PHOTONEUTRON CROSS SECTIONS OF Tb$sup 159$ AND O$sup 1$sup 6$PHOTONEUTRON CROSS SECTIONS OF Tb$sup 159$AND O$sup 1$sup 6$

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 Author Bramblett, R. L. ♦ Caldwell, J. T. ♦ Harvey, R. R. ♦ Fultz, S. C. Source United States Department of Energy Office of Scientific and Technical Information Content type Text Language English
 Subject Keyword PHYSICS ♦ ANNIHILATION ♦ COUNTERS ♦ CROSS SECTIONS ♦ ELECTRIC MOMENTS ♦ ENERGY LEVELS ♦ GAMMA RADIATION ♦ MEASURED VALUES ♦ NEUTRON DETECTION ♦ NUCLEAR MODELS ♦ OXYGEN 16 ♦ PHOTONEUTRONS ♦ POSITRONS ♦ RESOLUTION ♦ RESONANCE ♦ STATISTICS ♦ TERBIUM 159 Abstract The photoneutron cross sections of O/sup 16/ and Tb/sup 159/ were measured up to 30 Mlev using photons of 3% resolution resulting from positron annihilation-in-flight. Thirteen resonances corresponding to levels in O/sup 16/ were observed in the O/sup 16/ ( gamma ,n) reaction. One, at 29 plus or minus 1 Mev, is previously unreported. The O/sup 16/( gamma ,n) cross section integrated to 30 Mev is 46 plus or minus 5 Mev-mb. Both the ( gamma ,n) and ( gamma ,2n) cross sections of Tb were measured using a statistical counting technique. The ratio of the two cross sections determines that the level density parameter, a = 17 plus or minus 5 (Mev)/sup -1/. The sum of the ( gamma ,n) and ( gamma ,2n) cross sections is a double peaked giant E1 resonance, from which the intrinsic quadrupole moment was determined to be 7.0 plus or minus 1.1 b. Additional structure in the Tb/sup 159/( gamma ,n) cross section was observed at 10.1 Mev. The sum of the ( gamma ,n) and ( gamma ,2n) cross sections of Tb/sup 159/, integrated to 28 Mev, is 2.3 plus or minus 0.2 Mev-b. (auth) ISSN 0031899X Educational Use Research Learning Resource Type Article Publisher Date 1964-02-24 Publisher Department Univ. of California, Livermore Publisher Place United States Journal Physical Review Volume Number 133 Technical Publication No. UCRL-7156 Organization Univ. of California, Livermore