UNT Libraries Government Documents Department - 117,647 Matching Results

Search Results

prev Results: 74991 - 75014 next
open access

Monte Carlo Simulations of High-speed, Time-gated MCP-based X-ray Detectors: Saturation Effects in DC and Pulsed Modes and Detector Dynamic Range

Description: We present here results of continued efforts to understand the performance of microchannel plate (MCP)–based, high-speed, gated, x-ray detectors. This work involves the continued improvement of a Monte Carlo simulation code to describe MCP performance coupled with experimental efforts to better characterize such detectors. Our goal is a quantitative description of MCP saturation behavior in both static and pulsed modes. We have developed a new model of charge buildup on the walls of the MCP cha… more
Date: October 31, 2008
Creator: Craig Kruschwitz, Ming Wu, Ken Moy, Greg Rochau
Item Type: Refine your search to only Article
open access

Monte Carlo Simulations of High-Speed, Time-Gated MCP-based X-ray Detectors: Saturation Effects in DC Pulsed Modes and Detector Dynamic Range

Description: We present here results of continued efforts to understand the performance of microchannel plate (MCP)–based, high-speed, gated, x-ray detectors. This work involves the continued improvement of a Monte Carlo simulation code to describe MCP performance coupled with experimental efforts to better characterize such detectors. Our goal is a quantitative description of MCP saturation behavior in both static and pulsed modes. A new model of charge buildup on the walls of the MCP channels is briefly d… more
Date: May 30, 2008
Creator: Craig Kruschwitz, Ming Wu, Ken Moy, Greg Rochau
Item Type: Refine your search to only Article
open access

Monte Carlo simulations of microchannel plate detectors I: steady-state voltage bias results

Description: X-ray detectors based on straight-channel microchannel plates (MCPs) are a powerful diagnostic tool for two-dimensional, time-resolved imaging and timeresolved x-ray spectroscopy in the fields of laser-driven inertial confinement fusion and fast z-pinch experiments. Understanding the behavior of microchannel plates as used in such detectors is critical to understanding the data obtained. The subject of this paper is a Monte Carlo computer code we have developed to simulate the electron cascade … more
Date: July 1, 2008
Creator: Ming Wu, Craig Kruschwitz, Dane Morgan, Jiaming Morgan
Item Type: Refine your search to only Article
open access

Monte Carlo simulations of phosphate polyhedron connectivity in glasses

Description: Monte Carlo simulations of phosphate tetrahedron connectivity distributions in alkali and alkaline earth phosphate glasses are reported. By utilizing a discrete bond model, the distribution of next-nearest neighbor connectivities between phosphate polyhedron for random, alternating and clustering bonding scenarios was evaluated as a function of the relative bond energy difference. The simulated distributions are compared to experimentally observed connectivities reported for solid-state two-dim… more
Date: January 1, 2000
Creator: ALAM,TODD M.
Item Type: Refine your search to only Report
open access

Monte Carlo Simulations of Segregation in Pt-Ni Catalyst Nanoparticles

Description: We have investigated the segregation of Pt atoms in the surfaces of Pt-Ni nanoparticles, using Modified Embedded Atom Model potentials and the Monte Carlo method. The nanoparticles are assumed to have disordered fcc configurations at two fixed overall concentrations (50 at. percent Pt and 75 at. percent Pt). We use four kinds of nanoparticle shapes [cube, tetrahedron, octahedron, and cubo-octahedron] terminated by {l_brace}111{r_brace} and {l_brace}100{r_brace} facets to examine the extent of t… more
Date: April 1, 2004
Creator: Wang, Guofeng; Van Hove, Michel A.; Ross, Philip N. & Baskes, M.I.
Item Type: Refine your search to only Article
open access

Monte carlo simulations of segregation in Pt-Re catalyst nanoparticles

Description: We have investigated the segregation of Pt atoms to the surfaces of Pt-Re nanoparticles using the Monte Carlo method and Modified Embedded Atom Method potentials that we have developed for Pt-Re alloys. The Pt75Re25 nanoparticles (containing from 586 to 4033 atoms) are assumed to have disordered fcc configurations and cubo-octahedral shapes (terminated by {l_brace}111{r_brace} and {l_brace}100{r_brace} facets), while the Pt50Re50 and Pt25Re75 nanoparticles (containing from 587 to 4061 atoms) ar… more
Date: April 1, 2004
Creator: Wang, Guofeng; Van Hove, M.A.; Ross, P.N. & Baskes, M.I.
Item Type: Refine your search to only Article
open access

Monte Carlo Simulator to Study High Mass X-Ray Binary System

Description: We have developed a Monte Carlo simulator for astrophysical objects, which incorporate the transportation of X-ray photons in photoionized plasma. We applied the code to X-ray spectra of high mass X-ray binaries, Vela X-1 and GX 301-2, obtained with Chandra HETGS. By utilizing the simulator, we have successfully reproduced many emission lines observed from Vela X-1. The ionization structure and the matter distribution in the Vela X-1 system are deduced. For GX 301-2, we have derived the physica… more
Date: July 8, 2005
Creator: Watanabe, Shin; Nagase, Fumiaki; Takahashi, Tadayuki; /Sagamihara, Inst. Space Astron. Sci.; Sako, Masao; Kahn, Steve M. et al.
Item Type: Refine your search to only Article
open access

Monte Carlo source convergence and the Whitesides problem

Description: The issue of fission source convergence in Monte Carlo eigenvalue calculations is of interest because of the potential consequences of erroneous criticality safety calculations. In this work, the authors compare two different techniques to improve the source convergence behavior of standard Monte Carlo calculations applied to challenging source convergence problems. The first method, super-history powering, attempts to avoid discarding important fission sites between generations by delaying sto… more
Date: February 25, 2000
Creator: Blomquist, R. N.
Item Type: Refine your search to only Article
open access

Monte Carlo Study of the Measurement of the top - anti-top Production Cross-Section in the Muon + Jets Channel with the D0-Detector at s**(1/2) = 1.96-TeV

Description: A measurement of the t{bar t} production cross section at {radical}s = 1.96 TeV with the D0 detector using simulated events is performed. The final state containing a muon and jets is examined including all methods of measuring signal efficiencies and the estimation of the background contributions. Especially, the identification efficiency and properties of muons are studied.
Date: March 1, 2004
Creator: Meyer, Jorg Manfred
Item Type: Refine your search to only Report
open access

A Monte Carlo Study of the Momentum Dependence on the Results of Tracking Unknown Particle Species in the BaBar Detector

Description: Abstract: The BABAR experiment is composed of an international collaboration that will test the Standard Model prediction of CP violation. To accomplish this a new detector was constructed at the asymmetric B Factory, located at the Stanford Linear Accelerator Center. The tests will shed some light on the origins of CP violation, which is an important aspect in explaining the matter/antimatter asymmetry in the universe. In particular, the BABAR experiment will measure CP violation in the neutra… more
Date: April 6, 2007
Creator: Sewerynek, Stephen
Item Type: Refine your search to only Report
open access

Monte carlo Techniques for the Comprehensive Modeling of Isotopic Inventories in Future Nuclear Systems and Fuel Cycles

Description: The development of Monte Carlo techniques for isotopic inventory analysis has been explored in order to facilitate the modeling of systems with flowing streams of material through varying neutron irradiation environments. This represents a novel application of Monte Carlo methods to a field that has traditionally relied on deterministic solutions to systems of first-order differential equations. The Monte Carlo techniques were based largely on the known modeling techniques of Monte Carlo radiat… more
Date: July 30, 2005
Creator: Wilson, Paul P.H.
Item Type: Refine your search to only Report
open access

Monte Carlo Treatment Planning for Molecular Targeted Radiotherapy within the MINERVA System

Description: The aim of this project is to extend accurate and patient-specific treatment planning to new treatment modalities, such as molecular targeted radiation therapy, incorporating previously crafted and proven Monte Carlo and deterministic computation methods. A flexible software environment is being created that allows planning radiation treatment for these new modalities and combining different forms of radiation treatment with consideration of biological effects. The system uses common input inte… more
Date: September 22, 2004
Creator: Lehmann, J; Siantar, C H; Wessol, D E; Wemple, C A; Nigg, D; Cogliati, J et al.
Item Type: Refine your search to only Article
open access

Monte Carlo without chains

Description: A sampling method for spin systems is presented. The spin lattice is written as the union of a nested sequence of sublattices, all but the last with conditionally independent spins, which are sampled in succession using their marginals. The marginals are computed concurrently by a fast algorithm; errors in the evaluation of the marginals are offset by weights. There are no Markov chains and each sample is independent of the previous ones; the cost of a sample is proportional to the number of sp… more
Date: December 12, 2007
Creator: Chorin, Alexandre J.
Item Type: Refine your search to only Article
open access

Monte Carol-Based Dosimetry of Beta-Emitters for Intravascular Brachytherapy

Description: Monte Carlo simulations for radiation dosimetry and the experimental verifications of the simulations have been developed for the treatment geometry of intravascular brachytherapy, a form of radionuclide therapy for occluded coronary disease (restenosis). Monte Carlo code, MCNP4C, has been used to calculate the radiation dose from the encapsulated array of B-emitting seeds (Sr/Y-source train). Solid water phantoms have been fabricated to measure the dose on the radiochromic films that were expo… more
Date: June 25, 2002
Creator: Choi, Chan K.
Item Type: Refine your search to only Report
open access

Montezuma Creek Stability Evaluation at Site of Former Monticello Tailings Pile

Description: This report documents the results of an evaluation of stream stability for Montezuma Creek downstream of the former uranium and vanadium millsite at Monticello, Utah. The work was performed by personnel from Oak Ridge National Laboratory's (ORNL's) Environmental Technology Section (ETS). ORNL/ETS was the Independent Verification Contractor (IVC) for the Monticello projects, and it established independent verification strategies that provided the U.S. Department of Energy (DOE) with a third-part… more
Date: October 4, 2001
Creator: Korte, N.
Item Type: Refine your search to only Report
open access

The Monumental Task of Warning Future Generations

Description: Describing preliminary concepts for permanent warning monuments or markers on the mountain's surface will be part of the US Department of Energy's license application to the Nuclear Regulatory Commission (NRC) for a proposed repository at Yucca Mountain, Nevada. The NRC requires that the monuments or markers accurately identify the location of the repository, be designed to be as permanent as practicable and convey a warning against intrusion into the underground repository, because of risk to … more
Date: January 4, 2005
Item Type: Refine your search to only Report
open access

MOON for a next-generation neutrino-less double-beta decay experiment: Present status and perspective

Description: The performance of the MOON detector for a next-generation neutrino-less double-beta decay experiment was evaluated by means of the Monte Carlo method. The MOON detector was found to be a feasible solution for the future experiment to search for the Majorana neutrino mass in the range of 100-30 meV.
Date: January 1, 2008
Creator: Shima, T.; Doe, P. J.; Ejiri, H.; Elliot, S. R.; Engel, J.; Finger, M. et al.
Item Type: Refine your search to only Article
open access

MOOSE: A PARALLEL COMPUTATIONAL FRAMEWORK FOR COUPLED SYSTEMS OF NONLINEAR EQUATIONS.

Description: Systems of coupled, nonlinear partial di?erential equations often arise in sim- ulation of nuclear processes. MOOSE: Multiphysics Ob ject Oriented Simulation Environment, a parallel computational framework targeted at solving these systems is presented. As opposed to traditional data / ?ow oriented com- putational frameworks, MOOSE is instead founded on mathematics based on Jacobian-free Newton Krylov (JFNK). Utilizing the mathematical structure present in JFNK, physics are modularized into “Ke… more
Date: May 1, 2009
Creator: Hansen, G.; Newman, C. & Gaston, D.
Item Type: Refine your search to only Article
Back to Top of Screen