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Scintillation detector efficiencies for neutrons in the energy region above 20 MeV

Description: The computer program SCINFUL (for SCINtillator FUL1 response) is a program designed to provide a calculated complete pulse-height response anticipated for neutrons being detected by either an NE-213 (liquid) scintillator or an NE-110 (solid) scintillator in the shape of a right circular cylinder. The point neutron source may be placed at any location with respect to the detector, even inside of it. The neutron source may be monoenergetic, or Maxwellian distributed, or distributed between chosen lower and upper bounds. The calculational method uses Monte Carlo techniques, and it is relativistically correct. Extensive comparisons with a variety of experimental data have been made. There is generally overall good agreement (less than 10% differences) of results for SCINFUL calculations with measured integral detector efficiencies for the design incident neutron energy range of 0.1 to 80 MeV. Calculations of differential detector responses, i.e. yield versus response pulse height, are generally within about 5% on the average for incident neutron energies between 16 and 50 MeV and for the upper 70% of the response pulse height. For incident neutron energies between 50 and 80 MeV, the calculated shape of the response agrees with measurements, but the calculations tend to underpredict the absolute values of the measured responses. Extension of the program to compute responses for incident neutron energies greater than 80 MeV will require new experimental data on neutron interactions with carbon. 32 refs., 6 figs., 2 tabs.
Date: January 1, 1991
Creator: Dickens, J.K.
Partner: UNT Libraries Government Documents Department

Tritium monitoring system for near ambient measurements

Description: This paper describes the current status of research on an improved tritium measurement system at the Oak Ridge National Laboratory (ORNL) for the US Navy. Present tritium-in-air monitoring systems installed by the Navy can reliably measure to less than 10 {mu}Ci/m{sup 3}, but medical and safety issues are pushing measurement needs to below 1 {mu}Ci/m{sup 3}, which is equivalent to 1--10 nCi/ml in liquid samples, using calcium metal converter. A significant effort has been expended over the past 10 years by the Navy RADIAC Development Program at ORNL on various schemes to improve the detection of tritium in both air and liquid at near ambient levels. One such scheme includes a liquid flow-through system based on an NE102 sponge scintillator with dual photomultiplier tubes for the tube noise rejection. (This document also contains copies of the slides used for presentation of this paper to the IEEE 1991 Nuclear Science Symposium). 4 refs., 17 figs.
Date: January 1, 1991
Creator: Falter, K.G. & Bauer, M.L.
Partner: UNT Libraries Government Documents Department

Research accomplishments and future goals in particle physics

Description: This document presents our proposal to continue the activities of Boston University researchers in high energy physics research. We have a broad program of participation in both non-accelerator and accelerator-based efforts. High energy research at Boston University has a special focus on the physics program of the Superconducting Supercollider. We are active in research and development for detector subsystems, in the design of experiments, and in study of the phenomenology of the very high energy interactions to be observed at the SSC. The particular areas discussed in this paper are: colliding beams physics; accelerator design physics; MACRO project; proton decay project; theoretical particle physics; muon G-2 project; fast liquid scintillators; SSCINTCAL project; TRD project; massively parallel processing for the SSC; and physics analysis and vertex detector upgrade at L3.
Date: November 30, 1990
Partner: UNT Libraries Government Documents Department

A proposal to search for neutrino oscillations with high sensitivity in the appearance channels. nu. sub. mu. yields. nu. sub e and. nu. sub. mu. yields. nu. sub e

Description: An experiment is proposed to search concurrently for {nu}{sub {mu}} {yields} {nu}{sub e} and {bar {nu}}{sub {mu}} {yields} {bar {nu}{sub e} oscillations with high sensitivity at LAMPF. The detector consists of a tank with 200 tons of dilute liquid scintillator with 850 10-in. photomultiplier tubes mounted on the inside tank covering 28% of the surface. Both Cerenkov light and scintillation light will be detected. The tank will reside inside the existing E645 veto shield and the experiment will make use of the present A6 beam-stop neutrino source. After two years of data collection, 90% confidence level limits on {bar {nu}{sub mu}}({nu}{sub {mu}}) {yields} {bar {nu}}{sub e}({nu}{sub e}) mixing strengths of 2.7(2.7) {times} 10{sup {minus}4} can be obtained for all {Delta}m{sup 2} > 1 eV{sup 2}. Similarly, for maximal mixing the 90% C.L. limits on {Delta}m{sup 2} are 1.7(4.0) {times} 10{sup {minus}2}. This experiment will, therefore, provide the world's best terrestrial limits on {nu}{sub {mu}} {yields} {nu}{sub e}} oscillations. Other physics to be obtained includes measurements of the charged current reactions {nu}{sub e}C {yields} e{sup {minus}}N and {nu}{sub {mu}}C {yields} {mu}{sup {minus}}N, of the inelastic neutral current reaction {nu}C {yields} {nu}C* (15.11- MeV {gamma}), and a search for the rare decays {pi}{sup 0} {yields} {nu}{bar {nu}} and {eta} {yields} {nu}{bar {nu}}.
Date: August 1, 1990
Creator: Lu, X-Q.; Yodh, G. (California Univ., Irvine, CA (USA)); Fung, S.Y.; Kang, J.H.; Shen, B.C.; VanDalen, G.J. (California Univ., Riverside, CA (USA)) et al.
Partner: UNT Libraries Government Documents Department

Neutrino proton scattering and the isosinglet term

Description: Elastic neutrino proton scattering is sensitive to the SU(3) axial isosinglet term which is in turn dependent on the strangeness content of the proton. The uncertainties in the analysis of a neutrino proton elastic scattering experiment are discussed, and an experiment which is insensitive to many of the difficulties of the previous experiment is described.
Date: January 1, 1990
Creator: White, D.H.
Partner: UNT Libraries Government Documents Department

Upper limits on neutron bursts emitted from Ti pressurized D sub 2 gas cells

Description: In a search for bursts of neutrons from Ti in pressurized D{sub 2} gas cells, no statistically significant deviations from the background were observed for events where five or more neutrons are detected over a ten day experiment, including 103 hours of counting with cells on, and 28 hours counting of various backgrounds. Up to four cells were used including some 60 grams of 662-Ti fillings in a pressurized cylinder with 40-60 atmosphere of D{sub 2} gas. Other Ti samples were used too. The samples were cooled to liquid nitrogen temperature and placed in front of the neutron detector while warming up to room temperature. Seven cooling cycles were used, for each sample. The neutron detector system included 12 liquid scintillator neutron detectors, arranged in a close packed geometry, with six detectors in the upper hemisphere and six in the lower hemisphere. A central detector placed 2 cm from the cells was used, in each hemisphere, as a scatterer for a time of flight coincidence measurement, yielding the total coincidence efficiency of {epsilon}=2{plus minus}1%. The system was also used in singles mode to allow for counting with large efficiency. A neutron event is characterized by measuring its pulse heights, pulse shapes, and in some cases its time of flight. Special attention was given to reducing the background by using massive shielding, cosmic ray veto counters and geometrical arrangement that allowed to distinguish between a background event and expected data events. The so obtained background rate is 100 cph in the singles mode'' and in the upper hemisphere 0.4 cph in the coincidence mode.'' We are currently continuing our data analysis in search for random emission and a detailed study of background effects that may reveal the origin of conflicting results reported on neutron emission from cold fusion.'' 3 refs., 5 ...
Date: October 27, 1989
Creator: Rugari, S. L.; France, R. H., III; Gai, M.; Lund, B. J.; Smolen, S. D.; Zhao, Z. et al.
Partner: UNT Libraries Government Documents Department

Studies of nuclei using radioactive beams. [Space Astronomy Lab., Univ. of Florida, Gainesville, Florida]

Description: The 12 month period from May 1988 to July 1989 represents the first full year of our 18 month pilot program in nuclear structure research. In this period, research was initiated to develop a capability for radioactive secondary beams at Argonne National Laboratory using the Atlas and the new Fragment Mass Analyzer (FMA), which is currently under construction. Two major new detector facilities are currently in the final stages of design and testing. The Large-Area, Scintillator Telescope (LAST) detector is fully operational and will be shipped to Argonne National Laboratory in August for fit-tests and in-beam calibrations. The first segments of a new sixteen-segment neutron multiplicity detector have been built and tested. The remaining segments are currently being constructed. Research was continued in the areas of (1) Coulomb excitation studies of rare earth and actinide nuclei; (2) In-beam, gamma-ray spectroscopy of nuclei in the mass 100 region, and (3) Advanced detector design. Several journal articles and abstracts were published or submitted for publication in the reporting period, and others are currently in preparation. Three graduate students participated in the program, one from the University of Florida and two from the Royal Institute of Technology, Stockholm, Sweden.
Date: July 1, 1989
Creator: Piercey, R .B.
Partner: UNT Libraries Government Documents Department

Detectors for the Superconducting Super Collider, design concepts, and simulation

Description: The physics of compensation calorimetry is reviewed in the light of the need of the Superconducting Super Collider (SSC) detectors. The four major detector types: liquid argon, scintillator, room temperature liquids, and silicon, are analyzed with respect to some of their strengths and weaknesses. Finally, general comments are presented which reflect the reliability of simulation code systems. 29 refs., 20 figs., 6 tabs.
Date: January 1, 1989
Creator: Gabriel, T.A.
Partner: UNT Libraries Government Documents Department

Development of neutron multiplicity counters for safeguards assay

Description: This paper reports on the development of a new generation of neutron multiplicity counters for assaying impure plutonium. The new counters will be able to obtain three measured parameters from the neutron multiplicity distribution and will be able to determine sample mass, multiplication, and (..cap alpha..,n) reaction rate, making it possible to obtain a more matrix-independent assay of moist or impure materials. This paper describes the existing prototype multiplicity counters and evaluates their performance using assay variance as a figure of merit. The best performance to date is obtained with a high-efficiency, low die-away-time thermal neutron counter with shift-register electronics. 10 refs., 2 figs., 4 tabs.
Date: January 1, 1989
Creator: Ensslin, N.
Partner: UNT Libraries Government Documents Department

Multi-energy neutron detector for counting thermal neutrons, high-energy neutrons, and gamma photons separately

Description: This scintillation detector is composed of two scintillators optically coupled and mounted on a single photomultiplier tube. The first scintillator is a {sup 6}Li-loaded glass that has high efficiency for thermal neutrons, and the second is a liquid scintillator (BC 501) that has fairly high efficiency for higher energy neutrons. The {sup 6}Li glass scintillator emits light with a characteristic time constant of {approximately}60 ns, whereas light emitted in the liquid scintillator by proton recoil from energetic neutrons has a time constant of {approximately}30 ns and the time constant for scintillations occurring from gamma-scattered Compton electrons in the liquid scintillator is {approximately}3.7 ns. These differences in light decay time constants make this detector conducive to electronic separation of pulses generated by the three different radiations. Thermal neutrons, high-energy neutrons, a gamma radiation can be counted separately by operating this detector with a pulse-shape discriminator recently developed. Experimental data demonstrates the proof of principle of this dual scintillator detector for many applications. 4 figs.
Date: January 1, 1989
Creator: Chiles, M.M.; Bauer, M.L. & McElhaney, S.A.
Partner: UNT Libraries Government Documents Department

Multi-energy neutron detector for counting thermal neutrons, high-energy neutrons, and gamma photons separately

Description: The need for an improved, compact, wide-energy neutron detector for neutron monitoring and surveillance in nuclear facilities and weapons storage, where a possibility of fission excursion exists, led to development of a single detector that is sensitive to thermal neutrons, high-energy neutrons, and gamma radiation. Previously, separate detectors have been required to count these three different radiations separately. This development is a great advantage when experimental space is limited. 4 figs.
Date: January 1, 1989
Creator: Chiles, M.M. & McElhaney, S.A.
Partner: UNT Libraries Government Documents Department

The neutrino program at LAMPF

Description: There are two neutrino experiments that this paper discusses: the first experiment is designed to verify the interference between charged and neutral current amplitudes in {nu}{sub e}- e scattering. The experiment is situated at 90{degree} to the beam stop, and detected recoil electrons from neutrino electron scattering. The experiment is sensitive to recoil electrons from {nu}{sub {mu}}, {nu}{sub e}, {bar {nu}}{sub {mu}} but the cross section for {nu}{sub e} - e scattering is the dominant contribution. The magnitude of this cross section depends on the size of the interference term between charged and neutral current scattering, and the value for this term is {minus}1.07 {plus minus} 0.017 {plus minus} 0.11 to be compared to {minus}1.08 from standard electroweak theory with sin{sup 2}{theta}{sub W} = 0.23. The observation of this interference is unique to this experiment. The second experiment, which is presently finishing data analysis after concluding data taking in 1989, is a search for neutrino oscillations of the type {bar {nu}}{sub mu} {yields} {bar {nu}}{sub e}. The experiment was designed to search for the reaction {bar {nu}}{sub e} + p {yields} e{sup +} + n, which has a large relative cross section compared to that on complex nuclei due to the absence of Pauli Suppression of the reaction on free nucleons producing electrons in the energy range 30--50 MeV in contrast to the dominant background from {nu}{sub e} + {sup 12}C {yields} e{sup +} + {sup 12}N, in which the electron energies are limited to 30 MeV from the Q value of the reaction. 5 refs., 13 figs.
Date: January 1, 1989
Creator: White, D.H.
Partner: UNT Libraries Government Documents Department

Use of liquid scintillation in the appraisal of non-radioactive waste shipments from nuclear facilities

Description: On the Savannah River Site (SRS), non-radioactive or clean waste, is normally assayed to appraise the extent of surface contamination by using a survey meter. Because of the nature of the operations conducted at SRS, the majority of the waste generated is treated as contaminated waste until proven otherwise. Before such waste can be shipped off-site, more rigorous assay must demonstrate compliance with government standards. In particular, it is necessary to appraise the samples with regard to the Department of Transportation (DOT) guideline for a total activity of 2 nanoCuries per gram of waste material. Furthermore, the assay methods must be sufficient to comply with Environmental Protection Agency (EPA) regulations to prevent overcrowding of waste storage locations. Thus, the present work developed efficient liquid scintillation methods for meeting these requirements. The method of phase separation, sample processing, and liquid scintillation analysis proved effective for the analysis of mixed phase, hydrocarbon based waste samples. The described method was readily applicable to a variety of circumstances and was straightforward enough to be used by staff analysts after a minimum of training. The results were obtained in far shorter time (usually less than 2 hours for a single sample) than would be required for other typical methods of analysis. All samples analyzed by the methods presented were found to have activities below the 2 nCi/g DOT guideline for shipment of non-nuclear waste. 5 refs., 3 figs., 1 tab.
Date: January 1, 1989
Creator: McDowell, W.L.
Partner: UNT Libraries Government Documents Department

Gamma ray emission from spheres pulsed with D-T neutrons: Results of May 1987 experiments at RTNS-1

Description: Subsequent to the analysis of the June 1986 series of experiments at RTNS-1, we thought it sensible to repeat some of the experiments with greater care given to the high energy portions of the effluent gamma ray spectra. In addition, some new materials were recommended for study, such as silicon. And since among our earlier experiments we observed data which was not highly reproducible, repeated runs would provide a quantitative assessment of the precision of the experiments. Accordingly, we followed the procedure outlined in UCID-20884. First, we calibrated the NE-213 detector with standard gamma ray sources and checked for linearity of pulse height with energy deposited by electrons. We then conducted experiments at RTNS-1, using spherical configurations of C, Si, Al, H/sub 2/O, N/sub 2/,Ti, Fe, and C/sub 2/F/sub 4/. The H/sub 2/O was contained in a modified glass flask, while the liquid nitrogen was held in a double-walled steel dewar. 25 refs., 17 figs., 9 tabs.
Date: November 1, 1987
Creator: Goldberg, E.; Hansen, L.F.; Howerton, R.J.; Komoto, T.T. & Pohl, B.A.
Partner: UNT Libraries Government Documents Department

Energy spectra of the pneumatically positioned neutron sources at LLNL's Hazards control standards and calibration facility

Description: The Hazards Control Department of Lawrence Livermore National Laboratory maintains a Standards and Calibration Laboratory that includes three neutron sources (two /sup 252/Cf and one /sup 238/PuBe that can be positioned pneumatically for irradiations. Ten moderators exist to modify the neutron energy spectra produced by these sources. The thicknesses and materials of these moderators are: 25-cm water; 5-, 10-, 15-, and 25-cm heavy water; 20-cm aluminum; and 2-, 5-, 10-, and 15-cm polyethylene. We used a multisphere spectrometer to measure the neutron spectra at 2 m from both the PuBe source and the smaller Cf source, with the sources bare, and in all of the moderators. These data were reduced in 25 energy groups ranging from 0.25 eV to 16 MeV. Except for the 15-m polyethylene moderator, we also made measurements using a liquid-scintillator fast-neutron spectrometer. These data were reduced in 0.1-MeV increments from 0.5 to 12.5 MeV. Spectra from the measurements and from independent calculations are presented in tabular and graphic form. Dosimetric values, calculated from both the measured and calculated spectra, are also presented.
Date: June 15, 1987
Creator: Thorngate, J.H.
Partner: UNT Libraries Government Documents Department

Measurement of long-lived isotopes in fusion materials

Description: Neutron cross section measurements are reviewed for the production of long-lived isotopes in fusion reactor materials. Samples were irradiated at 14.5 to 14.8 MeV at the RTNSII facility. Long-lived reaction products were detected using gamma and x-ray spectroscopy, liquid scintillation spectrometry, and accelerator mass spectrometry. Radiochemical separations were performed for many samples prior to analysis. Results are summarized for reactions leading to /sup 26/Al (720,000 y), /sup 53/Mn (3,700,000 y), /sup 55/Fe (2.73 y), /sup 63/Ni (100 y), /sup 59/Ni (76,000 y), /sup 91/Nb (700 y), and /sup 94/Nb (20,300 y). 17 refs., 2 figs., 4 tabs.
Date: January 1, 1987
Creator: Greenwood, L.R. & Bowers, D.L.
Partner: UNT Libraries Government Documents Department

Search for neutrino oscillations at the Brookhaven AGS

Description: We report on a search for neutrino oscillations of the type nu/sub ..mu../ ..-->.. nu/sub e/ in a detector located an effective distance of 96m from the neutrino source in the wide band neutrino beam at the Brookhaven AGS. No excess of electron events was observed. The resulting upper limit on the strength of the mixing between nu/sub ..mu../ and nu/sub e/ in the case of large mass difference ..delta..m/sup 2/ = absolute value m/sub 1//sup 2/ - m/sub 2//sup 2/ between the neutrino mass eigenstates m/sub 1/ and m/sub 2/ is sin/sup 2/2..cap alpha.. less than or equal to 3.4 x 10/sup -3/ at 90% CL. The corresponding upper limit for small mass difference is ..delta..m/sup 2/sin2..cap alpha.. < 0.43 eV/sup 2/. 9 refs.
Date: February 20, 1985
Creator: Ahrens, L.A.; Aronson, S.H.; Connolly, P.L.; Gibbard, B.G.; Murtagh, M.J.; Murtagh, S.J. et al.
Partner: UNT Libraries Government Documents Department

Measurement of tritium permeation through resistant materials near room temperature

Description: To measure tritium permeation through low-permeability materials at 50 to 170/sup 0/C, we use highly-sensitive liquid scintillation counting to detect the permeating tritium. To validate our method, we conducted extensive experiments with copper, for which much data exists for comparison. We report permeability of tritium through copper at 50, 100, and 170/sup 0/C, and discuss details of the experimental technique. Further plans are outlined. 15 refs., 5 figs., 1 tab.
Date: January 1, 1985
Creator: Maienschein, J.; DuVal, V.; McMurphy, F.; Uribe, F.; Musket, R. & Brown, D.
Partner: UNT Libraries Government Documents Department

Neutron spectra as a function of angle at two meters from the Little Boy assembly

Description: Measurements of neutron spectra produced by the Los Alamos National Laboratory (LANL) Little Boy replica assembly (Comet) were made with a combined multisphere and liquid scintillator system, that has been widely used at the Lawrence Livermore National Laboratory. The combined system was used for measurements at the side (90/sup 0/) and nose (0/sup 0/) of the assembly; additional measurements were made at 45/sup 0/ using only the liquid scintillator. Data were obtained at two meters from the center of the reactive region of the assembly, with good agreement between the multisphere and scintillator results. Comparison with liquid scintillator measurements performed by experimenters from the Canadian Defence Research Establishment, Ottawa (DREO) and calculations from LANL depended on the specific angle, obtaining the best agreement at 90/sup 0/. 32 references, 11 figures, 4 tables.
Date: July 2, 1984
Creator: Griffith, R.V.; Huntzinger, C.J. & Thorngate, J.H.
Partner: UNT Libraries Government Documents Department

nu/sub. mu. /C/sup 12/. -->. mu. /sup -/X cross section and nu/sub. mu. / - nu/sub e/ oscillation using the decay-in-flight source at Line-E of LAMPF

Description: This paper describes an experiment to measure the nu/sub ..mu../C/sup 12/ ..-->.. ..mu../sup -/X cross section and to detect nu/sub ..mu../ - nu/sub e/ oscillations. A test run was completed last year. The detector has been calibrated and backgrounds are under study. The sensitivity of the experiment is estimated for the 1985 LAMPF run cycle to be +-20% for the cross section measurement and the 90% confidence level limits for the neutrino oscillation experiment are sin/sup 2/2THETA < 10/sup -3/ and ..delta..m/sup 2/ < 10/sup -1/ eV/sup 2/.
Date: January 1, 1984
Creator: Clearwater, S.
Partner: UNT Libraries Government Documents Department

Monopole search using an accelerator detector

Description: A neutrino detector at the Brookhaven AGS has been used to investigate the feasibility of using an already constructed apparatus for GUT monopole searches. A flux limit (90%CL) of 5.2 x 10/sup -12/ cm/sup -2/ sec/sup -1/ str/sup -1/ was found. The limitations of such an approach are discussed.
Date: December 20, 1983
Creator: Ahrenes, L.A.; Aronson, S.H.; Connolly, P.L.; Erickson, T.E.; Gibbard, B.G.; Montag, M. et al.
Partner: UNT Libraries Government Documents Department

Data acquisition for a large neutrino detector

Description: A hierarchical, distributed intelligence data acquisition system which has been used for the past two years in neutrino experiments at Brookhaven National Laboratory is described. Performance characteristics and the nature of problems encountered in bringing the system to maturity are discussed and some generalizations of the experience are suggested.
Date: January 1, 1983
Creator: Ahrens, L.A.; Aronson, S.A. & Connolly, P.L.
Partner: UNT Libraries Government Documents Department

Liquid-scintillation alpha-detection techniques

Description: Accurate, quantitative determinations of alpha-emitting nuclides by conventional plate-counting methods are difficult because of sample self-absorption problems in counting and because of non-reproducible losses in conventional sample separation methods. Liquid scintillation alpha spectrometry offers an attractive with no sample self-absorption or geometry problems and with 100% counting efficiency. Sample preparation may include extraction of the alpha emitter of interest by a specific organic-phase-soluble compound directly into the liquid scintillation counting medium. Detection electronics use energy and pulse-shape discrimination to yield alpha spectra without beta and gamma background interference. Specific procedures have been developed for gross alpha, uranium, plutonium, thorium, and polonium assay. Possibilities for a large number of other applications exist. Accuracy and reproducibility are typically in the 1% range. Backgrounds on the order of 0.01 cpm are readily achievable. The paper will present an overview of liquid scintillation alpha counting techniques and some of the results achieved for specific applications.
Date: January 1, 1983
Creator: McKlveen, J.W. & McDowell, W.J.
Partner: UNT Libraries Government Documents Department

Monitoring tritium in air containing other radioactive gases

Description: A brief survey is presented of methods that have been developed for active tritium monitoring that may be applied to measure tritium concentrations in air containing /sup 13/N, /sup 16/N, and /sup 41/Ar produced by D-T neutrons. Included are instruments that employ current subtraction to achieve discriminations and others that selectively remove atmospheric water vapor from stream of activated air.
Date: September 1, 1982
Creator: Jalbert, R.A.
Partner: UNT Libraries Government Documents Department