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

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

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

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 $\sim$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

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

The application of FLUKA to dosimetry and radiation therapy

ISSN:0144-8420ISSN:1742-340