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in subjects: "Thermal Neutrons"

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The Advanced Neutron Source

The Advanced Neutron Source (ANS) is a new user experimental facility planned to be operational at Oak Ridge in the late 1990's. The centerpiece of the ANS will be a steady-state research reactor of unprecedented thermal neutron flux ({phi}{sub th} {approx} 9{center dot}10{sup 19} m{sup -2}{center dot}s{sup -1}) accompanied by extensive and comprehensive equipment and facilities for neutron-based research. 5 refs., 5 figs.

Date: January 1, 1989

Creator: Hayter, J. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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High-sensitivity transuranic waste assay by simultaneous proton and thermal-neutron interrogation using an electron linear accelerator

Simultaneous photon and neutron interrogation from electron linear accelerator pulses is used as the basis for a unique assay technique for transuranics. Both prompt and delayed neutrons from the induced fissions are counted on a single detection system, and the contributions from each interrogating flux are resolved. Detection limits (3 sigma) for /sup 239/Pu were estimated to be 3 mg for prompt fission neutrons and 6 mg for delayed neutrons. The technique also provides a clear distinction bet… more

Date: January 1, 1982

Creator: Franks, L. A.; Pigg, J. L.; Caldwell, J. T.; Cates, M. R.; Kunz, W. E. & Noel, B. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fission-product energy release for times following thermal-neutron fission of /sup 235/U between 2 and 14000 seconds

Fission-product decay energy-releases rates were measured for thermal-neutron fission of /sup 235/U. Samples of mass 1 to 10 ..mu..g were irradiated for 1 to 100 sec by use of the fast pneumatic-tube facility at the Oak Ridge Research Reactor. The resulting beta- and gamma-ray emissions were counted for times-after-fission between 2 and 14,000 seconds. The data were obtained for beta and gamma rays separately as spectral distributions, N(E/sub ..gamma../) vs E/sub ..gamma../ and N(E/sub beta/) … more

Date: October 1, 1977

Creator: Dickens, J. K.; Emery, J. F.; Love, T. A.; McConnell, J. W.; Northcutt, K. J.; Peelle, R. W. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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FITPULS: a code for obtaining analytic fits to aggregate fission-product decay-energy spectra. [In FORTRAN]

The operation and input to the FITPULS code, recently updated to utilize interactive graphics, are described. The code is designed to retrieve data from a library containing aggregate fine-group spectra (150 energy groups) from fission products, collapse the data to few groups (up to 25), and fit the resulting spectra along the cooling time axis with a linear combination of exponential functions. Also given in this report are useful results for aggregate gamma and beta spectra from the decay of… more

Date: March 1, 1980

Creator: LaBauve, R. J.; George, D. C. & England, T. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Accelerator technology for Los Alamos nuclear-waste-transmutation and energy-production concepts

Powerful proton linacs are being studied at Los Alamos as drivers for high-flux neutron sources that can transmute long-lived fission products and actinides in defense nuclear waste, and also as drivers of advanced fission-energy systems that could generate electric power with no long-term waste legacy. A transmuter fed by an 800-MeV, 140-mA cw conventional copper linac could destroy the accumulated {sup 99}Tc and {sup 129}I at the DOE's Hanford site within 30 years. A high-efficiency 1200-MeV,… more

Date: January 1, 1991

Creator: Lawrence, G. P.; Jameson, R. A. & Schriber, S. O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Shift-register coincidence electronics system for thermal neutron counters

An improved shift-register, coincidence-counting logic circuit, developed for use with thermal neutron well counters, is described in detail. A distinguishing feature of the circuit is its ability to operate usefully at neutron counting rates of several hundred kHz. A portable electronics package incorporating the new coincidence logic and support circuits is also described.

Date: April 1, 1980

Creator: Swansen, J.E.; Collinsworth, P.R. & Krick, M.S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Birdcage neutron coincidence counter manual

A thermal neutron coincidence counter has been constructed for the assay of fast critical assembly fuel plates stored in birdcages. Standard coincidence counting electronics are used. This manual describes the birdcage, the measurement system, and its performance characteristics. 3 refs.

Date: July 1, 1985

Creator: Krick, M. S.; Menlove, H. O. & Ramalho, A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Channel coincidence counter: version 1

A thermal neutron coincidence counter has been designed for the assay of fast critical assembly fuel drawers and plutonium-bearing fuel rods. The principal feature of the detector is a 7-cm by 7-cm by 97-cm detector channel, which provides a uniform neutron detection efficiency of 16% along the central 40 cm of the channel. The electronics system is identical to that used for the High-Level Neutron Coincidence Counter.

Date: June 1, 1980

Creator: Krick, M. S. & Menlove, H. O.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Slow neutron leakage spectra from spallation neutron sources

An efficient technique is described for Monte Carlo simulation of neutron beam spectra from target-moderator-reflector assemblies typical of pulsed spallation neutron sources. The technique involves the scoring of the transport-theoretical probability that a neutron will emerge from the moderator surface in the direction of interest, at each collision. An angle-biasing probability is also introduced which further enhances efficiency in simple problems. These modifications were introduced into t… more

Date: February 1, 1980

Creator: Das, S.G.; Carpenter, J.M. & Prael, R.E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Neutron total cross section of /sup 233/U from 0. 01 to 1. 0 eV

The neutron total cross section of /sup 233/U from 0.01 to 1.0 eV was measured at ORELA using a repetition rate of 25 sec/sup -1/ and a 17.872-meter flight path. Two samples of /sup 233/U enriched to 99.76% with inverse thicknesses of 165.2 and 321.1 barns/atom were measured. The data were corrected for neutron and gamma ray backgrounds which were less than or equal to 1%. Results from the two samples are in good agreement. The data are compared to earlier data and to ENDF/B-V evaluation.

Date: January 1, 1979

Creator: Harvey, J.A.; Moore, C.L. & Hill, N.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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A new concept for accelerator driven transmutation of nuclear wastes

A new concept for an accelerator-driven transmutation system is described. The central feature of the concept is generation of intense fluxes of thermal neutrons. In the system all long-lived radionuclides comprising high-level nuclear waste can be transmuted efficiently. Transmutation takes place in a unique, low material inventory environment. Presently two principal areas are being investigated for application of the concept. The first is associated with cleanup of defense high-level waste a… more

Date: January 1, 1991

Creator: Arthur, E. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Non-destructive field measurement of the ratio /sup 235/U//sup 238/U in depleted to moderately enriched uranium

The exploration of a natural reactor site is expedited by prompt measurement of /sup 235/U to /sup 238/U ratios near the mining operation. An instrument has been constructed which uses the relative fission rates of /sup 235/U and /sup 238/U in fast and moderated neutron spectra to measure the isotopic ratio. This device can be placed in the field and allows continuous monitoring of ore as a rich deposit of uranium is mined. With rapid return of isotopic information to the operator it is possibl… more

Date: January 1, 1977

Creator: Balagna, J.P. & Cowan, G.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Energy dependence of the /sup 238/U thermal capture cross section. [25 to 450/sup 0/C]

Integral activation measurements supported the thermal neutron energy dependence of /sup 238/U assumed in the ENDF/B-IV evaluation. The activation measurements were conducted in a thermally insulated graphite block at the side of the SP Reactor. The block was thermally heated to temperatures up to 450/sup 0/C. In addition to heating, gasolinium filters were used to tailor the neutron spectra incident on the foils. The metallic foils consisted of copper and depleted uranium. Copper served as the… more

Date: January 1, 1980

Creator: Baumann, N.P. & Owais, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Body composition to climate change studies - the many facets of neutron induced prompt gamma-ray analysis

In-vivo body composition analysis of humans and animals and in-situ analysis of soil using fast neutron inelastic scattering and thermal neutron capture induced prompt-gamma rays have been described. By measuring carbon (C), nitrogen (N) and oxygen (O), protein, fat and water are determined. C determination in soil has become important for understanding below ground carbon sequestration process in the light of climate change studies. Various neutron sources ranging from radio isotopic to compac… more

Date: November 17, 2008

Creator: Mitra, S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Production of Endohedral Fullerenes by Ion Implantation

The empty interior cavity of fullerenes has long been touted for containment of radionuclides during in vivo transport, during radioimmunotherapy (RIT) and radioimaging for example. As the chemistry required to open a hole in fullerene is complex and exceedingly unlikely to occur in vivo, and conformational stability of the fullerene cage is absolute, atoms trapped within fullerenes can only be released during extremely energetic events. Encapsulating radionuclides in fullerenes could therefore… more

Date: May 31, 2007

Creator: Diener, Michael D.; Alford, J. Michael & Mirzadeh, Saed

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Thermal neutron imaging support with other laboratories BL06-IM-TNI

The goals of this project are: (1) detect and locate a source of thermal neutrons; (2) distinguish a localized source from uniform background; (3) show shape and size of thermalizing material; (4) test thermal neutron imager in active interrogation environment; and (5) distinguish delayed neutrons from prompt neutrons.

Date: June 17, 2008

Creator: Vanier, P. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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High-Efficiency Thin-Film-Coated Semiconductor Neutron Detectors for Active Dosimetry Monitors

To develop a compact high-detection-efficiency neutron dosimeter capable of discerning between thermal and fast neutron doses in real time.

Date: December 31, 2009

Creator: Dunn, William L. & McGregor, Douglas

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Residual radioactivity measurements along the PB target pile

In this brief note, measurements of residual radioactivity made along the PB target pile will be described. This was done as a test of the methods described by P. Gollon (Go76) for predicting such radioactivity based upon surface star density calculations using CASIM. These methods have been extensively used at Fermilab, especially in the design of the Tevatron II target piles. 4 refs., 2 figs.

Date: September 1, 1987

Creator: Cossairt, J.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Temperature dependence of the Westcott g-factor for the actinide nuclides in ENDF/B-VI

Reactor neutron capture and fission reaction rates are determined as the product of the neutron flux density and the neutron capture or fission cross section. The standard energy for tabulation of thermal neutron cross sections is that of room temperature of 20.43{degree}C, corresponding to a neutron energy of 0.0253 eV or a neutron velocity of 2200 m/s. Since most reactors do not operate at a temperature of 20{degree}C, there must be some mechanism for converting the cross section, {sigma}{sub… more

Date: May 1, 1991

Creator: Holden, Norman E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Thermal neutron cross sections for the 1991 table of the isotopes

It has been a decade since the last publication of the Barn Book,'' BNL-325. In preparing a revision to the Table of the Isotopes, a re-evaluation of all of the thermal neutron cross sections has been performed, utilizing the previous data base of the Barn Book'' and all of the more recently published experiments. 5 refs.

Date: May 1, 1991

Creator: Holden, Norman E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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A high intensity positron beam at the Brookhaven reactor

We describe a high intensity, low energy positron beam utilizing high specific activity /sup 64/Cu sources (870 Ci/g) produced in a reactor with high thermal neutron flux. Fast-to-slow moderation can be performed in a self moderation mode or with a transmission moderator. Slow positron rates up to 1.6 x 10/sup 8/ e/sup +//s with a half life of 12.8 h are calculated. Up to 1.0 x 10/sup 8/ e/sup +//s have been observed. New developments including a Ne moderator and an on-line isotope separation p… more

Date: January 1, 1987

Creator: Weber, M.; Lynn, K. G.; Roellig, L. O.; Mills, A. P., Jr. & Moodenbaugh, A. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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ENDF/B-5 fission product cross section evaluations

Cross section evaluations were made for the 196 fission product nuclides on the ENDF/B-5 data files. Most of the evaluations involve updating the capture cross sections of the important absorbers for fast and thermal reactor systems. This included updating thermal values, resonance integrals, resonance parameter sets, and fast capture cross sections. For the fast capture results generalized least-squares calculations were made with the computer code FERRET. Input for these cross section adjustm… more

Date: December 1, 1979

Creator: Schenter, R. E. & England, T. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Capture cross section and gamma-ray spectrum calculations for medium-weight nuclei. [Double-peak, energy-dependent Breit-Wigner model]

A double-peak, energy-dependent Breit-Wigner model of the E1 gamma-ray strength function was applied to nuclei from As to Rh, to predict their neutron capture cross sections and capture gamma-ray spectra. A consistent set of model parameters was obtained in this mass region to describe the step in the low-energy tail of the E1 strength function. This step allows agreement with photonuclear data at high energies, the correct GAMMA/sub gamma/ to be obtained for agreement with neutron capture cros… more

Date: November 14, 1979

Creator: Gardner, M. A. & Gardner, D. G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Comparative studies in direct slow-neutron capture calculations

Primary E1 transitions due to thermal neutron capture by the nuclides /sup 9/Be, /sup 32,34/S, /sup 40,42,44,46,48/Ca, and /sup 58/Ni are quantitatively interpreted by the Lane-Lynn formula and are compared with recent optical model calculations. The two approaches are equivalent provided the internal region of the nucleus is excluded in the optical model approach. Theoretical justifications for such a procedure are briefly presented. 32 refs., 4 tabs.

Date: August 1, 1987

Creator: Mughabghab, S. F.

Item Type: Article

Partner: UNT Libraries Government Documents Department