Prettyman T.H.,Planetary Science Institute |
Feldman W.C.,Planetary Science Institute |
McSween Jr. H.Y.,University of Tennessee at Knoxville |
Dingler R.D.,Los Alamos National Laboratory |
And 7 more authors.
Space Science Reviews | Year: 2011
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 H 2O/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. © Springer Science+Business Media B.V. 2011. Source
Hendricks J.S.,TechSource, Inc. |
Hendricks J.S.,Los Alamos National Laboratory |
Hendricks J.S.,Brookhaven National Laboratory |
Quiter B.J.,University of California at Berkeley |
Quiter B.J.,Lawrence Berkeley National Laboratory
Nuclear Technology | Year: 2011
The angular distribution of scattered photons is incorrect in MCNPX and MCNP5 because the incoherent and coherent form factors are obsolete. The obsolete data affect all photon transport problems with E > 74 keV. Elastic backscatter for E > 105 keVis completely missing. Consequently, a new ACE-format photoatomic data library, tentatively named MCPLIB05 and referred to herein as MCPLIBOST, has been developed for MCNP/X. Data in MCPLIB05T other than form factors are identical to that in its predecessor photoatomic library, MCPLIB04. The new form factor data in MCPLIB05T come directly from ENDF/B-VI1(rev. O) andare in a format incompatible with older versions of MCNP/X. Consequently, a new version of MCNP/X has been developed to identify and use the new MCPLIB05T data and yet retain backward compatibility, including tracking, when MCPLIB04 is used. The NJOY nuclear data processing system is undergoing development to enable future generations of photoatomic data libraries with modern form factor data in the new format. Source
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.55K | Year: 2006
The non-scaling Fixed Focus Alternating Gradient (FFAG) Accelerator is of strong interest for DOE facilities and commercial applications as a less expensive, faster cycling, and more-readily-operable device. This project will investigate the feasibility of this concept and plan for the construction of a scaled electron prototype. Phase I will develop an optimum lattice design, which will be scaled to given high-energy applications and based on a beam dynamic assessment that uses analytical and particle tracking. A first-order magnet design, suitable to the electron prototype, will be developed. In Phase II, the magnet design will be refined, tested against performance in the lattice (beam dynamics, field errors, alignability, etc.), and a lattice cell will be constructed. The results should lead to eventual construction of the electron prototype in Phase III. Commercial Applications And Other Benefits as described by the Applicant: A simple economical accelerator should provide substantial benefits to the DOE in terms of the costs of constructing new accelerators and upgrading existing ones. Examples include an AGS beam-power upgrade, high-intensity proton drivers for nuclear physics, waste transmutation, radioisotope production, and high-intensity sychrotron radiation. In addition, the accelerator should have application to ion implantation, sterilization, and medical proton therapy
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.16K | Year: 2004
75153-Electron cloud effects are a critical technical risk for the next generation of high intensity proton and positron rings, to be used in facilities for High Energy Physics research. New diagnostics are required to observe electron cloud formation and trapping and to test theories and simulations of various beam dynamics issues. In particular, no such diagnostics have been developed for use in quadrupole magnets, where electron trapping is expected to play a large role. This project will undertake an analysis of the electron sweeping detector concept, in order to develop an optimized physics design for an electron cloud diagnostic for use in quadrupole magnets at high intensity proton or positron rings. In Phase I, a concept for an electron sweeping diagnostic for use in quadrupole magnets will be developed, various electron trajectories will be calculated, the physics design will be optimized, and engineering feasibility will be determined. In Phase II, a prototype will be engineered, fabricated and tested, and initial experimental data will be gathered at an existing facility, such as the Los Alamos Proton Storage Ring. Commercial Applications and Other Benefits as described by the awardee: The results of this project should directly benefit the high intensity proton and positron rings under construction or under active consideration. These include the Spallation Neutron Source, the Next Linear Collider, and Neutrino Factories.
Agency: Department of Defense | Branch: Missile Defense Agency | Program: STTR | Phase: Phase I | Award Amount: 99.31K | Year: 2005
We propose to study the development of a dedicated neutron source for Single Event Effects (SEE)to be collocated and intregrated with an existing neutron source (LENS)at the Indiana University Cyclotron Facility (IUCF). The study will maximize use of existing facilities to maximize the cost/benefit for the SEE neutron source.