none of them was induced by a primary photon. Taking into account statistical
fluctuations and differences in the energy estimation of proton and photon
primaries, we derive an upper limit of 36% at 95% C.L. on the fraction of
primary photons in the cosmic-ray flux above 10^20 eV. This result disfavors
the Z-burst and superheavy dark-matter solutions to the GZK-cutoff problem.Comment: revtex, 8 pages, 4 figure
Muon-Induced Background Study for Underground Laboratories
We provide a comprehensive study of the cosmic-ray muon flux and induced
activity as a function of overburden along with a convenient parameterization
of the salient fluxes and differential distributions for a suite of underground
laboratories ranging in depth from 1 to 8 km.w.e.. Particular attention
is given to the muon-induced fast neutron activity for the underground sites
and we develop a Depth-Sensitivity-Relation to characterize the effect of such
background in experiments searching for WIMP dark matter and neutrinoless
double beta decay.Comment: 18 pages, 28 figure
The application of FLUKA to dosimetry and radiation therapy
The FLUKA Monte Carlo code has been evolving over the last several decades and is now widely used for radiation shielding calculations. In order to facilitate the use of FLUKA in dosimetry and therapy applications, supporting software has been developed to allow the direct conversion of the output files from standard CT-scans directly into a voxel geometry for transport within FLUKA. Since the CT-scan information essentially contains only the electron density information over the scanned volume, one needs the specific compositions for each voxel individually. We present here the results of a simple algorithm to assign tissues in the human body to one of four categories: soft-tissue, hard-bone, trabecular-bone and porous-lung. In addition, we explore the problem of the pathlength distributions in porous media such as trabecular bone. A mechanism will be implemented within FLUKA to allow for variable multipal fixed density materials to accommodate the pathlength distributions discovere
R&D on co-working transport schemes in Geant4
A research and development (R&D) project related to the extension of the
Geant4 toolkit has been recently launched to address fundamental methods in
radiation transport simulation. The project focuses on simulation at different
scales in the same experimental environment; this problem requires new methods
across the current boundaries of condensed-random-walk and discrete transport
schemes. The new developments have been motivated by experimental requirements
in various domains, including nanodosimetry, astronomy and detector
developments for high energy physics applications.Comment: To be published in the Proceedings of the CHEP (Computing in High
Energy Physics) 2009 conferenc
Towards event-by-event studies of the ultrahigh-energy cosmic-ray composition
We suggest a method which improves the precision of studies of the primary
composition of ultra-high-energy cosmic rays. Two principal ingredients of the
method are (1) comparison of the observed and simulated parameters for
individual showers, without averaging over arrival directions and (2)
event-by-event selection of simulated showers by the physical observables and
not by the reconstructed primary parameters. A detailed description of the
algorithm is presented and illustrated by several examples.Comment: 27 pages, 6 figures; v2: 30 pages, journal versio
Yvan G. Lepage, éd. — Les rédactions en vers du « Couronnement de Louis », 1978 (" Textes litt. franç. ", 261)
Fassó Andréa. Yvan G. Lepage, éd. — Les rédactions en vers du « Couronnement de Louis », 1978 (" Textes litt. franç. ", 261). In: Cahiers de civilisation médiévale, 25e année (n°97), Janvier-mars 1982. pp. 67-69