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Effect of deformation and the neutron skin on RMS charge radii

Description: Droplet Model predictions for nuclear RMS charge radii are compared with measured values in order to determine whether or not there is any evidence for volume shell effects. After corrections for deformation, diffuseness, and the central depression have been applied, some evidence for such effects remains, but it is at about the same level as the experimental uncertainty.
Date: May 1, 1981
Creator: Myers, W. D. & Schmidt, K. H.
Partner: UNT Libraries Government Documents Department

Site inspections (SIs) under CERCLA. CERCLA Information Brief

Description: The US Environmental Protection Agency (EPA) revised the procedures for evaluating sites contaminated with hazardous substances and pollutants under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended by the Superfund Amendments and Reauthorization Act (SARA). Revised procedures include substantial changes to the Hazard Ranking System (HRS), the scoring system EPA uses to assess a site`s relative threat to human health and the environment and subsequent inclusion on the National Priorities List (NPL). A preliminary assessment (PA) is the first step in evaluating a site pursuant to CERCLA, the National Contingency Plan (NCP), and the HRS. Site inspection (SI) -- the second-step -- is conducted when the PA indicates that further investigation under CERCLA is needed. This Information Brief provides an overview of the SI process and its relationship to the HRS and other site activities under CERCLA and the Resource Conservation and Recovery Act (RCRA), and the information required to develop the HRS score for a site. A companion Information Brief provides an overview of the PA process.
Date: June 1, 1993
Creator: Schmidt, K.
Partner: UNT Libraries Government Documents Department

Preliminary assessments (PAs) under CERCLA. CERCLA Information Brief

Description: Section 105 of the Comprehensive Environmental Response, Compensation, and liability Act (CERCLA) required the Environmental Protection Agency (EPA) to establish criteria for determining priorities among releases or threatened releases of hazardous substances for the purpose of taking remedial action. EPA promulgated the Hazard Ranking System (HRS) for this purpose. In response to requirements of the Superfund Amendments and Reauthorization Act (SARA) the MRS has since been revised. The HRS is Appendix A to the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). A preliminary assessment (PA) is the first step in the process of evaluating a site potentially contaminated with hazardous substances or pollutants pursuant to CERCLA, the NCP, and the HRS. The purpose of the PA is to differentiate sites that pose no potential threat to human heath and the environment from sites that warrant further investigation under CERCLA.
Date: May 1, 1993
Creator: Schmidt, K.
Partner: UNT Libraries Government Documents Department

Nuclear-like states of quark matter

Description: In a world with only one flavor of light quark, QCD suggests that the low energy states of quark matter are similar to nuclei, but are not well represented as collections of baryons. Except for the existence of open nucleon channels, the same would be true for the actual, two-light-flavor world. 3 refs.
Date: January 1, 1986
Creator: Goldman, T.; Schmidt, K.E. & Stephenson, G.J. Jr.
Partner: UNT Libraries Government Documents Department

Multiquark interactions

Description: The conflict between the description of a field theory by its asymptotic states and the confinement of quarks in QCD is discussed. It is argued that a correct hadronic description of QCD (in terms of color singlets) may require very unusual vertex functions, despite the overlap of parts of the path integral with natural hadronic degrees-of-freedom. A formalism, which incorporates many of the advantages of an hadronic description into a quark picture, is described. Dibaryons are presented which show how well this approach illuminates the physics relevant to the multiquark problem. 14 refs., 1 fig., 5 tabs.
Date: January 1, 1988
Creator: Goldman, T.; Maltman, K.R.; Schmidt, K.E. & Stephenson, G.J. Jr.
Partner: UNT Libraries Government Documents Department

Damped and thermal motion of large, laser-aligned molecules in droplet beams

Description: We consider a monodispersed Rayleigh droplet beam of water droplets doped with proteins. An intense infrared laser is used to align these droplets. The arrangement has been proposed for electron and X-ray diffraction studies of proteins which are difficult to crystallize. This paper considers the effect of thermal fluctuations on the angular spread of alignment in thermal equilibrium, and relaxation phenomena, particularly the damping of oscillations excited as the molecules enter the field. The possibility of adiabatic alignment is also considered. We find that damping times in high pressure gas cell as used in X-ray diffraction experiments are short compared to the time taken for molecules to traverse the beam, and that a suitably shaped field might be used for electron diffraction experiments in vacuum to provide adiabatic alignment, thus obviating the need for a damping gas cell.
Date: September 29, 2005
Creator: Starodub, D; Doak, B; Schmidt, K; Weierstall, U; Wu, J; Spence, J et al.
Partner: UNT Libraries Government Documents Department

An example of system integration for RCRA policy analysis

Description: This paper describes the synthesis of various computer technologies and software systems used on a project to estimate the costs of remediating Solid Waste Management Units (SWMUs) that fall under the corrective action provisions of the Resource Conservation and Recovery Act (RCRA). The project used two databases collected by Research Triangle Institute (RTI) that contain information on SWMUs and a PC-based software system called CORA that develops cost estimates for remediating SWMUs. The project team developed rules to categorize every SWMU in the databases by the kinds of technologies required to clean them up. These results were input into CORA, which estimated costs associated with the technologies. Early on, several computing challenges presented themselves. First, the databases have several hundred thousand records each. Second, the categorization rules could not be written to cover all combinations of variables. Third, CORA is run interactively and the analysis plan called for running CORA tens of thousands of times. Fourth, large data transfers needed to take place between RTI and Oak Ridge National Laboratory. Solutions to these problems required systems integration. SWMU categorization was streamlined by using INTERNET as was the data transfer. SAS was used to create files used by a program called SuperKey that was used to run CORA. Because the analysis plan required the generation of hundreds of thousands of cost estimates, memory management software was needed to allow the portable IBM P70 to do the job. During the course of the project, several other software packages were used, including: SAS System for Personal Computers (SAS/PC), DBase III, LOTUS 1-2-3, PIZAZZ PLUS, LOTUS Freelance Plus, and Word Perfect. Only the comprehensive use of all available hardware and software resources allowed this project to be completed within the time and budget constraints. 5 refs., 3 figs., 3 tabs.
Date: January 1, 1991
Creator: Tonn, B.; Goeltz, R. (Oak Ridge National Lab., TN (USA)) & Schmidt, K. (Research Triangle Inst., Research Triangle Park, NC (USA))
Partner: UNT Libraries Government Documents Department

Monte Carlo approaches to effective field theories

Description: In this paper, we explore the application of continuum Monte Carlo methods to effective field theory models. Effective field theories, in this context, are those in which a Fock space decomposition of the state is useful. These problems arise both in nuclear and condensed matter physica. In nuclear physics, much work has been done on effective field theories of mesons and baryons. While the theories are not fundamental, they should be able to describe nuclear properties at low energy and momentum scales. After describing the methods, we solve two simple scalar field theory problems; the polaron and two nucleons interacting through scalar meson exchange. The methods presented here are rather straightforward extensions of methods used to solve quantum mechanics problems. Monte Carlo methods are used to avoid the truncation inherent in a Tamm-Dancoff approach and its associated difficulties. Nevertheless, the methods will be most valuable when the Fock space decomposition of the states is useful. Hence, while they are not intended for ab initio studies of QCD, they may prove valuable in studies of light nuclei, or for systems of interacting electrons and phonons. In these problems a Fock space decomposition can be used to reduce the number of degrees of freedom and to retain the rotational symmetries exactly. The problems we address here are comparatively simple, but offer useful initial tests of the method. We present results for the polaron and two non-relativistic nucleons interacting through scalar meson exchange. In each case, it is possible to integrate out the boson degrees of freedom exactly, and obtain a retarded form of the action that depends only upon the fermion paths. Here we keep the explicit bosons, though, since we would like to retain information about the boson components of the states and it will be necessary to keep these components ...
Date: January 1, 1991
Creator: Carlson, J. (Los Alamos National Lab., NM (United States)) & Schmidt, K.E. (Arizona State Univ., Tempe, AZ (United States). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

Dose, exposure time, and resolution in Serial X-ray Crystallography

Description: Using detailed simulation and analytical models, the exposure time is estimated for serial crystallography, where hydrated laser-aligned proteins are sprayed across a continuous synchrotron beam. The resolution of X-ray diffraction microscopy is limited by the maximum dose that can be delivered prior to sample damage. In the proposed Serial Crystallography method, the damage problem is addressed by distributing the total dose over many identical hydrated macromolecules running continuously in a single-file train across a continuous X-ray beam, and resolution is then limited only by the available fluxes of molecules and X-rays. Orientation of the diffracting molecules is achieved by laser alignment. We evaluate the incident X-ray fluence (energy/area) required to obtain a given resolution from (1) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (2) explicit simulation of diffraction patterns for a GroEL-GroES protein complex, and (3) the frequency cut off of the transfer function following iterative solution of the phase problem, and reconstruction of a density map in the projection approximation. These calculations include counting shot noise and multiple starts of the phasing algorithm. The results indicate the number of proteins needed within the beam at any instant for a given resolution and X-ray flux. We confirm an inverse fourth power dependence of exposure time on resolution, with important implications for all coherent X-ray imaging. We find that multiple single-file protein beams will be needed for sub-nanometer resolution on current third generation synchrotrons, but not on fourth generation designs, where reconstruction of secondary protein structure at a resolution of 7 {angstrom} should be possible with short (below 100 s) exposures.
Date: March 22, 2007
Creator: Starodub, D; Rez, P; Hembree, G; Howells, M; Shapiro, D; Chapman, H N et al.
Partner: UNT Libraries Government Documents Department

Test E3 on High-Energy Transient Meltdown of Irradiated UO₂ in a TREAT Mark-II Loop

Description: Three ''gassy'' irradiated uranium dioxide pins were run past failure in a 35-ms natural TREAT transient in TREAT loop Test E3 to guide in choosing between two modeling assumptions regarding energy conversion from sodium vaporization in an irradiated-oxide-fuel/coolant interaction (FCI): (1) The trapped fission gas enhances fuel fragmentation upon failure, accelerates fuel-coolant mixing, and thus promotes an energetic FCI, or, conversely, (2) the trapped fission gas blankets the fuel and reduces the rate of heat transfer to sodium, preventing an energetic FCI.
Date: December 1977
Creator: Deitrich, L. W.; Dickerman, C. E.; Willis, F. L.; Purviance, R. T.; Schmidt, K. J.; Agrawal, A. K. et al.
Partner: UNT Libraries Government Documents Department