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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

Homestake tracking spectrometer: a one-mile deep 1400-ton liquid-scintillation nucleon-decay detector

Description: We describe a proposed nucleon decay detector able to demonstrate the existence of nucleon decay for lifetimes up to 5 x 10/sup 32/ yr. The proposed instrument is a self-vetoed completely-active 1400-ton liquid scintillation Tracking Spectrometer to be located in the Homestake Mine at a depth of 4200 mwe, where the cosmic ray muon flux is only 1100/m/sup 2//yr, more than 10/sup 7/ times lower than the flux at the earth's surface. Based on computer simulations and laboratory measurements, the Tracking Spectrometer will have a spatial resolution of +- 15 cm (0.32 radiation lengths); energy resolution of +- 4.2%; and time resolution of +-1.3 ns. Because liquid scintillator responds to total ionization energy, all neutrinoless nucleon decay modes will produce a sharp (+- 4.2%) total energy peak at approximately 938 MeV, thereby allowing clear separation of nucleon decay events from atmospheric neutrino and other backgrounds. The instrument will be about equally sensitive to most nucleon decay modes. It will be able to identify most of the likely decay modes (including n ..-->.. ..nu.. + K/sub s//sup 0/ as suggested by supersymmetric grand unified theories), as well as determine the charge of lepton secondaries and the polarization of secondary muons.
Date: January 1, 1982
Creator: Cherry, M.L.; Davidson, I.; Lande, K.; Lee, C.K.; Marshall, E.; Steinberg, R.I. et al.
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

Alpha liquid scintillation counting: past, present, and future

Description: Beta liquid scintillation counting has been used for about 30 years, and its effectiveness for alpha particles has been known for almost that long; however, the technique has not been widely applied to alpha particle detection because of poor energy resolution, high background, and variable interference from beta and gamma radiation. Beginning with the work of Horrocks in the early 1960s, improvements in energy resolution and background rejection have been made. Further developments at Oak Ridge National Laboratory over the past 10 to 12 years have resulted in improved methods of sample preparation (using liquid-liquid extraction methods to isolate the sample and introduce it into the scintillator) and better instrumentation, including electronic rejection of beta and gamma pulses. Energy resolutions of 200- to 300-keV FWHM and background counts of 0.01 cpm are now routine. Alpha liquid scintillation spectrometry is now suitable for a wide range of applications, from the accurate quantitative determination of relatively large amounts of known nuclides in laboratory-generated samples to the detection and identification of very small, subpicocurie amounts of alpha emitters in environmental-type samples. Suitable nuclide separation procedures, sample preparation methods, and instrument configurations are outlined for a variety of analyses.
Date: January 1, 1979
Creator: McDowell, W.J.
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

Proposal to assemble a high resolution-electron sensitive-energy flow calorimeter in the NEULAND spectrometer

Description: A ..gamma.. catcher and a liquid scintillation calorimeter module in a simple configuration that is well suited to the investigation of several different neutrino induced processes are described. The variety of neutrino beams now available at Fermilab and synchrotron intensity and energy together with the high resolution calorimeter allow a multiplicity of experiments to be carried out with a single detector configuration.
Date: January 1, 1977
Partner: UNT Libraries Government Documents Department

Comparison of calculated and experimental neutron attenuation and streaming data for fusion reactor design

Description: Integral experiments that measure the neutron and gamma-ray energy spectra resulting from the attenuation of approx. 14 MeV T(D,n)/sup 4/He reaction neutrons in laminated slabs of stainless steel type 304, borated polyethylene, and a tungsten alloy (Hevimet) and from neutrons streaming through a 30-cm-diameter iron duct (L/D = 3) imbedded in a concrete shield have been performed at the Oak Ridge National Laboratory. The facility, NE-213 liquid scintillator detector system, and experimental techniques used to obtain the measured data are described. The two-dimensional discrete ordinates radiation transport codes, calculational models, and nuclear data used in the analysis of the experiments are reviewed.
Date: January 1, 1980
Creator: Santoro, R.T.; Alsmiller, R.G. Jr.; Barnes, J.M. & Chapman, G.T.
Partner: UNT Libraries Government Documents Department

Long wavelength scintillators for fiber-optic applications

Description: The use of fiber optics in plasma diagnostics has spurred the development of long wavelength scintillators with fast temporal characteristics. In this paper we describe several new liquid scintillator systems with fluorescent emissions maxima up to 730 nm. Subnanosecond scintillator FWHM response times have been obtained by the operation of liquid scintillators at elevated temperatures. Data on fiber system sensitivity versus fiber length and scintillator emission wavelength will be presented.
Date: January 1, 1980
Creator: Lyons, P.B.; Franks, L.; Lutz, S.; Flournoy, J. & Fullman, E.
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