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New isotopes of interest to explosive nucleosynthesis. [J,. pi. , preliminary results]

Description: A number of new isotopes in the iron region, both neutron-rich and proton-rich, have been produced at the Argonne FN tandem using heavy-ion beams. On the neutron-rich side, masses and beta-decay schemes were obtained, and the masses will be compared with various mass formulae used in nucleosynthesis calculations. Several heavy proton-rich N = Z odd-odd nuclei extending up from /sup 62/Ga were investigated with the aim of measuring the ft-values of their superallowed Fermi decays. The resulting ft-values will be compared with those found for the well studied lighter nuclei between /sup 14/O and /sup 54/Co. 11 references
Date: January 1, 1978
Creator: Davids, C.N.
Partner: UNT Libraries Government Documents Department

Harvard--MIT research program in short-lived radiopharmaceuticals. Progress report, September 1, 1977--April 30, 1978. [/sup 99m/Tc, positron-emitting radionuclides]

Description: Progress is reported on the following studies: chemistry studies designed to achieve a more complete understanding of the fundamental chemistry of technetium in order to facilitate the design of future radiopharmaceuticals incorporating the radionuclide /sup 99m/Tc; the development of new radiopharmaceuticals intended to improve image quality and lower radiation doses by the use of short-lived radionuclides and disease-specific agents; the development of short-lived positron-emitting radionuclides which offer advantages in transverse section imaging of regional physiological processes; and studies of the toxic effects of particulate radiation.
Date: May 1, 1978
Creator: Adelstein, S.J. & Brownell, G.L.
Partner: UNT Libraries Government Documents Department

Stereoselective disposition of R-(-)- and S-(+)-methadone in man

Description: Deuterium-labeled methadone has been used to study the urinary excretion of racemic methadone, R-(-)- and S-(+)-methadone in adult maintenance patients. In three cases studied, the pharmacologically active enantiomer, R-(-)-methadone, had a significantly longer elimination half-life (51.7 to 61.8 hours) than did the inactive S-(+)-methadone (31.8 to 37.0 hours). The ratio of drug elimination half-lives, R-(-)-/S-(+)-, ranged between 1.39 and 1.94.
Date: January 1, 1978
Creator: Hachey, D.L.; Kreek, M.J. & Klein, P.D.
Partner: UNT Libraries Government Documents Department

Analytical methods for fissionable material determinations in the nuclear fuel cycle. Progress report, October 1, 1976--September 30, 1977

Description: Development of dissolution techniques for difficult-to-dissolve nuclear materials, development of methods and automated instruments for plutonium and uranium determinations, preparation of plutonium-containing materials for the Safeguards Analytical Laboratory Evaluation (SALE) program, analysis of SALE uranium materials, preparation of certified reference material plutonium metal, measurement of longer plutonium isotope half-lives, and study of ion exchange behavior of elements in various media continued. Gas-solid reaction of carbonyl chloride with uranium-bearing materials at elevated temperature is superior to reaction with chlorine for uranium volatilization and separation. Neither reaction with a variety of nonaqueous solvents nor reaction with molten selenium oxide provides practical dissolution of refractory materials characteristic of nuclear fuel cycle materials. The LASL automated spectrophotometer has been used to determine 0.1-mg amounts without instrumental or procedural changes. A microgram-sensitive spectrophotometric method for uranium has been developed, and the automated spectrophotometer is being modified to its use. A controlled-potential coulometric method has been developed for selective determination of plutonium. An automated analyzer to use this method is being built. Uranium-plutonium mixed oxide powder, for SALE samples, has not remained stable during storage, but high-density pellets have. In a DOE interlaboratory program, the half-life of /sup 239/Pu has been measured, experiments on /sup 241/Pu half-life measurement are in progress, and /sup 240/Pu half-life measurement is planned. Ion exchange distributions for over 50 elements have been measured to determine cation exchange in nitric acid and anion exchange in both hydrobromic and hydriodic acids.
Date: January 1, 1978
Creator: Waterbury, G.R. (comp.)
Partner: UNT Libraries Government Documents Department

Recent searches for superheavy elements at the superhilac. [Cross section limits for Z = 110 to 118]

Description: The results of the search for superheavy elements are negative with respect to the finding of such elements. However, by assuming 2 spontaneous fission events as the lower limit of detection, the limits to their formation cross sections are calculated and plotted. It is noted that the half-life limits, also shown are easily within the huge uncertainties of the theoretical predicted half lives for any superheavy element nuclides produced in the experiment. 19 references. (JFP)
Date: March 28, 1978
Creator: Hulet, E.K.
Partner: UNT Libraries Government Documents Department

Fission properties of einsteinium and fermium. [Half-life, kinetic energy release, mass division, prompt neutron emission]

Description: The systematics of the low energy fission of the fermium isotopes is studied considering half-lives, masss division, kinetic-energy release, and accompanying prompt neutron emission. It is shown that the low energy fission of the fermium isotopes is a microcosm of the fission process, exhibiting a wide range of half lives, mass and kinetic energy distributions and varying neutron emission. The trends in the fermium isotopes are considered. 23 references. (JFP)
Date: January 1, 1978
Creator: Hoffman, D.C.
Partner: UNT Libraries Government Documents Department

Radiochemical studies of neutron deficient actinide isotopes

Description: The production of neutron deficient actinide isotopes in heavy ion reactions was studied using alpha, gamma, x-ray, and spontaneous fission detection systems. A new isotope of berkelium, /sup 242/Bk, was produced with a cross-section of approximately 10 ..mu..b in reactions of boron on uranium and nitrogen on thorium. It decays by electron capture with a half-life of 7.0 +- 1.3 minutes. The alpha-branching ratio for this isotope is less than 1% and the spontaneous fission ratio is less than 0.03%. Studies of (Heavy Ion, pxn) and (Heavy Ion, ..cap alpha..xn) transfer reactions in comparison with (Heavy ion, xn) compound nucleus reactions revealed transfer reaction cross-sections equal to or greater than the compound nucleus yields. The data show that in some cases the yield of an isotope produced via a (H.I.,pxn) or (H.I.,..cap alpha..xn) reaction may be higher than its production via an xn compound nucleus reaction. These results have dire consequences for proponents of the ''Z/sub 1/ + Z/sub 2/ = Z/sub 1+2/'' philosophy. It is no longer acceptable to assume that (H.I.,pxn) and (H.I.,..cap alpha..xn) product yields are of no consequence when studying compound nucleus reactions. No evidence for spontaneous fission decay of /sup 228/Pu, /sup 230/Pu, /sup 232/Cm, or /sup 238/Cf was observed indicating that strictly empirical extrapolations of spontaneous fission half-life data is inadequate for predictions of half-lives for unknown neutron deficient actinide isotopes.
Date: April 1, 1978
Creator: Williams, K.E.
Partner: UNT Libraries Government Documents Department