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Radiation-induced mesotheliomas in rats

Description: Mesotheliomas have been reported in rats that inhaled plutonium, but these tumors have not been extensively studied. To investigate a possible role for inhaled radionuclides in the induction of mesotheliomas, four life-span studies conducted at the Inhalation Toxicology Research Institute are reviewed. A total of 3076 F344 rats were exposed by inhalation to aerosols of {sup 239}PuO{sub 2}, mixed uranium-plutonium oxide, or {sup 144}CeO{sub 2}. Results showed that a low incidence of pleural mesotheliomas was induced by either alpha- or beta-emitting radionuclides deposited and retained in the lung. Chronic alpha irradiation was more effective per unit dose in producing mesotheliomas than chronic beta irradiation of the lung by a factor of 15. 7 refs., 1 tab., 7 figs. (MHB)
Date: January 1, 1990
Creator: Hahn, F.F.; Haley, P.J.; Hubbs, A.F.; Hoover, M.D. & Lundgren, D.L.
Partner: UNT Libraries Government Documents Department

The double beta decay spectrum of sup 100 Mo as measured with a TPC (time projection chamber)

Description: A time projection chamber with 8.3 grams of enriched {sup 100}MoO{sub 3} as the central electrode has been operating approximately five months in an underground laboratory. A preliminary analysis of the two-electron sum energy spectrum, the spectrum of those same electrons taken singly, and the opening angle distribution yields a half life of 1.16{sub -0.08}{sup +0.34} {times} 10{sup 19} y at the 68% confidence level for two-neutrino double beta decay of {sup 100}Mo. 9 refs., 8 figs.
Date: January 1, 1990
Creator: Elliott, S.R. (Los Alamos National Lab., NM (USA)); Moe, M.K.; Nelson, M.A. & Vient, M.A. (California Univ., Irvine, CA (USA))
Partner: UNT Libraries Government Documents Department

In-vivo measurements of Pb-210 to determine cumulative exposure to radon daughters: A pilot study

Description: The feasibility of measuring Pb-210 in vivo in the skulls of those individuals who have resided in homes with above average levels of radon/radon daughters, has now been successfully demonstrated. These values, when incorporated into metabolic models of Pb-210 in the body including other related physical parameters, can be used for the calculation of a realistic estimate of a resident's cumulative exposure to radon and its' decay products. Data are presented for 26 subjects exposed to higher than average concentrations of radon i.e. ranging from 10 to 120 pCi/l, for various periods of time. Their skeletal Pb-210 burdens are compared to measurement results of a population of individuals presumed to have been exposed to values which are more representative of average levels i.e. <1pCi/1. Results of a study to determine the biological retention of Pb-210 in the human skeleton for use in the metabolic model relating skull burdens of this nuclide to cumulative radon/daughter exposure, are also described. At the present time, our measurements, made over a period of 10 years, of an individual with a significant Pb-210 burden, indicate a biological half-time of approximately 57 years and an effective half-life of 16 years. 4 refs., 11 figs.
Date: October 1, 1990
Creator: Laurer, G.R.; Cohen, N. (New York Univ., Tuxedo, NY (USA). Inst. of Environmental Medicine); Stark, A. & Ju, C. (New York State Dept. of Health, Albany, NY (USA). Bureau of Environmental and Occupational Epidemiology)
Partner: UNT Libraries Government Documents Department

Spectroscopic studies near the proton drip line

Description: We have investigated nuclei close to the proton drip line by using heavy-ion fusion reactions to produce extremely neutron-deficient nuclides. Their nuclear decay properties were studied by using on-line isotope separators at Oak Ridge (UNISOR) and Berkeley (OASIS), the Oak Ridge National Laboratory velocity filter, and a fast helium-gas-jet transport system at Lawrence Berkeley Laboratory 88-Inch Cyclotron. Many isotopes, isomers, and {beta}-delayed-proton and {alpha}-particle emitters were discovered. This contribution summarizes three topics that are part of our overall program: decay rates of even-even {alpha}-particle emitters, mass excesses of {sup 181}Pb, {sup 182}Pb, and {sup 183}Pb, and {beta}-delayed proton emitters near N = 82. 14 refs., 6 figs.
Date: January 1, 1990
Creator: Toth, K.S. (Oak Ridge National Lab., TN (USA)); Moltz, D.M.; Nitschke, J.M.; Wilmarth, P.A. (Lawrence Berkeley Lab., CA (USA)) & Robertson, J.D. (Kentucky Univ., Lexington, KY (USA))
Partner: UNT Libraries Government Documents Department

Test of pre-ENDF/B-VI decay data and fission yields

Description: Pre-ENDF/B-VI nuclear decay data and fission yields have been supplemented by average beta and gamma energies and Pn-values from recent experiments at Studsvik. This data base has been used for a series of summation calculations, and the results have been compared with experimental determinations of decay heat and of delayed-neutron effects. The comparisons are limited to thermal fission of {sup 235}U and {sup 239}Pu and to fast fission of {sup 238}U. The general impression of the comparisons is that the data base does reproduce experimental results satisfactorily (with a few exceptions) within the combined limits of error of the experimental determinations and the calculation. 21 refs., 15 figs.
Date: October 1, 1990
Creator: Rudstam, G. & England, T.R.
Partner: UNT Libraries Government Documents Department

Double beta decay of U-238

Description: During the last period, two samples of 33 yr old uranyl nitrate have been examined for the accumulation of Pu-238 formed as a result of double beta decay. The 2.5 kg sample has led only to an upper limit of 6 {times} 10{sup 20} yr. The 8.5 kg sample has produced positive results corresponding to a half-life of 2 {times} 10{sup 21 } yr. The possibility of contaminating nuclear reactions has been carefully examined and eliminated. The possibility that contamination may have been introduced by the large quantities of chemicals that were used is being investigated. 5 refs.
Date: November 1, 1990
Creator: Turkevich, A. & Economou, T.
Partner: UNT Libraries Government Documents Department

Characteristics of the samples in the FNG fission deposit collection

Description: Information concerning the samples in the Fast Neutron Generator (FNG) Group's fission deposit collection has been assembled. This includes the physical dimensions, isotopic analyses, half-lives, alpha emission rates specific activities and deposit weights. 10 refs., 9 figs., 5 tabs.
Date: December 1, 1990
Creator: Meadows, J.W.
Partner: UNT Libraries Government Documents Department

sup 176 Lu: An unreliable s-process chronometer

Description: A level scheme of {sup 176}Lu up to {approximately}1400 keV excitation energy is deduced from a gamma-gamma coincidence experiment and previously published particle transfer data. 170 gamma-ray transitions are placed between 85 levels, confirming many of the previously established levels and some of the decay scheme. A level at 835.5 keV (J{sup {pi}} = 5{sup {minus}}, t{sub 1/2} < 10 ns) decays with substantial strength to both the ground state (7{sup {minus}}, 4.08 {times} 10{sup 10} yr) and the 122.9 keV isomer (1{sup {minus}}, 3.7 hr). The presence of this level guarantees the thermal equilibration of {sup 176}Lu{sup g,m} for temperatures greater than 3 {times} 10{sup 8} K and therefore during s-process nucleosynthesis. The resulting extreme temperature sensitivity of its effective half-life rules out the use of {sup 176}Lu as an s-process chronometer. The use of {sup 176}Lu to determine s-process temperatures is discussed. 30 refs., 11 figs., 3 tabs.
Date: November 1, 1990
Creator: Lesko, K.T.; Norman, E.B.; Larimer, R.M. & Sur, B.
Partner: UNT Libraries Government Documents Department

An evaluation of the Nb-93(n,n prime )Nb-93m dosimeter reaction for ENDF/B-VI

Description: The Nb-93(n,n{prime})Nb-93m reaction plays an important role in nuclear energy applications. Because of its low threshold energy and relatively long half-life, it is a desirable reaction for long-term neutron fluence dosimetry in nuclear fission reactors. An evaluation of the differential cross section for this reaction was completed in 1985 by this laboratory as part of a comprehensive effort involving all neutron cross sections for niobium. The objective was to provide input for ENDF/B-VI. It was difficult to produce a reliable evaluation for this reaction in 1985 because the information available then was sparse and quite uncertain. In fact, that evaluation was based entirely on nuclear model calculations. The evaluated cross sections below 0.7 MeV were derived from calculations carried out in this laboratory, while the higher energy values were obtained from the work of Strohmaier and co-workers. In 1985 there was only one published experimental differential cross section value to consider for this reaction. Even the half-life of Nb-93m was in serious doubt. During the five years between the completion of the earlier evaluation and the finalization of ENDF/B-VI there have been some significant improvements and additions to the experimental database for this reaction. Also, new model calculations have been performed. Therefore, it was considered worthwhile to produce a new evaluation of Nb-93(n,n{prime})Nb-93m for ENDF/B-VI which would supplant the one that had been completed in 1985.
Date: November 1, 1990
Creator: Smith, D.L. & Geraldo, L.P.
Partner: UNT Libraries Government Documents Department

Safety and environmental aspects of HYLIFE-II

Description: The HYLIFE-II inertial confinement fusion reactor uses a Flibe spray for blast chamber protection and tritium breeding. HYLIFE-II is passively safe, having no large sources of energy available to disperse radioactive materials. The dominant activation product is {sup 18}F (half-life 110 minutes). Only a small fraction (< 10{sup {minus}5}) of the Flibe activation products would be mobilized. The offsite dose from a severe accident involving simultaneous failure of the blast chamber and containment building would be < 0.2 mSv (20 mrem), and N-stamp requirements could be avoided in the blast chamber and coolant systems. The required tritium removal efficiencies are quantified. 10 refs., 1 fig.
Date: January 1, 1990
Creator: Dolan, T.J. & Longhurst, G.R. (Idaho National Engineering Lab., Idaho Falls, ID (USA))
Partner: UNT Libraries Government Documents Department

An interesting finding in sup 229 Th

Description: Work at INEL has recently established that the first excited states of {sup 229}Th forms a closely spaced doublet with the ground state, the separation being 1 {plus minus} 4 electron volts. A discussion of the data and the reasoning supporting this unprecedented finding is given. Some potential applications are briefly mentioned. 27 refs., 3 figs., 2 tabs.
Date: January 1, 1990
Creator: Reich, C.W.
Partner: UNT Libraries Government Documents Department

The synthetic elements

Description: Prior to 1940, the heaviest element known was uranium, discovered in 1789. Since that time the elements 93 through 109 have been synthesized and identified and the elements 43, 61, 85, and 87 which were missing form the periodic tables of the 1930's have been discovered. The techniques and problems involved in these discoveries and the placement of the transuranium elements in the periodic table will be discussed. The production and positive identification of elements heavier than Md (Z=101), which have very short half-lives and can only be produced an atom-at-a-time, are very difficult and there have been controversies concerning their discovery. Some of the new methods which have been developed and used in these studies will be described. The prospects for production of still heavier elements will be considered.
Date: May 1, 1990
Creator: Hoffman, D.C.
Partner: UNT Libraries Government Documents Department

A new method for picosecond lifetime measurements using electronic timing: Nuclear structure applications

Description: A technique to measure the lifetimes of nuclear states with half lives <10 ps has been developed in conjunction with the TRISTAN mass separator at the High Flux Beam Reactor at BNL. The method uses fast plastic and BaF{sub 2} scintillators and Ge detectors in a triple coincidence ({beta}-{gamma}-{gamma}) fast-slow counting system. The timing information is derived from the fast plastic-BaF{sub 2} coincidence, while the higher resolution of the Ge detector (in slow coincidence) serves to insure that the {beta}-{gamma} event lies in the cascade of interest. The calibrations and corrections necessary to achieve precise results and the methods of data reduction and results from recent measurements on the A = 97 mass chain are presented. 11 refs., 7 figs.
Date: January 1, 1990
Creator: Gill, R.L.
Partner: UNT Libraries Government Documents Department

Precision measurement of the half-life of sup 56 Co

Description: Gamma rays from a mixed source of {sup 56}Co + {sup 46}Sc were measured in a Ge(Li) detector. The {sup 56}Co/{sup 46}Sc intensity ratios I{sub 847}/I{sub 889} were determined by careful analysis of line shapes and underlying backgrounds. Based on the known {sup 46}Sc adopted half-life value of 83.810(10) d, the fit to the intensity ratios corrected for {sup 46}Sc decay from 107 runs over an elapsed time of 172 days gave a half-life of 77.29(3) d. By combining this result with other published data we obtain a half-life of t{sub 1/2} = 77.27(3) d for {sup 56}Co. 16 refs., 3 figs.
Date: January 1, 1990
Creator: Alburger, D.E. (Brookhaven National Lab., Upton, NY (USA)) & Wesselborg, C. (Brookhaven National Lab., Upton, NY (USA) Giessen Univ. (Germany, F.R.). Inst. fuer Kernphysik)
Partner: UNT Libraries Government Documents Department

Single particle states in the heaviest known nuclei

Description: Neutron single-particle states above the N=152 subshell have been studied by high-resolution (d,p) reaction on a {sup 250}Cf target. All of the orbitals between N=152 and N=164 subshells have been identified. A tentative assignment has been made for the 1/2-(750) Nilsson state. 10 refs.
Date: January 1, 1990
Creator: Ahmad, I.; Chasman, R.R.; Friedman, A.M. (Argonne National Lab., IL (USA)) & Yates, S.W. (Kentucky Univ., Lexington, KY (USA))
Partner: UNT Libraries Government Documents Department