Precise measurement of the K-shell internal conversion coefficient of the 344-kev, E2 transition in Gd152

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Schupp, Guy
Hatch, E.
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Ames National Laboratory

Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.

For more than 70 years, the Ames National Laboratory has successfully partnered with Iowa State University, and is unique among the 17 DOE laboratories in that it is physically located on the campus of a major research university. Many of the scientists and administrators at the Laboratory also hold faculty positions at the University and the Laboratory has access to both undergraduate and graduate student talent.

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A value of 0. 0283 ± 0. 0008 was obtained for the K- shell internal conversion coefficient, aK, of the 344-kev, E2 transition in Gd152 using an electron-electron coincidence method. This value is relative to a value of 1.135 ± 0. 010 for the total internal conversion coefficient, a, of the 122-kev, E2 transition in Sm152 . a.K/a ratios of 0. 786 ± 0. 004 and 0. 589 ± 0. 003 were measured for the 344- and 122-kev transitions, respectively. The apparent 9% discrepancy with theory for aK of the 344-kev transition is not explained. The result is in excellent agreement with another measurement and also in agreement with an apparent lower trend for aK's of E2 transitions in near spherical nuclei. The aK value for the 122-kev transition is in good agreement with theory. Additional measurements were performed on the 123- and 87-kev, E2 transitions in Gd154 and Dy160, respectively, and aK/a ratios of 0. 531 ± 0. 007 and 0. 341 ± 0. 011 were obtained. Construction and performance of the beta-ray spectrometers used in these coincidence measurements are described along with limitations of the experimental technique.

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