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Nuclear astrophysics at the Holifield Radioactive Ion Beam Facility

Description: The potential for understanding spectacular stellar explosions such as novae, supernovae, and X-ray bursts will be greatly enhanced by the availability of the low-energy, high-intensity, accelerated beams of proton-rich radioactive nuclei currently being developed at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory. These beams will be utilized in absolute cross section measurements of crucial (p, {gamma}) capture reactions in efforts to resolve the substantial qualitative uncertainties in current models of explosive stellar hydrogen burning outbursts. Details of the nuclear astrophysics research program with the unique HRIBF radioactive beams and a dedicated experimental endstation--centered on the Daresbury Recoil Separator--will be presented.
Date: December 31, 1994
Creator: Smith, M.S.
Partner: UNT Libraries Government Documents Department

Nuclear astrophysics and the Daresbury Recoil Separator at the Holifield Radioactive Ion Beam Facility

Description: The Daresbury Recoil Separator (DRS) has been installed for nuclear astrophysics research at Oak Ridge National Laboratory`s Holifield Radioactive Ion Beam Facility. It will be used for direct measurements of capture reactions on radioactive ions which occur in stellar explosions such as novae, supernovae and X-ray bursts. These measurements will be made in inverse kinematics with radioactive heavy ion beams incident on hydrogen and helium targets, and the DRS will separate the capture reaction recoils from the intense flux of beam particles. Details of the new DRS experimental equipment and preliminary results from the first commissioning experiments with stable beams are described, along with the plans for the first measurements with radioactive beams. Other astrophysics research efforts at ORNL--in theoretical astrophysics, nuclear astrophysics data evaluation, heavy element nucleosynthesis, theoretical atomic astrophysics, and atomic astrophysics data--are also briefly described.
Date: December 1, 1997
Creator: Smith, M.S.
Partner: UNT Libraries Government Documents Department

US nuclear reaction data program in support of basic research

Description: Information about the US Nuclear Reaction Data Network (USNRDN) such as its members, work in progress, summaries of meetings, and organizational details may be found in its WWW Homepage. This paper is an overview of the data support provided by the network for basic research in nuclear astrophysics, radioactive ion beams, high energy heavy-ion and electron interactions and related activities involving all aspects of data stewardship.
Date: June 1997
Creator: Bhat, M.R.; Chadwick, M. B. & Smith, M. S.
Partner: UNT Libraries Government Documents Department

U.S. nuclear reaction data program in support of basic research

Description: Information about the US Nuclear Reaction Data Network (USNRDN) such as its members, work in progress, summaries of meetings, and organizational details may be found in its WWW Homepage. This paper is an overview of the data support provided by the network for basic research in nuclear astrophysics, radioactive ion beams, high energy heavy ion and electron interactions and related activities involving all aspects of data stewardship.
Date: March 1, 1998
Creator: Bhat, M.R.; Chadwick, M.B. & Smith, M.S.
Partner: UNT Libraries Government Documents Department

Commissioning of the Daresbury Recoil Separator for nuclear astrophysics measurements at the Holifield Radioactive Ion Beam Facility

Description: The Daresbury Recoil Separator (DRS) has been installed for nuclear astrophysics research at Oak Ridge National Laboratory`s Holifield Radioactive Ion Beam Facility. it will be used for direct measurements of capture reactions on radioactive ions which occur in stellar explosions such as novae and X-ray bursts. The physics motivation and plans for the first measurements with radioactive beams are described, and details of the new DRS experimental equipment and preliminary results from the first commissioning experiments with stable beams are given.
Date: December 1, 1997
Creator: Smith, M. S.; Blackmon, J. C. & Koehler, P. E.
Partner: UNT Libraries Government Documents Department

(Centralized reliability data organization for liquid metal reactor components)

Description: The Centralized Reliability Data Organization is a data bank and data analysis center, focusing on reliability, availability, and maintainability (RAM) data for components (e.g., valves, pumps, etc.) operating in liquid metal reactors and test facilities. PNC staff are using the CREDO data base as a resource for their development of a probabilistic safety assessment (PSA) for the MONJU fast breeder reactor now under construction. The meeting was held to discuss: (a) progress in FY 1989, (b) resolution of data base deficiencies and inconsistencies, (c) clarification of definitions for failure mode and failure cause, (d) component boundary definitions, (e) goals and objectives for the remainder of the fiscal year, and (f) proposals for future work. General agreement was reached on the need for improvements to the data base: resolution of data deficiencies and inconsistencies, reduction of the number of failure modes and causes, inclusion of failure severity, and a specific delineation of the boundary for each of the generic components. A schedule will be provided to PNC by 1 March 1991 addressing these issues. A proposal to develop a hybrid mainframe/PC reliability data base to improve user access was declined. A second proposal to develop a reliability data base for PNC's nuclear fuel reprocessing facilities was met with a request for more information. A formal proposal will be forwarded to PNC in the near future.
Date: February 7, 1991
Creator: Smith, M.S. & Manneschmidt, J.F.
Partner: UNT Libraries Government Documents Department

Accident assessment: role of the containment radiation monitor

Description: The containment radiation monitor may provide information to a power reactor operator that can aid assessment of the degree of core damage following a loss-of-coolant accident (LOCA). This paper reports calculations of the exposure rates that would exist in the containment of a commercial pressurized water reactor (PWR) following severe reactor transients. The results indicate exposure rates of 1 to 2 R . h/sup -1/ 30 minutes after a large LOCA, 4 to 5 x 10 R . h/sup -1/ one hour following a release of the gap activity, and 4 . 10/sup 6/ R . h/sup -1/ two hours after a transient that resulted in a fuel melt. Furthermore, differences between the energy spectra of photons released by noble gases and halogens suggest that containment radiation monitors may be designed to differentiate between these radioelements. The calculated exposure rates are not in agreement with the response of containment radiation monitors during the incident at the Crystal River Reactor. Inhomogeneous source terms, the operation of containment building systems, and inaccuracies in release estimates, measurements and calculations may have contributed to this discrepancy in one degree or another.
Date: January 1, 1980
Creator: Desrosiers, A. E.; Scherpelz, R. I.; Smith, M. S. & Grimes, B. K.
Partner: UNT Libraries Government Documents Department

Deterministic transport calculations of dose profiles due to proton beam irradiation

Description: Charged-particle transport calculations are most often carried out using the Monte Carlo technique. For example, the TIGER and EGS codes are used for electron transport calculations, while HETC models the transport of protons and heavy ions. In recent years there has been considerable progress in deterministic models of electron transport. Many of these models are also applicable to protons. In this paper we present discrete ordinates solutions to the Spencer-Lewis equation for protons. In its present form, our code calculates the energy deposition profile and primary proton flux in x-y geometry due to proton beam irradiation. Proton energies up to 0.4 GeV are permissible.
Date: January 1, 1988
Creator: Filippone, W.L.; Smith, M.S.; Santoro, R.T.; Gabriel, T.A. & Alsmiller, R.G. Jr.
Partner: UNT Libraries Government Documents Department

Nuclear astrophysics data at ORNL

Description: There is a new program of evaluation and dissemination of nuclear data of critical importance for nuclear astrophysics within the Physics Division of Oak Ridge National Laboratory. Recent activities include determining the rates of the important {sup 14}O({alpha},p){sup 17} F and {sup 17}F(p,{gamma}) {sup 18}Ne reactions, disseminating the Caughlan and Fowler reaction rate compilation on the World Wide Web, and evaluating the {sup 17}O(p,{alpha}){sup 14}N reaction rate. These projects, which are closely coupled to current ORNL nuclear astrophysics research, are briefly discussed along with future plans.
Date: November 1, 1998
Creator: Smith, M.S.; Blackmon, J.C.; Bardayan, D.W. & Ma, Z.
Partner: UNT Libraries Government Documents Department

First on-line results for As and F beams from HRIBF target/ion sources

Description: The first on-line tests of the ion sources to provide radioactive ion beams of {sup 69,70}As and {sup 17,18}F for the Holifield Radioactive Ion Beam Facility (HRIBF) have been performed using the UNISOR facility at HRIBF. The target/ion source is an electron beam plasma (EBP) source similar to the ISOLDE design. The measured efficiencies for {sup 69}As and {sup 70}AS were 0.5 {+-} 0.2% and 0.8 {+-} 0.3%, respectively. The arsenic hold-up time in the tested target ion source was 3.6 {+-} 0.3 hours as measured with {sup 72}As at a target temperature of 1300 {degrees}C. The measured efficiencies for {sup 17}F and {sup 18}F were 0.0052 {+-} 0.0008% and 0.06 {+-} 0.02%, respectively. The source hold-up time for fluorine was measured with Al{sup 18}F since 88% of the observed radioactive fluorine was found in this molecule. The Al{sup 18}F hold-up time was 16.4 {+-} 0.8 minutes at a target temperature of 1470 {degrees}C.
Date: December 31, 1996
Creator: Stracener, D.W.; Carter, H.K.; Kormicki, J.; Breitenbach, J.B.; Blackmon, J.C.; Smith, M.S. et al.
Partner: UNT Libraries Government Documents Department

New neutron capture and transmission measurements for {sup 134,136}Ba at ORELA and their impact on s-process nucleosynthesis calculations

Description: We have made high-resolution neutron capture and transmission measurements on isotopically enriched samples of {sup 134}Ba and {sup 136}Ba at the Oak Ridge Electron Linear Accelerator (ORELA) in the energy range from 20 eV to 500 keV. Previous measurements had a lower energy limit of 3 - 5 keV, which is too high to determine accurately the Maxwellian-averaged capture cross section at the low temperatures (kT {approx} 6 - 12 keV) favored by the most recent stellar models of the {ital s}-process. Our results for the astrophysical reaction rates are in good agreement with the most recent previous measurement at the classical {ital s}-process temperature, kT = 30 keV, but show significant differences at lower 40 temperatures. We discuss the astrophysical implications of these differences.
Date: October 1, 1996
Creator: Koehler, P.E.; Spencer, R.R.; Winters, R.R.; Guber, K.H.; Harvey, J.A.; Hill, N.W. et al.
Partner: UNT Libraries Government Documents Department

First on-line results for As and F beams from HRIBF target/ion sources

Description: The first on-line tests of the ion sources to provide radioactive ion beams of {sup 69,70}As and {sup 17,18}F for the Holifield Radioactive Ion Beam Facility have been performed using the UNISOR facility at HRIBF. For {sup 70}As the measured efficiency is 0.8 {+-} 0.3% with a hold-up time of 3.6 {+-} 0.3 hours as measured with {sup 72}As at a target temperature of 1,270 C. For {sup 17}F the efficiency for Al{sup 17}F is 0.0024 {+-} 0.0008% with a hold-up time of 16.4 {+-} 0.8 m as measured with Al{sup 18}F at a target temperature of 1,470 C.
Date: December 31, 1996
Creator: Carter, H.K.; Kormicki, J.; Stracener, D.W.; Breitenbach, J.B.; Blackmon, J.C.; Smith, M.S. et al.
Partner: UNT Libraries Government Documents Department

Nuclear Data Project Evaluation Activity Report

Description: This report summarizes the activities of the ORNL Nuclear Data Project since the IAEA Advisory Group meeting in October 1996. The group's future plans are also included.
Date: December 14, 1998
Creator: Akovali, Y.A.; Artna-Cohen, A.; Blackmon, J.C.; Radford, D.; Smith, M.S. & Yu, C.-H.
Partner: UNT Libraries Government Documents Department

Recent Nuclear Astrophysics Data Activities in the US

Description: Measurements in nuclear physics laboratories form the empirical foundation for new, realistic, sophisticated theoretical models of a wide variety of astrophysical systems. The predictive power of these models has, in many instances, a strong dependence on the input nuclear data, and more extensive and accurate nuclear data is required for these models than ever before. Progress in astrophysics can be aided by providing scientists with more usable, accurate, and significant amounts of nuclear data in a timely fashion in formats that can be easily incorporated into their models. A number of recent data compilations, evaluations, calculations, and disseminations that address nuclear astrophysics data needs will be described.
Date: August 30, 1999
Creator: Bardayan, D.W.; Blackmon, J.C.; Browne, E.; Firestone, R.B.; Hale, G.M.; Hoffman, R.D. et al.
Partner: UNT Libraries Government Documents Department