ISOMERIC CROSS-SECTION RATIOS IN (n,$gamma$) REACTIONS
ABS>Isomeric cross-section ratios for (n, gamma ) reactions have been measured for the even-even target nuclei Te/sup 120/, Te/sup 130/, Ce/sup 138/, Pt/sup 196/, and Hg/sup 196/. In addition, cross sections for Pt/sup 194/(n, gamma )Pt/sup 195m/ and Pt/sup 192/(n, gamma /)Pt/sup 193m/ reactions hav e also been measured. It is found that isomeric cross-section ratios ( sigma /sub low spin// sigma /sub high spin/) tend to increase at the magic numbers of neutrons as well as protons. Away from the magic numbers, these ratios obey an empirical rule which states, The isomeric cross-section ratios for various isotopes in the same element remain approximately the same provided the spins of the compound nuclei and the isomeric stntes are the same for all the isotopes.'' This rule applies to even-even target nuclei. On the basis of this new empirical rule, the cross sections for the production of some of the isomeric states have been estimated. Multiplicity factors (i.e., the number of gamma rays emitted per neutron capture by target nuclei) have been calculated for A < 100, using capture gamma spectra of Groshev et al. Theoretical calculations of the isomeric cross- section ratios are performed using the spin dependence of the nuclear level density expression of Bloch. Experimental values of the isomeric cross-section ratios are compared with the theoretical values and the results are discussed. (auth)
- Research Organization:
- Brookhaven National Lab., Upton, N.Y.
- NSA Number:
- NSA-17-000832
- OSTI ID:
- 4770144
- Report Number(s):
- BNL-6135; 0031-899X
- Journal Information:
- Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Vol. Vol: 128; Other Information: BNL-6135. Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- United States
- Language:
- English
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