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Energy deposition by 45-GeV photons in H, Be, Al, Cu, and Ta

Description: Electron--photon cascade calculations have been carried out for zero- width beams of 45-GeV photons normally incident on semi-infinite slabs of hydrogen, beryllium, aluminum, copper, and tantalum. The energy deposition is given as a function of both depth and radius in the slabs. (auth)
Date: January 1, 1974
Creator: Alsmiller, R.G. Jr. & Barish, J.
Partner: UNT Libraries Government Documents Department

Coupled neutron--gamma multigroup--multitable cross sections for 29 materials pertinent to nuclear weapons effect calculations generated by LASL/TD Division

Description: This report lists 42-group, coupled, neutron -gamma cross sections for H, D, T, /sup 3/He, /sup 4/He, /sup 6/Li, /sup 7/Li, Be, /sup 10/B, /sup 11/B, C, N, O, Na, Mg, Ai, Si, Cl, A, K, Ca, Fe, Cu, W, Pb, /sup 235/U, /sup 238/U, / sup 239/Pu, and /sup 240/Pu. Most of these materials are used in nuclear- weaponseffects calculations, where the elements for air, ground, and sea water are needed. Further, lists are given of cross sections for materials used in nuclear weapons vulnerability calculations, such as the elements of high explosives as well as materials that will undergo fusion and fission. Most of the common reactor materials are also listed. The 42 coupled neutron-gamma groups are split into 30 neutron groups (17 MeV through 1.39 x 10/sup -4/ eV) and 12 gamma groups (10 MeV through 0.01 MeV). Data sources and averaging schemes used for the development of these multigroup parameters are given. (119 tables) (auth)
Date: February 1, 1974
Creator: Sandmeier, H.A.; Hansen, G.E.; Seamon, R.E.; Hirons, T.J. & Marshall, A.H.
Partner: UNT Libraries Government Documents Department

Preliminary cross-section sensitivity analysis for an air-over-ground environment

Description: Two-dimensional sensitivity calculations were made for an air-over- ground geometry to determine the effect of air and ground cross-section perturbations on the total neutron and gamma ray dose near the air/ground interface and 415 meters above the ground. ENDF/B 22 neutron and 18 gamma group Version IV cross-sections were used in all computations. (auth)
Date: January 1, 1976
Creator: Pace, J.V. III & Bartine, D.E.
Partner: UNT Libraries Government Documents Department

First study of nano-composite scintillators under alpha irradiation

Description: We demonstrate that nano-composite materials based on semiconductor quantum dots have great potential for radiation detection via scintillation. While quantum dots and laser dyes both emit in the visible range at room temperature, the Stokes shift of the dyes is significantly larger. The scintillation output of both systems was studied under alpha irradiation and interpreted using a combination of energy-loss and photon transport Monte Carlo simulation models. The comparison of the two systems, which allows the quantification of the role played by the Stokes shift in the scintillation output, opens up exciting possibilities for a new class of scintillators that would take advantage of the limitless assembly of nano-crystals in large, transparent, and sturdy matrices.
Date: June 1, 2005
Creator: Letant, S & Wang, T
Partner: UNT Libraries Government Documents Department

Piecewise linear discretization of Symbolic Implicit Monte Carlo radiation transport in the difference formulation

Description: We describe a Monte Carlo solution for time dependent photon transport, in the difference formulation with the material in local thermodynamic equilibrium (LTE), that is piecewise linear in its treatment of the material state variable. Our method employs a Galerkin solution for the material energy equation while using Symbolic Implicit Monte Carlo (SIMC) to solve the transport equation. In constructing the scheme, one has the freedom to choose between expanding the material temperature, or the equivalent black body radiation energy density at the material temperature, in terms of finite element basis functions. The former provides a linear treatment of the material energy while the latter provides a linear treatment of the radiative coupling between zones. Subject to the conditional use of a lumped material energy in the vicinity of strong gradients, possible with a linear treatment of the material energy, our approach provides a robust solution for time dependent transport of thermally emitted radiation that can address a wide range of problems. It produces accurate results in the diffusion limit.
Date: November 15, 2005
Creator: Brooks III, E D; Szoke, A & Peterson, J L
Partner: UNT Libraries Government Documents Department

EPDL97: the evaluated photo data library `97 version

Description: The Evaluated Photon Data Library, 1997 version (EPLD97), is designed for use in photon transport calculations at Lawrence Livermore National Laboratory. This library includes photon interaction data for all elements with atomic number between Z = 1 (hydrogne) and 100 (fermium), including: photoionization, photoexcitation, coherent and incoherent scattering, and pair and triplet porduction cross sections. For use in applications data is provided for all elements over the energy range 1 eV to 100 GeV. This report documents the sources and treatment of the data included inthis library. EPDL97 completely supersedes the earlier 1989 version of EPDL and it is highly recommended that useres only use the most recent version of this library.
Date: September 19, 1997
Creator: Cullen, D.E.; Hubbell, J.H. & Kissel, L.
Partner: UNT Libraries Government Documents Department

Angular quadratures for improved transport computations

Description: This paper introduces new octant-range, composite-type Gauss and mid-point rule angular quadrature formulas for neutron and photon transport computations. A generalization to octant-range quadratures is also introduced in order to allow for discontinuities at material interfaces for two- and three-dimensional transport problems which can be modeled with 60-degree triangular or hexagonal mesh subdivisions in the x-y plane.
Date: July 22, 1999
Creator: Abu-Shumays, I.K.
Partner: UNT Libraries Government Documents Department

Coupling 2-D cylindrical and 3-D x-y-z transport computations

Description: This paper describes a new two-dimensional (2-D) cylindrical geometry to three-dimensional (3-D) rectangular x-y-z splice option for multi-dimensional discrete ordinates solutions to the neutron (photon) transport equation. Of particular interest are the simple transformations developed and applied in order to carry out the required spatial and angular interpolations. The spatial interpolations are linear and equivalent to those applied elsewhere. The angular interpolations are based on a high order spherical harmonics representation of the angular flux. Advantages of the current angular interpolations over previous work are discussed. An application to an intricate streaming problem is provided to demonstrate the advantages of the new method for efficient and accurate prediction of particle behavior in complex geometries.
Date: June 30, 1998
Creator: Abu-Shumays, I.K.; Yehnert, C.E. & Pitcairn, T.N.
Partner: UNT Libraries Government Documents Department

ITS Version 4.0: Electron/photon Monte Carlo transport codes

Description: The current publicly released version of the Integrated TIGER Series (ITS), Version 3.0, has been widely distributed both domestically and internationally, and feedback has been very positive. This feedback as well as our own experience have convinced us to upgrade the system in order to honor specific user requests for new features and to implement other new features that will improve the physical accuracy of the system and permit additional variance reduction. This presentation we will focus on components of the upgrade that (1) improve the physical model, (2) provide new and extended capabilities to the three-dimensional combinatorial-geometry (CG) of the ACCEPT codes, and (3) permit significant variance reduction in an important class of radiation effects applications.
Date: July 1, 1995
Creator: Halbleib, J.A,; Kensek, R.P. & Seltzer, S.M.
Partner: UNT Libraries Government Documents Department

The MC21 Monte Carlo Transport Code

Description: MC21 is a new Monte Carlo neutron and photon transport code currently under joint development at the Knolls Atomic Power Laboratory and the Bettis Atomic Power Laboratory. MC21 is the Monte Carlo transport kernel of the broader Common Monte Carlo Design Tool (CMCDT), which is also currently under development. The vision for CMCDT is to provide an automated, computer-aided modeling and post-processing environment integrated with a Monte Carlo solver that is optimized for reactor analysis. CMCDT represents a strategy to push the Monte Carlo method beyond its traditional role as a benchmarking tool or ''tool of last resort'' and into a dominant design role. This paper describes various aspects of the code, including the neutron physics and nuclear data treatments, the geometry representation, and the tally and depletion capabilities.
Date: January 9, 2007
Creator: Sutton TM, Donovan TJ, Trumbull TH, Dobreff PS, Caro E, Griesheimer DP, Tyburski LJ, Carpenter DC, Joo H
Partner: UNT Libraries Government Documents Department

MCNP photon transport benchmarking calculations performed at SRP. Revision 1

Description: Monte Carlo methods have long been used at the Savannah River Laboratory (SRL) to perform criticality calculations for many different processes. To perform transport analyses (both neutron and photon) a two-dimensional infinite lattice integral transport code (GLASS) has been used. The neutron transport portion of the code has been benchmarked against other codes and experimental data. The photon transport portion of the code, which is used to calculate gamma redistribution in the event of a loss of moderator and/or coolant, had not been benchmarked against either. For this reason, the Monte Carlo code MCNP was used to benchmark the photon transport portion of the GLASS code. Preceding this, a brief description of the geometry of the Savannah River Plant`s (SRP) reactor cores and how they were modeled using MCNP will be given.
Date: 1989-06~
Creator: White, A. M.
Partner: UNT Libraries Government Documents Department

Program EPICP: Electron photon interaction code, photon test module. Version 94.2

Description: The computer code EPICP performs Monte Carlo photon transport calculations in a simple one zone cylindrical detector. Results include deposition within the detector, transmission, reflection and lateral leakage from the detector, as well as events and energy deposition as a function of the depth into the detector. EPICP is part of the EPIC (Electron Photon Interaction Code) system. EPICP is designed to perform both normal transport calculations and diagnostic calculations involving only photons, with the objective of developing optimum algorithms for later use in EPIC. The EPIC system includes other modules that are designed to develop optimum algorithms for later use in EPIC; this includes electron and positron transport (EPICE), neutron transport (EPICN), charged particle transport (EPICC), geometry (EPICG), source sampling (EPICS). This is a modular system that once optimized can be linked together to consider a wide variety of particles, geometries, sources, etc. By design EPICP only considers photon transport. In particular it does not consider electron transport so that later EPICP and EPICE can be used to quantitatively evaluate the importance of electron transport when starting from photon sources. In this report I will merely mention where we expect the results to significantly differ from those obtained considering only photon transport from that obtained using coupled electron-photon transport.
Date: September 1994
Creator: Cullen, D. E.
Partner: UNT Libraries Government Documents Department

Multidimensional electron-photon transport with standard discrete ordinates codes

Description: A method is described for generating electron cross sections that are compatible with standard discrete ordinates codes without modification. There are many advantages of using an established discrete ordinates solver, e.g. immediately available adjoint capability. Coupled electron-photon transport capability is needed for many applications, including the modeling of the response of electronics components to space and man-made radiation environments. The cross sections have been successfully used in the DORT, TWODANT and TORT discrete ordinates codes. The cross sections are shown to provide accurate and efficient solutions to certain multidimensional electronphoton transport problems.
Date: December 31, 1995
Creator: Drumm, C.R.
Partner: UNT Libraries Government Documents Department

Adjoint electron-photon transport Monte Carlo calculations with ITS

Description: A general adjoint coupled electron-photon Monte Carlo code for solving the Boltzmann-Fokker-Planck equation has recently been created. It is a modified version of ITS 3.0, a coupled electronphoton Monte Carlo code that has world-wide distribution. The applicability of the new code to radiation-interaction problems of the type found in space environments is demonstrated.
Date: February 1, 1995
Creator: Lorence, L.J.; Kensek, R.P.; Halbleib, J.A. & Morel, J.E.
Partner: UNT Libraries Government Documents Department

Monte Carlo simulation accuracy for calibrating germanium detector photon efficiency

Description: Over the past 30 years, Monte Carlo simulation of photons interacting with matter has gradually improved to the extent that it now appears suitable for calibrating germanium detectors for counting efficiency in gamma-ray spectral analysis. The process is particularly useful because it can be applied for a variety of source shapes and spatial relations between source and detector by simply redefining the geometry, whereas calibration with radioactive standards requires a separate set of measurements for each source shape and location relative to the detector. Simulation accuracy was evaluated for two large (126% and 110%) and one medium-sized (20%) detectors with radioactive point sources at distances of 10 m, 1.6 m, and 0.50 m and with aqueous solutions in a 0.5-L reentrant beaker and in jars of similar volume but various dimensions. The sensitivity in comparing measured and simulated results was limited by a combined uncertainty of about 3% in the radioactive standards and experimental conditions. Simulation was performed with the MCNP-4 code.
Date: August 1, 1997
Creator: Kamboj, Sunita & Kahn, B.
Partner: UNT Libraries Government Documents Department

ONEBFP development issues

Description: ONEBFP is a 1-D discrete-ordinates coupled electron-photon transport code that was recently developed to replace the ONELD code. The reasons for this replacement are explained in terms of a comparison of the programming structure and numerics of the two codes.
Date: October 1, 1996
Creator: Morel, J.E. & Walters, W.F.
Partner: UNT Libraries Government Documents Department

Multidimensional electron-photon transport with standard discrete ordinates codes

Description: A method is described for generating electron cross sections that are comparable with standard discrete ordinates codes without modification. There are many advantages of using an established discrete ordinates solver, e.g. immediately available adjoint capability. Coupled electron-photon transport capability is needed for many applications, including the modeling of the response of electronics components to space and man-made radiation environments. The cross sections have been successfully used in the DORT, TWODANT and TORT discrete ordinates codes. The cross sections are shown to provide accurate and efficient solutions to certain multidimensional electron-photon transport problems. The key to the method is a simultaneous solution of the continuous-slowing-down (CSD) portion and elastic-scattering portion of the scattering source by the Goudsmit-Saunderson theory. The resulting multigroup-Legendre cross sections are much smaller than the true scattering cross sections that they represent. Under certain conditions, the cross sections are guaranteed positive and converge with a low-order Legendre expansion.
Date: April 1, 1997
Creator: Drumm, C.R.
Partner: UNT Libraries Government Documents Department

A simplified spherical harmonic method for coupled electron-photon transport calculations

Description: In this thesis the author has developed a simplified spherical harmonic method (SP{sub N} method) and associated efficient solution techniques for 2-D multigroup electron-photon transport calculations. The SP{sub N} method has never before been applied to charged-particle transport. He has performed a first time Fourier analysis of the source iteration scheme and the P{sub 1} diffusion synthetic acceleration (DSA) scheme applied to the 2-D SP{sub N} equations. The theoretical analyses indicate that the source iteration and P{sub 1} DSA schemes are as effective for the 2-D SP{sub N} equations as for the 1-D S{sub N} equations. In addition, he has applied an angular multigrid acceleration scheme, and computationally demonstrated that it performs as well as for the 2-D SP{sub N} equations as for the 1-D S{sub N} equations. It has previously been shown for 1-D S{sub N} calculations that this scheme is much more effective than the DSA scheme when scattering is highly forward-peaked. The author has investigated the applicability of the SP{sub N} approximation to two different physical classes of problems: satellite electronics shielding from geomagnetically trapped electrons, and electron beam problems.
Date: December 1, 1997
Creator: Josef, J.A.
Partner: UNT Libraries Government Documents Department

Application of discrete ordinates and Monte Carlo methods to transport of photons from environmental sources

Description: Federal Guidance Report No. 12 tabulates dose coefficients for external exposure to photons and electrons emitted by radionuclides distributed in air, water, and soil. Although the dose coefficients of this report are based on previously developed dosimetric methodologies, they are derived from new, detailed calculations of energy and angular distributions of the radiations incident on the body and the transport of these radiations within the body. Effort was devoted to expanding the information available for assessment of radiation dose from radionuclides distributed on or below the surface of the ground. A companion paper (External Exposure to Radionuclides in Air, Water, and Soil) discusses the significance of the new tabulations of coefficients and provides detiled comparisons to previously published values. This paper discusses details of the photon transport calculations.
Date: April 1996
Creator: Ryman, J. C.; Eckerman, K. F.; Shultis, J. K.; Faw, R. E. & Dillman, L. T.
Partner: UNT Libraries Government Documents Department

Electron/Photon Verification Calculations Using MCNP4B

Description: MCNP4BW was released in February 1997 with significant enhancements to electron/photon transport methods. These enhancements have been verified against a wide range of published electron/photon experiments, spanning high energy bremsstrahlung production to electron transmission and reflection. The impact of several MCNP tally options and physics parameters was explored in detail. The agreement between experiment and simulation was usually within two standard deviations of the experimental and calculational errors. Furthermore, sub-step artifacts for bremsstrahlung production were shown to be mitigated. A detailed suite of electron depth dose calculations in water is also presented. Areas for future code development have also been explored and include the dependence of cell and detector tallies on different bremsstrahlung angular models and alternative variance reduction splitting schemes for bremsstrahlung production.
Date: April 1, 1999
Creator: Gierga, D. P. & Adams, K. J.
Partner: UNT Libraries Government Documents Department

Self-Adjoint Angular Flux Equation for Coupled Electron-Photon Transport

Description: Recently, Morel and McGhee described an alternate second-order form of the transport equation called the self adjoint angular flux (SAAF) equation that has the angular flux as its unknown. The SAAF formulation has all the advantages of the traditional even- and odd-parity self-adjoint equations, with the added advantages that it yields the full angular flux when it is numerically solved, it is significantly easier to implement reflective and reflective-like boundary conditions, and in the appropriate form it can be solved in void regions. The SAAF equation has the disadvantage that the angular domain is the full unit sphere and, like the even- and odd- parity form, S{sub n} source iteration cannot be implemented using the standard sweeping algorithm. Also, problems arise in pure scattering media. Morel and McGhee demonstrated the efficacy of the SAAF formulation for neutral particle transport. Here we apply the SAAF formulation to coupled electron-photon transport problems using multigroup cross-sections from the CEPXS code and S{sub n} discretization.
Date: July 8, 1999
Creator: Liscum-Powell, J. L.; Lorence, L. J., Jr.; Morel, J. E. & Prinja, A. K.
Partner: UNT Libraries Government Documents Department

Monte Carlo Particle Transport: Algorithm and Performance Overview

Description: Monte Carlo methods are frequently used for neutron and radiation transport. These methods have several advantages, such as relative ease of programming and dealing with complex meshes. Disadvantages include long run times and statistical noise. Monte Carlo photon transport calculations also often suffer from inaccuracies in matter temperature due to the lack of implicitness. In this paper we discuss the Monte Carlo algorithm as it is applied to neutron and photon transport, detail the differences between neutron and photon Monte Carlo, and give an overview of the ways the numerical method has been modified to deal with issues that arise in photon Monte Carlo simulations.
Date: June 2, 2005
Creator: Gentile, N; Procassini, R & Scott, H
Partner: UNT Libraries Government Documents Department