Common thresholds and the role of deformations in the photoexcitation of isomers

Journal Article · Tue Dec 01 04:00:00 EST 1992 · Bulletin of the American Physical Society

OSTI ID:127879

Carroll, J J; Collins, C B; Taylor, K N ^[1]

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1. Univ. of Texas, Dallas, TX (United States); and others

The photoexcitation of the isomers of {sup 167}Er, {sup 179}Hf, {sup 191}Ir and {sup 197}Au by ({gamma},{gamma}{prime}) reactions was studied using bremsstrahlung from the injector to the superconducting Darmstadt linear accelerator. Over 1800 irradiations were performed to determine the excitation energies of gateway states mediating the reactions in the range from 2 to 5 MeV. Incident photon spectra were characterized with the EGS4 coupled electron-photon transport code and were cross-checked against the calibration reaction {sup 115}In({gamma},{gamma}{prime}){sup 115}In{sup m}. Large integrated cross sections of the gateway levels were obtained with values which varied from 10{sup {minus}26} to 10{sup {minus}25} cm{sup 2} keV, on the same order-of-magnitude as those found for intermediate states for the deexcitation reaction {sup 180}Ta{sup m}({gamma},{gamma}{prime}){sup 180}Ta studied previously. The reduced transition probabilities deduced from these measurements show a clear correlation with the ground-state deformations of the nuclides. The slow variation of gateway parameters for nuclei neighboring {sup 180}Ta provides important support to models for an optically pumped gamma-ray laser.

• OSTI ID: 127879
• Report Number(s): CONF-920376--
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 9 Vol. 37; ISSN BAPSA6; ISSN 0003-0503
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ERBIUM 167 TARGET
EXCITATION
GOLD 197 TARGET
HAFNIUM 179 TARGET
IRIDIUM 191 TARGET
ISOMERIC NUCLEI
MEV RANGE 01-10
NUCLEAR DEFORMATION
PHOTONUCLEAR REACTIONS
THRESHOLD ENERGY