Author
John S. Hendricks
Other affiliations: Brookhaven National Laboratory
Bio: John S. Hendricks is an academic researcher from Los Alamos National Laboratory. The author has contributed to research in topics: Monte Carlo method & Hybrid Monte Carlo. The author has an hindex of 19, co-authored 58 publications receiving 2383 citations. Previous affiliations of John S. Hendricks include Brookhaven National Laboratory.
Papers published on a yearly basis
Papers
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TL;DR: High confidence in the MCNP6 code is based on its performance with the verification and validation test suites, comparisons to its predecessor codes, the regression test suite, its code development process, and the underlying high-quality nuclear and atomic databases.
Abstract: MCNP6 is simply and accurately described as the merger of MCNP5 and MCNPX capabilities, but it is much more than the sum of those two computer codes. MCNP6 is the result of five years of effort by ...
977 citations
Planetary Science Institute1, Johns Hopkins University Applied Physics Laboratory2, Smithsonian Institution3, University of Tennessee4, University of Toulouse5, United States Geological Survey6, Los Alamos National Laboratory7, Max Planck Society8, California Institute of Technology9, University of California, Los Angeles10
TL;DR: Analysis of data from the Dawn spacecraft implies that asteroid Vesta is rich in volatiles, and models of Vesta’s evolution based on studies of howardite, eucrite, and diogenite meteorites are tested, finding that global Fe/O and Fe/Si ratios are consistent with HED compositions.
Abstract: Using Dawn’s Gamma Ray and Neutron Detector, we tested models of Vesta’s evolution based on studies of howardite, eucrite, and diogenite (HED) meteorites. Global Fe/O and Fe/Si ratios are consistent with HED compositions. Neutron measurements confirm that a thick, diogenitic lower crust is exposed in the Rheasilvia basin, which is consistent with global magmatic differentiation. Vesta’s regolith contains substantial amounts of hydrogen. The highest hydrogen concentrations coincide with older, low-albedo regions near the equator, where water ice is unstable. The young, Rheasilvia basin contains the lowest concentrations. These observations are consistent with gradual accumulation of hydrogen by infall of carbonaceous chondrites—observed as clasts in some howardites—and subsequent removal or burial of this material by large impacts.
232 citations
TL;DR: The Gamma Ray and Neutron Detector (GRaND) was used in the NASA Dawn mission to map the surface elemental composition of Vesta and Ceres at regional spatial scales as mentioned in this paper, including the constituents of silicate and oxide minerals, ices, and products of volcanic exhalation and aqueous alteration.
Abstract: The NASA Dawn Mission will determine the surface composition of 4 Vesta and 1 Ceres, providing constraints on their formation and thermal evolution. The payload includes a Gamma Ray and Neutron Detector (GRaND), which will map the surface elemental composition at regional spatial scales. Target elements include the constituents of silicate and oxide minerals, ices, and the products of volcanic exhalation and aqueous alteration. At Vesta, GRaND will map the mixing ratio of end-members of the howardite, diogenite, and eucrite (HED) meteorites, determine relative proportions of plagioclase and mafic minerals, and search for compositions not well sampled by the meteorite collection. The large south polar impact basin may provide an opportunity to determine the composition of Vesta’s mantle and lower crust. At Ceres, GRaND will provide chemical information needed to test different models of Ceres’ origin and thermal and aqueous evolution. GRaND is also sensitive to hydrogen layering and can determine the equivalent H2O/OH content of near-surface hydrous minerals as well as the depth and water abundance of an ice table, which may provide information about the state of water in the interior of Ceres. Here, we document the design and performance of GRaND with sufficient detail to interpret flight data archived in the Planetary Data System, including two new sensor designs: an array of CdZnTe semiconductors for gamma ray spectroscopy, and a loaded-plastic phosphor sandwich for neutron spectroscopy. An overview of operations and a description of data acquired from launch up to Vesta approach is provided, including annealing of the CdZnTe sensors to remove radiation damage accrued during cruise. The instrument is calibrated using data acquired on the ground and in flight during a close flyby of Mars. Results of Mars flyby show that GRaND has ample sensitivity to meet science objectives at Vesta and Ceres. Strategies for data analysis are described and prospective results for Vesta are presented for different operational scenarios and compositional models.
180 citations
19 Mar 2007
TL;DR: MCNPX as mentioned in this paper is a general-purpose Monte Carlo radiation transport code with three-dimensional geometry and continuous energy transport of 34 particles and light ions, including neutrons, photons and electrons.
Abstract: MCNPX (Monte Carlo N‐Particle eXtended) is a general‐purpose Monte Carlo radiation transport code with three‐dimensional geometry and continuous‐energy transport of 34 particles and light ions It contains flexible source and tally options, interactive graphics, and support for both sequential and multi‐processing computer platforms MCNPX is based on MCNP4c and has been upgraded to most MCNP5 capabilities MCNP is a highly stable code tracking neutrons, photons and electrons, and using evaluated nuclear data libraries for low‐energy interaction probabilities MCNPX has extended this base to a comprehensive set of particles and light ions, with heavy ion transport in development Models have been included to calculate interaction probabilities when libraries are not available Recent additions focus on the time evolution of residual nuclei decay, allowing calculation of transmutation and delayed particle emission MCNPX is now a code of great dynamic range, and the excellent neutronics capabilities allow new opportunities to simulate devices of interest to experimental particle physics, particularly calorimetry This paper describes the capabilities of the current MCNPX version 26C, and also discusses ongoing code development
158 citations
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01 Jan 1993
TL;DR: In this article, the authors present a practical guide for the use of general-purpose Monte Carlo code MCNP, including several examples and a discussion of the particular techniques and the Monte Carlo method itself.
Abstract: This manual is a practical guide for the use of our general-purpose Monte Carlo code MCNP. The first chapter is a primer for the novice user. The second chapter describes the mathematics, data, physics, and Monte Carlo simulation found in MCNP. This discussion is not meant to be exhaustive---details of the particular techniques and of the Monte Carlo method itself will have to be found elsewhere. The third chapter shows the user how to prepare input for the code. The fourth chapter contains several examples, and the fifth chapter explains the output. The appendices show how to use MCNP on various computer systems and also give details about some of the code internals.
6,481 citations
01 Jan 1995
TL;DR: A Monte Carlo model of steady-state light transport in multi-layered tissues (MCML) has been coded in ANSI Standard C; therefore, the program can be used on various computers and has been in the public domain since 1992.
Abstract: A Monte Carlo model of steady-state light transport in multi-layered tissues (MCML) has been coded in ANSI Standard C; therefore, the program can be used on various computers. Dynamic data allocation is used for MCML, hence the number of tissue layers and grid elements of the grid system can be varied by users at run time. The coordinates of the simulated data for each grid element in the radial and angular directions are optimized. Some of the MCML computational results have been verified with those of other theories or other investigators. The program, including the source code, has been in the public domain since 1992.
2,889 citations
TL;DR: A Monte Carlo model of steady-state light transport in multi-layered tissues (MCML) has been coded in ANSI Standard C; therefore, the program can be used on various computers as mentioned in this paper.
2,678 citations
Los Alamos National Laboratory1, Brookhaven National Laboratory2, Oak Ridge National Laboratory3, Rensselaer Polytechnic Institute4, Argonne National Laboratory5, Lawrence Livermore National Laboratory6, International Atomic Energy Agency7, National Institute of Standards and Technology8, Japan Atomic Energy Agency9, Idaho National Laboratory10, Jožef Stefan Institute11, Nuclear Research and Consultancy Group12, University of Vienna13
TL;DR: The ENDF/B-VII.1 library as mentioned in this paper is the most widely used data set for nuclear data analysis and has been updated several times over the last five years. But the most recent version of the ENDF-B-VI.0 library is based on the JENDL-4.0 standard.
2,171 citations
Brookhaven National Laboratory1, Los Alamos National Laboratory2, International Atomic Energy Agency3, Rensselaer Polytechnic Institute4, National Institute of Standards and Technology5, Oak Ridge National Laboratory6, Argonne National Laboratory7, Lawrence Livermore National Laboratory8, Lawrence Berkeley National Laboratory9, North Carolina State University10, University of Michigan11, Institut de radioprotection et de sûreté nucléaire12, TRIUMF13, Rosatom14, Chalk River Laboratories15, Paul Scherrer Institute16, Karlsruhe Institute of Technology17, University of Bucharest18, Joint Institute for Nuclear Research19
TL;DR: The new ENDF/B-VIII.0 evaluated nuclear reaction data library as mentioned in this paper includes improved thermal neutron scattering data and uses new evaluated data from the CIELO project for neutron reactions on 1 H, 16 O, 56 Fe, 235 U, 238 U and 239 Pu described in companion papers.
1,249 citations