94 Matching Results

Search Results

Advanced search parameters have been applied.

Measurement of actinides in environmental samples by Photo-Electron Rejecting Alpha Liquid Scintillation

Description: This work describes the adaptation of extractive scintillation with a Photo-Electron Rejecting Alpha Liquid Scintillation (PERALS) (ORDELA, Inc.) spectrometer to the analysis of actinides in environmental samples from the Savannah River Site (SRS). Environmental quality assurance standards and actual water samples were treated by one of two methods; either a two step direct extraction, or for more complex samples, pretreatment by an extraction chromatographic separation prior to measurement of the alpha activity by PERALS.
Date: May 1, 1994
Creator: Cadieux, J. R.; Clark, S.; Fjeld, R. A.; Reboul, S. & Sowder, A.
Partner: UNT Libraries Government Documents Department

Preliminary detector design ST862-prototype neutron detector

Description: The detection of fast neutrons has been accomplished with commercially available liquid scintillators in detectors. Liquid scintillators discriminate fast neutrons from gamma radiation by discarding pulses with short decay constants. However, pulse-timing methods require expensive, bulky equipment and a high degree of technical sophistication in the user. Researchers at Pacific Northwest Laboratory have developed a new class of scintillating material, polymerizing crystals of CaF{sub 2}(Eu) and liquid acrylate monomers with matched indexes of refraction. The new detectors avoid the pulse-timing methods of liquid detectors and allow detectors to be large and relatively light. Fast neutrons can be discriminated from gamma radiation solely on the basis of pulse height (i.e., energy deposition). Using these detectors, a hand-held neutron detection instrument is proposed that can operate on battery power for 8 to 12 hours and be easily used in field conditions for surveying vehicles and structures.
Date: December 1, 1993
Creator: Miller, S. D.; Affinito, J. D. & Sisk, D. R.
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

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

Human radiation studies: Remembering the early years: Oral history of cell biologist Don Francis Petersen, Ph.D., conducted November 29, 1994

Description: This report is a transcript of an interview of Dr. Don Francis Petersen by representatives of the US DOE Office of Human Radiation Experiments. Dr. Petersen was selected for this interview because of his long research career at Los Alamos and his knowledge of the Atomic Energy Commission`s biomedical program. Dr. Petersen did not personally conduct research on human subjects. After a brief biographical sketch Dr. Petersen discusses his remembrances of the early use of radionuclides as biological tracers, aspects of nuclear weapons testing in the 1940`s and 1950`s including fallout studies, the means by which research projects were approved, use of humans in the whole-body counter, and the Health Division Biomedical responsibilities.
Date: August 1, 1995
Partner: UNT Libraries Government Documents Department

A proposal for the continuation of support for the Intercampus Institute for Research at Particle Accelerators: April 1, 1994--March 31, 1995

Description: This report gives a brief summary of IIRPA activities for the past year which include: the Liquid Scintillator Neutrino Detector (LSND) experiment at LANL, both hardware and software efforts; B Factory design efforts; B Factory detector development efforts; TPC/Two-Gamma roundup; and other activities and new initiatives. Also given is next year`s plan for these activities.
Date: December 31, 1995
Partner: UNT Libraries Government Documents Department

Liquid scintillators for optical-fiber applications

Description: A multicomponent liquid scintillator solution for use as a radiation-to-light converter in conjunction with a fiber optic transmission system. The scintillator includes a quantity of 1, 2, 4, 5, 3H, 6H, 1 OH, tetrahydro-8-trifluoromethyl (1) benzopyrano (9, 9a, 1-gh) quinolizin-10-one (Coumarin) as a solute in a fluor solvent such as benzyl alcohol or pseudo-cumene. The use of BIBUQ as an additional or primary solute is also disclosed.
Date: June 1, 1981
Creator: Franks, L.A. & Lutz, S.S.
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

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

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

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

New advanced in alpha spectrometry by liquid scintillation methods

Description: Although the ability to count alpha particles by liquid scintillation methods has been long recognized, limited use has been made of the method because of problems of high background and alpha energy identification. In recent years some new developments in methods of introducing the alpha-emitting nuclide to the scintillator, in detector construction, and in electronics for processing the energy analog and time analog signals from the detector have allowed significant alleviation of the problems of alpha spectrometry by liquid scintillation. Energy resolutions of 200 to 300 keV full peak width at half maximum and background counts of < 0.01 counts/min with rejection with rejection of > 99% of all beta plus gamma interference is now possible. 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 available for a variety of analyses.
Date: January 1, 1979
Creator: McDowell, W.J. & Case, G.N.
Partner: UNT Libraries Government Documents Department

Planning for the next generation of proton-decay experiments in the United States

Description: There are now three well-developed proposals for new proton decay detectors to be built in the United States. These are the 1000 to 5000-ton Soudan 2 tracking calorimeter, the 1400-ton Homestake II liquid scintillator Tracking Spectrometer, and the 2500-ton University of Pennsylvania liquid-scintillator - proportional-drift-cell calorimeter. These proposals were reviewed by the Department of Energy Technical Assessment Panel on Proton Decay in February 1982. I shall describe the Soudan and Pennsylvania proposals, present the latest results from the 31-ton Soudan 1 experiment, and discuss the recommendations of the DOE Panel. Following these recommendations, a one-week workshop, to be held at Argonne in June, will focus on the optimization of techniques for future experiments.
Date: January 1, 1982
Creator: Ayres, D.S.
Partner: UNT Libraries Government Documents Department

Ternary liquid scintillator for optical-fiber applications

Description: A multicomponent liquid scintillator solution for use as a radiation-to-light converter in conjunction with a fiber optic transmission system. The scintillator includes a quantity of 5-amino-9-diethylaminobenz (a) phenoxazonium nitrate (Nile Blue Nitrate) as a solute in a fluor solvent such as benzyl alcohol. The use of PPD as an additional solute is also disclosed. The system is controllable by addition of a suitable quenching agent, such as phenol.
Date: June 1, 1981
Creator: Franks, L.A. & Lutz, S.S.
Partner: UNT Libraries Government Documents Department

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

Design optimization of liquid scintillator cosmic-ray veto detector with BBQ shifter

Description: Certain design characteristics of a liquid scintillator detector for charged cosmic particles, have been studied. These include evaluation of scintillator emission spectra, absorption in various thicknesses of BBQ shifter bars and effective transmission in long lengths of BBQ acrylic. For our BBQ sample, 12.5 mm thick with semicircular shape, the shifted light was transmitted with 2.0 m absorption length.
Date: October 1, 1981
Creator: Kruse, H.W.; Egdorf, S.S. & Simmons, D.F.
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

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