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Analysis of factors limiting the geometric resolution of a positron imaging device

Description: Large-area, positron-sensitive detectors are used in annihilation coincidence systems for studies with positron-decay radiopharmaceuticals. Factors which limit the spatial resolution in such systems are analyzed. These factors include: (1) the intrinsic spatial resolution of the detector, (2) parallax errors, (3) range of positrons in tissue, and (4) angular deviation of the coincident photon pair from colinearity.
Date: January 1, 1978
Creator: Atkins, F.B.; Harper, P.V. & Beck, R.N.
Partner: UNT Libraries Government Documents Department

High resolution positron Q-value measurements and nuclear structure studies far from the stability line. Progress report

Description: Research progress in briefly described, and details are presented in the attached preprints and reprints: (1) precision mass differences in light rubidium and krypton isotopes utilizing beta endpoint measurements; (2) precision mass measurements utilizing beta endpoints; (3) Monte Carlo calculations predicting the response of intrinsic GE detectors to electrons and positrons; and (4) reactor antineutrino spectra and nuclear spectroscopy of isotopes far from beta stability. (WHK)
Date: February 28, 1982
Creator: Avignone, F.T. III
Partner: UNT Libraries Government Documents Department

Advances in the helium-jet coupled on-line mass separator RAMA. [Recoil Atom Mass Analyzer]

Description: General improvements to the on-line mass separator RAMA (Recoil Atom Mass Analyzer) have yielded a greater reliability and efficiency for some elements. A new utilitarian helium-jet chamber has been installed to facilitate quick target and degrader foil changes in addition to a new ion source holder. A higher efficiency hollow-cathode, cathode-extraction ion source, for lower melting point elements (< 1200/sup 0/C) has also been designed. Tests with the beta-delayed proton emitter /sup 37/Ca showed a factor of five increase in yield over the old hollow-cathode, anode-extraction source. A differentially-pumped-tape drive system compatible with both ..gamma..-..gamma.. and ..beta..-..gamma.. experiments has been incorporated into the general detection system. All major operating parameters will soon be monitored by a complete stand-alone microprocessor system which will eventually be upgraded to a closed-loop control system.
Date: January 1, 1980
Creator: Moltz, D M; Aysto, J; Cable, M D; Parry, R F; Haustein, P E; Wouters, J M et al.
Partner: UNT Libraries Government Documents Department

/sup 18/F-4-fluoroantipyrine

Description: The novel radioactive compound /sup 18/F-4-fluoroantipyrine having high specific activity which can be used in nuclear medicine in diagnostic applications, prepared by the direct fluorination of antipyrine in acetic acid with radioactive fluorine at room temperature and purifying said radioactive compound by means of gel chromatography with ethyl acetate as eluent is disclosed. The non-radioactive 4-fluoroantipyrine can also be prepared by the direct fluorination of antipyrine in acetic acid with molecular fluorine at room temperature and purified by means of gel chromatography with ethyl acetate eluent.
Date: January 1, 1980
Creator: Shiue, C.Y. & Wolf, A.P.
Partner: UNT Libraries Government Documents Department

Design of a /sup 18/F production system at ORNL 86-inch cyclotron

Description: A target system for the production of /sup 18/F by proton bombardment of H/sub 2//sup 18/O was designed for the ORNL 86-inch cyclotron facility. The system consists of concentric titanium and aluminum cylinders. Oxygen-18-enriched H/sub 2/O circulates through the inner titanium cylinder and through an external heat exchanger with cooling water flowing in the annulus. Yields of 5.0 curies are expected for a 250-..mu..A proton beam current and 24-min irradiation time.
Date: October 19, 1977
Creator: Shaeffer, M.C.; Barreto, F.; Datesh, J.R. & Goldstein, B.R.
Partner: UNT Libraries Government Documents Department

Superdeformed bands in sup 194 Tl

Description: Superdeformation was first observed in the mass-190 region in {sup 191}Hg. Since then, SD bands have been found in {sup 190-194}Hg nuclei. Here we report the discovery of two such bands in {sup 194}Tl which are the first SD bands fond in this mass region that are not in Hg nuclei. Subsequently, bands have been found in two Pb nuclei. 5 refs., 1 fig.
Date: May 1, 1990
Creator: Azaiez, F.; Kelly, W.H.; Korten, W.; Deleplanque, M.A.; Stephens, F.S.; Diamond, R.M. et al.
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

Models for Type I supernovae

Description: Two rather disjoint scenarios for Type I supernovae are presented. One is based upon mass accretion by a white dwarf in a binary system. The second involves a star having some 8 to 10 times the mass of the sun which may or may not be a solitary star. Despite the apparent dissimilarities in the models it may be that each occurs to some extent in nature for they both share the possibility of producing substantial quantities of /sup 56/Ni and explosions in stars devoid of hydrogen envelopes. These are believed to be two properties that must be shared by any viable Type I model.
Date: June 17, 1980
Creator: Woosley, S.E.; Weaver, T.A. & Taam, R.E.
Partner: UNT Libraries Government Documents Department

Analytic and experimental decay heat determinations of 800-MeV proton irradiated aluminum

Description: Postirradiation radiochemistry analysis of 800-MeV proton irradiated ultrahigh purity aluminum has been done with standard gamma-ray counting equipment determining the Na/sup 22/ activity in the activated aluminum. Results are compared to predicted values obtained from CINDER, a general nuclide depletion and fission-product code. This program can be used easily to calculate the activity of materials under arbitrary irradiation, provided that the source terms for the various radionuclides produced are known. The required production cross sections have been calculated by using the nucleon-meson transport code NMTC to determine the nuclear reactions produced by the protons, and the theory of Lindhard et al. to evaluate the resultant damage energy deposited in the target.
Date: October 1, 1981
Creator: Kmetyk, L.N. & Sommer, W.F.
Partner: UNT Libraries Government Documents Department

Electromagnetic properties of sup 181 Ir: Evidence of. beta. -stretching

Description: We have calculated the B(Ml)/B(E2) ratios in {sup 18l}Ir within a shape-fixed particle + rotor model, in order to investigate how sensitive these may be to the nuclear shapes under consideration, and whether or not there is evidence of shape coexistence in the electromagnetic data alone. The model calculations employed the same Woods-Saxon potential that has been used previously for TRS and bandhead calculations and all parameters have been taken at their standard values, without any adjustments. To the extent possible with present models, these calculations should represent predictions for the B(M1)/B(E2) ratios at the deformations expected from the TRS and bandhead calculations. A comparison with the {sup 181}Ir data is stimulated by the fact that this is the lightest-mass Ir nucleus for which the spins and parities am firmly established experimentally; we find that the electromagnetic transition rates in this nucleus are well reproduced under the assumption of a single, fixed shape.
Date: January 1, 1991
Creator: Garg, U.; Reviol, W. (Notre Dame Univ., IN (United States). Dept. of Physics) & Semmes, P. (Tennessee Technological Univ., Cookeville, TN (United States). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

Superdeformation in the mercury nuclei

Description: We shall first summarize the present experimental situation concerning {sup 192}Hg, the nucleus regarded as the analog of {sup 152}Dy for this superdeformation (SD) region in that gaps are calculated to occur at large deformation for Z = 80 and N = 112. Proton and neutron excitations out of the {sup 192}Hg core will then be reviewed with particular emphasis on {sup 191}Hg and {sup 193}Tl. The presentation will conclude with a brief discussion on limits of the SD region for neutron deficient Hg nuclei. 26 refs., 10 figs.
Date: January 1, 1990
Creator: Janssens, R.V.F.; Carpenter, M.P.; Fernandez, P.B.; Moore, E.F.; Ahmad, I.; Khoo, T.L. et al.
Partner: UNT Libraries Government Documents Department

Calculated late time spectra of supernovae

Description: We consider here the nebular phase spectra of supernovae whose late time luminosity is provided by the radioactive decay of /sup 56/Ni and /sup 56/Co synthesized in the explosion. A broad variety of supernovae are known or suspected to fall in this category. This includes all SNIa and SNIb, and at least some SNII, in particular SN1987a. At sufficiently late times the expanding supernova becomes basically nebular in character due to its decreasing optical depth. The spectra produced during this stage contain information on the density and abundance structure of the entire supernova, as opposed to spectra near maximum light which are affected only by the outermost layers. A numerical model for nebular spectrum formation is therefore potentially very valuable for answering currently outstanding questions about the post-explosion supernova structure. As an example, we can hope to determine the degree of mixing which occurs between the layers of the ''onion-skin'' abundance structure predicted by current one dimensional explosion calculations. In the sections which follow, such a numerical model is briefly described and then applied to SN1972e, a typical SNIa, SN1985f, an SNIb, and finally to SN1987a. In the case of SN1987a predicted spectra are presented for the wavelength range from 1 to 100 microns at a time 300 days after explosion. 18 refs., 6 figs.
Date: October 30, 1987
Creator: Axelrod, T.S.
Partner: UNT Libraries Government Documents Department

Mapping of functional activity in brain with /sup 18/F-fluoro-deoxyglucose

Description: A model has been designed based on the assumptions of a steady state for glucose consumption, a first-order equilibration of the free /sup 14/C-DG pool in the tissue with the plasma level, and relative rates of phosphorylation of /sup 14/C-DG and glucose determined by their kinetic constants for hexokinase reaction. Using an operational equation based on this model, the metabolic rates of glucose are calculated in various regions of brain (utilizing brain slices and autoradiography). /sup 14/C is a beta emitter and therefore not suitable for noninvasive imaging in man. With the synthesis of /sup 18/F-2-deoxy-2-fluoro-D-glucose (/sup 18/F-DG) all of the requirements for a suitable radiopharmaceutical for the determination of local cerebral metabolism have been met. This agent behaves very similarly to /sup 14/C-DG and therefore, using the above described model and emission tomography, it has become possible to measure regional cerebral metabolism for the first time in man.
Date: January 1, 1981
Creator: Alavi, A.; Reivich, M.; Greenberg, J. & Wolf, A.
Partner: UNT Libraries Government Documents Department

Uptake and distribution of technetium in several marine algae

Description: The uptake or chemical form of technetium in different marine algae (Acetabularia, Cystoseira, Fucus) has been examined and a simple model to explain the uptake of technetium in the unicellular alga, Acetabularia, has been conceptualized. At low concentrations in the external medium, Acetabularia can rapidly concentrate technetium. Concentration factors in excess of 400 can be attained after a time of about 3 weeks. At higher mass concentrations in the medium, uptake of technetium by Acetabularia becomes saturated resulting in a decreased concentration factor (approximately 10 after 4 weeks). Approximately 69% of the total radioactivity present in /sup 95m/Tc labelled Acetabularia is found in the cell cytosol. In Fucus vesiculosus, labelled with /sup 95m/Tc, a high percentage of technetium is present in soluble ionic forms while approximately 40% is bound, in this brown alga, in proteins and polysaccharides associated with cell walls. In the algal cytosol of Fucus vesiculosus, about 45% of the /sup 95m/Tc appears to be present as anionic TcO/sup -//sub 4/ and the remainder is bound to small molecules. 8 references, 5 figures, 1 table.
Date: January 1, 1983
Creator: Bonotto, S.; Gerber, G.B.; Garten, C.T. Jr.; Vandecasteele, C.M.; Myttenaere, C.; Van Baelen, J. et al.
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

1-/sup 11/C-D-glucose and related compounds

Description: The novel compounds 1-/sup 11/C-D-glucose, 1-/sup 11/C-D-mannose, 1-/sup 11/C-D-galactose, 2-/sup 11/C-D-glucose, 2-/sup 11/C-D-mannose and 2-/sup 11/C-D-galactose which can be used in nuclear medicine to monitor the metabolism of glucose and galactose can be rapidly prepared by reaction of the appropriate aldose substrate with an alkali metal /sup 11/C-labeled cyanide followed by reduction with a Raney alloy in formic acid.
Date: January 26, 1982
Creator: Shiue, C.Y. & Wolf, A.P.
Partner: UNT Libraries Government Documents Department

Alumina column Rb-82 generator

Description: The use of an alumina column for the adsorption of radioactive Sr for the generator production of 75-sec /sup 82/Rb was evaluated in both batches and column experiments using /sup 85/Sr and cyclotron-produced /sup 82/Sr. Comparisons of alumina, Bio-Rex 70 and Chelex 100 ion exchangers were made to determine Sr adsorption, /sup 82/Rb elution yield and Sr breakthrough. The adsorption of Sr is similar for alumina and Chelex 100 but different for Bio-Rex 70. Alumina and Chelex 100 exhibit a small fraction of poorly bound Sr which appears as higher breakthrough in the early elution volumes. The remaining Sr activity is strongly bound to these ion exchangers and the breakthrough remains stable at a lower breakthrough value through a large number of elutions. Bio-Rex 70 on the other hand does not exhibit the poorly bound Sr fraction and the breakthrough of Sr remains the lowest of the three ion exchangers through a moderate number of elutions and then the Sr breakthrough gradually increases with each additional elution.
Date: October 1, 1977
Creator: Yano, Y. & Roth, E.P.
Partner: UNT Libraries Government Documents Department

Results of the /sup 37/Cl experiment

Description: Present results of the /sup 37/Cl experiment to measure the flux of /sup 8/B neutrinos from the sun are presented. The results are plotted, and the technical details are discussed. From a /sup 37/Ar production rate above the background of 0.30, the possible solar neutrino rate was deduced to be 5.31 x (0.30 +- 0.08) = 1.6 +- 0.4 SNU. (JFP)
Date: unknown
Creator: Davis, R Jr
Partner: UNT Libraries Government Documents Department

The GAMMASPHERE

Description: GAMMASPHERE is one of a new generation of gamma ray detector arrays. It consists of 100 Compton-suppressed large volume Ge detectors. The design goal is to achieve high efficiency and peak-to-total value for four to five fold coincidence experiments. Such high-fold coincidence capability will provide new physics opportunities in areas such as high spins, transfer reactions, giant resonances, and astrophysics. The design of the detector and shield has been developed through extensive simulation calculations and an electronic honeycomb'' design was chosen. The electronics and computer systems are capable of operating at 50,000 event/sec. The design and development tasks are being carried out at several laboratories in the US GAMMASPHERE will sited initially at the 88-Inch Cyclotron at LBL as a national facility. The first experiment is planned in early 1993. 7 refs., 7 figs., 2 tabs.
Date: January 1, 1991
Creator: Lee, I-Yang.
Partner: UNT Libraries Government Documents Department

Androgen receptor-based imaging agents for the prostate: Synthesis and tissue distribution studies with tritium and fluorine-18 labeled androgens

Description: Short communication.
Date: January 1, 1990
Creator: Liu, A.; Carlson, K.E.; Katzenellenbogen, J.A. (Illinois Univ., Urbana, IL (United States). Dept. of Chemistry); VanBrocklin, H.F.; Mathias, C.J. & Welch, M.J. (Washington Univ., St. Louis, MO (United States). Edward Mallinckrodt Inst. of Radiology)
Partner: UNT Libraries Government Documents Department

Deoxyglucose method for the estimation of local myocardial glucose metabolism with positron computed tomography

Description: The deoxyglucose method originally developed for measurements of the local cerebral metabolic rate for glucose has been investigated in terms of its application to studies of the heart with positron computed tomography (PCT) and FDG. Studies were performed in dogs to measure the tissue kinetics of FDG with PCT and by direct arterial-venous sampling. The operational equation developed in our laboratory as an extension of the Sokoloff model was used to analyze the data. The FDG method accurately predicted the true MMRGlc even when the glucose metabolic rate was normal but myocardial blood flow (MBF) was elevated 5 times the control value or when metabolism was reduced to 10% of normal and MBF increased 5 times normal. Improvements in PCT resolution are required to improve the accuracy of the estimates of the rate constants and the MMRGlc.
Date: January 1, 1981
Creator: Ratib, O.; Phelps, M.E.; Huang, S.C.; Henze, E.; Selin, C.E. & Schelbert, H.R.
Partner: UNT Libraries Government Documents Department

Development and applications of the positron microscope

Description: Progress on the positron microscope during the past year has been steady, and we currently project that initial microscope images can be collected during mid to late summer of 1992. Work during the year has mainly been divided among four areas of effort: hardware construction; power supply and control system development; radioactive source fabrication; and planning of initial experimental projects. Details of progress in these areas will be given below. An initial optical design of the microscope was completed during 1990, but during the past year, significant improvements have been made to this design, and several limiting cases of microscope performance have been evaluated. The results of these evaluations have been extremely encouraging, giving us strong indications that the optical performance of the microscope will be better than originally anticipated. In particular, we should be able to explore ultimate performance capabilities of positron microscopy using our currently planned optical system, with improvements only in the image detector system, and the positron-source/moderator configuration. We should be able to study imaging reemission microscopy with resolutions approaching 10 {Angstrom} and be able to produce beam spots for rastered microscope work with diameters below the 1000 {Angstrom} diffusion limit. Because of these exciting new possibilities, we have decided to upgrade several microscope subsystems to levels consistent with ultimate performance earlier in our construction schedule than we had previously intended. In particular, alignment facilities in the optical system, vibration isolation, and power supply and control system flexibility have all been upgraded in their design over the past year.
Date: January 1, 1991
Partner: UNT Libraries Government Documents Department

High-spin configurations in /sup 147/Gd from alignment of seven, nine, and eleven particles

Description: Detailed spectroscopic studies of the discrete ..gamma..-rays feeding the 550-ns isomer at 8.590 MeV in /sup 147/Gd are reported. The resulting decay scheme indicates single-particle nature of the states up to the highest observed spin 79/2 h at 16.938 MeV of excitation energy. Comparison with Deformed Independent Particle Model calculations makes it possible to suggest configuration assignments to many of the levels. Five neutrons and six protons with their angular momenta aligned form the highest yrast states.
Date: January 1, 1983
Creator: Sletten, G.; Bjornholm, S. & Borggreen, J.
Partner: UNT Libraries Government Documents Department

The excitation function for /sup 48/V from tritons on natural titanium

Description: Natural titanium is used as a diagnostic charged particle detector in nuclear device tests making use of the proton and deuteron reactions, which produce vanadium 48 as a product. The presence of tritons in the reaction environment can also produce vanadium 48 from triton reactions on titanium 3, titanium 47 and titanium 48. Triton reaction cross sections for titanium have been measured so that corrections to the proton and deuteron diagnostic data can be accurately calculated. These measurements were made using the Van de Graaff at the Los Alamos National Laboratory.
Date: May 5, 1987
Creator: West, H.I. Jr.; Lanier, R.G.; Mustafa, M.G. & O'Brien, H.
Partner: UNT Libraries Government Documents Department