11 Matching Results

Search Results

Advanced search parameters have been applied.

Review and combination of experimental results for neutron emission per fission of /sup 232/Th. [1 to 16 MeV]

Description: An analysis was made of the existing experimental data for ..nu..-bar(E) of /sup 232/Th, the average number of neutrons emitted per fission of /sup 232/Th. This analysis suggests that a single linear function of the neutron energy describes the data within their uncertainties. The parameters of the linear function and their uncertainties are given. 1 figure, 5 tables.
Date: May 1, 1978
Creator: Gwin, R.
Partner: UNT Libraries Government Documents Department

Critical Assemblies of Uranium Metal

Description: Data on critical assemblies of fissionable uranium metals are summarized. Empirical studies are made for spccific reflectors and gcometrics to determine the fcasibility of extrapolating these data for conditions concerning nuclcear safcty problems. Also included are the influencs on critical systems by various reficctors, U-235 isotopic enrichment, density, and small metal pieces homogcncously distributed in water. (auth)
Date: March 26, 1959
Creator: Gwin, R. & Mee, W. T.
Partner: UNT Libraries Government Documents Department

STUDIES OF THE SCINTILLATION PROCESS IN CsI(Tl)

Description: The scintillation response of CsI(Tl) crystals, having various thallium contents, was measured for excitation of the crystals by monoenergetic gamma rays, protons, and alpha particles. The investi gation was made to provide a test of some of the features of a theoretical model of the scintillation process in thallium-activated alkali iodides proposed by Murray and Meyer. In order to insure that the results obtained in this program would provide a critical test of the scintillation model, special attention was paid to technical effects which could influence the interpretation of the experimental data. For example, the effect of the pulseanalysis time on the relative scintillation response of CsI(Tl) to various charged parti cles was investigated. In addition, the emission spectra of the CsI(Tl) crystals were measured for excitation by x rays, protons, and alpha particles. The results of the investigation showed that the scintillation efficiency of CsI(Tl) is a continuous function of dE/dx, as assumed in the scintillation model, within the accuracy of the experiments when the effect of delta ravs are considered. This led to the conclusion that the light output of CsI(Tl) crystals is, in general, a nonlinear function of the energy of the particle. The shape of the dL/dE versus dE/dx curve for CsI(Tl) crystals is shown to be nearly independent of the thallium content of the crystal. This is in distinct contrast to the predictions of the scinti llation model. An examination of the emission spectra of CsI(Tl) crystals showed that light is emitted in a band, centered at about 3300A, which is characteristic of the emission of the pure crystal, as well as the characteriatic thallium luminescence. The relative intensity of this luminescence with respect to the thallium- activator luminescence increases as the ionization density in the crystal increases and increases as the thallium content decreases. ...
Date: November 30, 1962
Creator: Gwin, R. & Murray, R.B.
Partner: UNT Libraries Government Documents Department

Measurement of the energy dependence of prompt fission neutron emission from /sup 233/U, /sup 235/U, and /sup 239/Pu for E = 0. 0005 to 10 MeV relative to emission from spontaneous fission of /sup 252/Cf

Description: A series of experiments has been performed to measure the dependence on the incident neutron energy of anti nu/sub p/(E), the average number of prompt neutrons emitted per fission, of /sup 233/U, /sup 235/U, and /sup 239/Pu relative to anti nu/sub p/ (/sup 252/Cf), the average number of prompt neutrons emitted in spontaneous fission of /sup 252/Cf. The incident energy range was 0.0005 to 10 MeV. A white neutron source was generated by the Oak Ridge Electron Linear Accelerator and the energies of the neutrons incident on the fissile samples were determined by time-of-flight techniques. The fissile sample and the /sup 252/Cf standard were contained in a fission chamber surrounded by a large volume (0.91 m/sup 3/) liquid scintillator loaded with gadolinium. Fissions were detected by the fission chamber and the neutrons were detected by the scintillator. The results for /sup 239/Pu agree over most of the energy range with the results of the evaluation of Manero and Konshin. However, the present results are larger for /sup 235/U than those of Manero and Konshin and for /sup 233/U the present data yield a different energy dependence in the interval 100 to 600 keV. Final results are displayed.
Date: January 1, 1985
Creator: Gwin, R.; Spencer, R.R. & Ingle, R.W.
Partner: UNT Libraries Government Documents Department

Measurement of the average number of prompt neutrons emitted per fission of /sup 235/U relative to /sup 252/Cf for the energy region 500 eV to 10 MeV

Description: The average number of prompt neutrons emitted per fission ..nu../sub p/-bar(E), was measured for /sup 235/U relative to ..nu../sub p/-bar for the spontaneous fission of /sup 252/Cf over the neutron energy range from 500 eV to 10 MeV. The samples of /sup 235/U and /sup 252/Cf were contained in fission chambers located in the center of a large liquid scintillator. Fission neutrons were detected by the large liquid scintillator. The present values of ..nu../sub p/-bar(E) for /sup 235/U are about 0.8% larger than those measured by Boldeman. In earlier work with the present system, it was noted that Boldeman's value of ..nu../sub p/-bar(E) for thermal energy neutrons was about 0.8% lower than obtained at ORELA. It is suggested that the thickness of the fission foil used in Boldeman's experiment may cause some of the discrepancy between his and the present values of ..nu../sub p/-bar(E). For the energy region up to 700 keV, the present values of ..nu../sub p/-bar(E) for /sup 235/U agree, within the uncertainty, with those given in ENDF/B-V. Above 1 MeV the present results for ..nu../sub p/-bar(E) range about the ENDF/B-V values with differences up to 1.3%. 6 figures, 1 table.
Date: January 1, 1980
Creator: Gwin, R.; Spencer, R.R.; Ingle, R.W.; Todd, J.H. & Weaver, H.
Partner: UNT Libraries Government Documents Department

Measurements of the average number of prompt neutrons emitted per fission of /sup 239/Pu and /sup 235/U. [0. 005 eV to 10 MeV]

Description: Measurements of the average number of prompt neutrons ..nu.. bar/sub p/(E) emitted in neutron-induced fission of /sup 235/U and /sup 239/Pu relative to ..nu.. bar/sub p/ for spontaneous fission of /sup 252/Cf were made over an incident neutron energy range from 0.005 eV to 10 MeV. The incident neutrons were generated in pulses at the Oak Ridge Electron Linear Accelerator, and their energies, defined by time-of-flight methods. The samples were contained in fission chambers located in a large liquid scintillator. Fissions in the samples were identified by the simultaneous detection of prompt fission gamma rays in the scintillator and a pulse from the fission chamber. Fission neutrons were identified by the detection of the prompt gamma-ray cascade resulting from neutron absorption in gadolinium loaded in the liquid scintillator. The value of ..nu.. bar/sub p/(E) for /sup 239/Pu at 0.0253 eV agrees with the value given in EDNF/B-IV, whereas the corresponding value for /sup 235/U is about 0.7% larger than that given in ENDF/B-IV. 4 figures, 4 tables.
Date: May 1, 1978
Creator: Gwin, R.; Spencer, R.R.; Ingle, R.W.; Todd, J.H. & Weaver, H.
Partner: UNT Libraries Government Documents Department

Measurement of α, the Ratio of the Neutron Capture Cross Section to the Fission Cross Section, for ²³⁵U in the Energy Region from 3.25 eV to 1.8 keV

Description: Report issued by the Oak Ridge National Laboratory discussing techniques to obtain measurements of alpha for enriched uranium. Descriptions of equipment and experiments used to obtain alpha are presented. This report includes tables, and illustrations.
Date: April 1965
Creator: deSussure, G.; Weston, L. W.; Gwin, R.; Russell, J. E. & Hockenbury, R. W.
Partner: UNT Libraries Government Documents Department