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in subjects: "Photoneutrons"

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Photodisintegration of /sup 3/H and /sup 3/He. [Threshold to 25 MeV]

The photoneutron cross sections for /sup 3/H and /sup 3/He have been measured from threshold to approx. 25 MeV with monoenergetic photons from the annihilation in flight of fast positrons at the LLL Electron-Positron Linear Accelerator facility. These reactions include the two-body breakup of /sup 3/H and the three-body breakup of both /sup 3/H and /sup 3/He; these measurements for /sup 3/H are the first to span the energy region across the peaks of the cross sections. An efficient BF/sub 3/-tu… more

Date: September 1, 1980

Creator: Faul, D.D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

NDA technology for uranium resource evaluation. Progress report July 1-December 31, 1979. [Gamma spectra calculations; field prototype photoneutron logging probe]

This report describes work performed during the time period from July 1, 1979 to December 31, 1979, on the contract for Nondestructive Nuclear Analysis (NDA) Technology for Uranium Resource Evaluation in Group Q-1. Calculational effort was focused on improving the accuracy with which detector response function maps can be generated for subsequent enfolding with ONETRAN angular flux data. Experimental effort was highlighted by a field test of the prototype photoneutron logging probe at the Grand… more

Date: August 1, 1980

Creator: Evans, M.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Electro- and photonuclear physics with polarized beams and targets

Two long-standing issues in photonuclear physics, the giant M1 resonance in Pb and deuteron photodisintegration, have been studied recently with polarized photons at Urbana and Frascati, respectively. The implications that this work has for settling these key issues will be discussed. In addition, the advantages of the internal polarized target method for electron scattering studies will be discussed and the technology of internal polarized target development will be reviewed. The first results… more

Date: January 1, 1987

Creator: Holt, R.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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NDA technology for uranium resource evaluation. Progress report, January 1-June 30, 1979

Calculational effort has focused on gamma-ray cross-section conversions, feasibility studies of an x-ray fluorescence (XRF) probe, and simulation of the prototype photoneutron logging tool. Experimental effort has concentrated on the design and fabrication of a field prototype photoneutron-based logging probe, on two types of borehole water monitors, and on a commercial pulse-shape discrimination unit to be used with the photoneutron logging probe. 37 figures, 4 tables.

Date: April 1, 1980

Creator: Evans, M.L. (comp.)

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Photoneutron logging system for direct uranium ore-grade determination

A prototype photoneutron probe for direct uranium assay in exploratory boreholes has been built and field tested. An approx. 10-Ci /sup 124/Sb gamma-ray source together with a beryllium converter is used to produce neutrons that diffuse into the surrounding formation and cause fissions in any /sup 235/U present. The fission neutrons that return to the probe are energy analyzed and counted by a high-pressure helium detector, thus indicating the concentration of uranium. The response of the probe… more

Date: June 1, 1982

Creator: Baker, M.P. & Marks, T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Photoneutron leakage from the W(. gamma. ,n) reaction at radiation therapy centers

The energy spectrum of photoneutrons from W(..gamma..,n) was observed for an electron energy of 10 MeV by using the ANL high-current electron linac and a neutron time-of-flight spectrometer.

Date: January 1, 1979

Creator: Holt, R.J.; Jackson, H.E. & Specht, J.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Coupled channels model for radiative capture of nucleons by /sup 12/C. [1 to 10 MeV]

A simple model based upon coupled-channels scattering calculations for nucleons on /sup 12/C was applied to the corresponding radiative capture reactions. It includes only electric dipole transitions via direct capture plus capture occurring via intermediate states consisting of only the 2/sup +/ first excited state of /sup 12/C coupled to a nucleon in the (s,d) shell. It is shown that the shape and magnitude of measured excitation functions of the /sup 12/C(p,..gamma../sub 0/) and /sup 13/C(..… more

Date: January 1, 1979

Creator: Johnson, D. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Atlas of photoneutron cross sections obtained with monoenergetic photons. Final edition, 1986

In view of the need for a comprehensive compilation of photoneutron cross-section data, these monoenergetic-photon data are gathered together here and presented in a uniform format. This compilation updates and supersedes the earlier editions of this Atlas. A more complete compilation is being assembled by the photonuclear group at the National Bureau of Standards. 15 refs., 174 figs.

Date: June 1, 1986

Creator: Dietrich, S.S. & Berman, B.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Neutron radiation from medical electron accelerators

A method is described using simple gold foils and relatively inexpensive moderators to measure neutron fluences, both fast nd thermal, which then can be converted to dose equivalent using a few simple formulas. The method is sensitive, easy to calibrate, and should work at most accelerators regardless of energy or room geometry.

Date: January 1, 1983

Creator: McCall, R.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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NDA technology for uranium resource evaluation. Progress report, January 1-June 30, 1980

This report describes work performed during the time period from January 1, 1980, to June 30, 1980, on the contract for Nondestructive Nuclear Analysis Technology for Uranium Resource Evaluation in the Safeguards Technology, International Safeguards, and Training Group, Q-1, at Los Alamos National Laboratory. The calculational effort was concentrated on the development of a generalized computer model to simulate the emission, transport, and detection of natural gamma radiation from various logg… more

Date: August 1, 1981

Creator: Evans, M.L. (comp.)

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Application of detailed fission-product decay gamma spectra in the calculation of photoneutron spectra from D(. gamma. ,n) reactions in PWR fuel

The magnitude, average neutron energy, and spectrum of the photoneutron source in a PWR fuel is calculated for shutdown times to 100 y using CINDER radionuclide inventory calculations, ENDF/B-V ..gamma.. line decay spectra, MCNP ..gamma.. transport calculations, and PHONEX D(..gamma..,n) reaction physics calculations.

Date: January 1, 1985

Creator: Wilson, W. B.; Stewart, J. E.; England, T. R. & Perry, R. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Evaluation of differential shim rod worth measurements in the Oak Ridge Research Reactor

Reasonable agreement between calculated and measured differential shim rod worths in the Oak Ridge Research Reactor (ORR) has been achieved by taking into account the combined effects of negative reactivity contributions from changing fuel-moderator temperatures and of delayed photoneutrons. A method has been developed for extracting the asymptotic period from the shape of the initial portion of the measured time-dependent neutron flux profile following a positive reactivity insertion. In this … more

Date: January 1, 1987

Creator: Bretscher, M.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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NDA technology for uranium resource evaluation. Progress report, July 1-December 31, 1978

The calculational work has focused on gamma-ray calculations, code improvements, and cross-section conversions. The experimental effort has concentrated on the design of a field prototype photoneutron logging probe and on uranium-fission neutron pulse-shape discrimination. The GAMRES code has been modified to provide the facility for computing gamma-ray response functions for different types of detectors. Calculations to identify the physical processes of importance in the operation of the dise… more

Date: November 1, 1979

Creator: Evans, M.L. (comp.)

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Photoneutron generation with electron undulators

An extremely compact line-geometry pulsed source of photoneutrons is proposed with controllable energies of only a few kiloelectron volts, average yields exceeding 1(13) per second, peak intensities higher than the average by two or three orders of magnitude, controllable polarization, and pulse durations of about 2 ns. This source uses photons from a magnetic undulator in a 30-GeV electron-storage ring. Parameters of the undulator and storage ring are stringent but probably attainable with car… more

Date: December 1, 1981

Creator: Baldwin, G.C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Personnel hazards from medical electron accelerator photoneutrons

For medical accelerators, neutron penetration through the room entry door is the major personnel hazard. Most therapy accelerator rooms are designed with at least a rudimentary maze to avoid the use of massive doors. Often, however, the maze may be similar to those shown in scale outline drawings of some medical electron accelerator rooms where the authors have made neutron measurements outside the doors which were of different thicknesses and compositions. The results are tabulated. It should … more

Date: December 1, 1979

Creator: McCall, R.C.; Jenkins, T.M.; Shore, R.A. & LaRiviere, P.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Plutonium well logging with the photoneutron uranium exploration system

The Los Alamos National Laboratory prototype photoneutron uranium exploration system was recently demonstrated at the Hanford site near Richland, Washington, for Rockwell-Hanford Operations (Rockwell). The demonstration determined the field performance capabilities of the uranium exploration system for in situ, downhole measurements of transuranic waste concentrations. The uranium exploration system is indeed capable of detecting plutonium in the test wells at the waste sites investigated. The … more

Date: September 1, 1982

Creator: Baker, M.P. & Marks, T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Locating giant resonances with photoneutrons

Recent studies of collective magnetic dipole resonances in heavy nuclei are reviewed with an emphasis on photoneutron experiments. In particular, the nuclear mass regions of 120, 140, and 208 are discussed in detail. New very-high-resolution photoneutron studies of /sup 208/Pb are presented. Applications of the photoneutron polarization method to the /sup 208/Pb(..gamma..,n/sub 0/)/sup 207/Pb and /sup 119/Sn(..gamma..,n/sub 0/)/sup 118/Sn reactions are reviewed. 12 figures, 2 tables)

Date: January 1, 1978

Creator: Holt, R.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Transport of accelerator produced neutrons in a concrete room

The production of photoneutrons by electron accelerators is an unavoidable process at operating energies above about 10 MeV. These photoneutrons create problems in shielding, personnel protection, and induced radioactivity. This paper attempts to describe the neutron field spectral and intensity distributions. The initial spectrum and modifying effects of photon shielding materials and concrete room shielding are considered. The relative yields of neutrons and photons as a function of the prima… more

Date: October 1, 1978

Creator: McCall, R. C.; Jenkins, T. M. & Shore, R. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Threshold photoneutron angular distribution and polarization studies of nuclei

The photoneutron method was applied to the study of: (1) deuteron photodisintegration; (2) giant magnetic dipole resonances in heavy nuclei; (3) mechanism of radiative capture in light nuclei; and (4) isospin splitting of the giant dipole resonance in /sup 60/Ni. These studies were performed with the pulsed bremsstrahlung beam and high-resolution spectrometer available at the Argonne high-current electron linac. A threshold photoneutron polarization method was developed in order to search for t… more

Date: January 1, 1980

Creator: Holt, R.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Neutron flux in K Reactor discharge area during operation

Based on the activation of gold foils in an hydrogeneous medium, the neutron flux incident on the rear wall of the discharge area of the KE reactor is estimated to be 6000 M/cm{sup 2} sec. The effective energy of the neutrons is estimated to be approximately 4 Mev. Neither of these values confirm order-of-magnitude estimates of the neutron flux and neutron energy expected to exist in the discharge area.

Date: June 19, 1959

Creator: Bunch, W. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Miniature neutron sources: Thermal neutron sources and their users in the academic field

The three levels of thermal neutron sources are introduced - University laboratory sources infrastructure sources and world-class sources - and the needs for each kind and their inter-dependence will be emphasized. A description of the possibilities for University sources based on {alpha}-Be reactions or spontaneous fission emission is given, and current experience with them is described. A new generation of infrastructure sources is needed to continue the regional programs based on small react… more

Date: September 1, 1992

Creator: Egelstaff, P. A. & Carpenter, J. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Search for Subthreshold Neutron Production in Be

We have searched for neutrons from the 3-body photon-induced reaction {sup 9}Be + {gamma} {yields} {alpha} + {alpha} + n using bremsstrahlung produced by electrons from a 2-MV Van de Graaff. The target was located within a block of beryllium surrounded by an array of {sup 3}He proportional counters embedded in paraffin. Based on energy and intensity calibrations of the accelerator and detector using the {sup 9}Be + {gamma} {yields} {sup 8}Be + n reaction, an upper limit of 93 nb (4{sigma}) was … more

Date: September 27, 2004

Creator: Chrien, R. E.; Alburger, D. E.; Sutter, R. J. & Wishart, J. F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Atlas of photoneutron cross sections obtained with monoenergetic photons

Photoneutron cross section data obtained with monoenergetic photons are presented in a uniform format. This compilation is current as of December, 1976.

Date: December 30, 1976

Creator: Berman, B. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Photoneutron effects on pulse reactor kinetics for the Annular Core Research Reactor (ACRR).

The Annular Core Research Reactor (ACRR) is a swimming-pool type pulsed reactor that maintains an epithermal neutron flux and a nine-inch diameter central dry cavity. One of its uses is neutron and gamma-ray irradiation damage studies on electronic components under transient reactor power conditions. In analyzing the experimental results, careful attention must be paid to the kinetics associated with the reactor to ensure that the transient behavior of the electronic device is understood. Since… more

Date: June 1, 2009

Creator: Parma, Edward J., Jr.

Item Type: Report

Partner: UNT Libraries Government Documents Department