LIFETIMES OF 4+ AND 2+ STATES IN THE ROTATIONAL NUCLEI Dy$sup 162$, Er$sup 166$, Er$sup 168$, AND Hf$sup 18$$sup 0$
Lifetimes of the first 2 excited states (the 2+ and 4+ states) were determined for the even-proton even-neutron nuclei of Dy/sup 162/, Er/sup 166/, Er/sup 168/, and Hf/sup 180/. These are li fetimes of the order of a 10/sup -9/ and 10/sup -10/ sec. The measurements were undertaken to test the predictions of the strong coupling model, according to which these states are classified as members of the ground state rotational band of strongly deformed nuclei. The lifetime measurements were made by the delayed coincidence method. A description is given of this method and of the associated circuitry. Two methods commonly used to analyze delayed coincidence data are the slope method'' and the centroid shift method.'' The mathematical description of these methods is given, and the relative merits of the methods are discussed. All the half lives except that of the Hf/sup 180/ 4+ state were determined from the exponential slopes of their respective delayed coincidence time spectra. For the Hf/sup 180/ 4+ state, a centroid shift measurement was necessary because this lifetime is 30% shorter than any of the others. Details of the individual measurements are given and results are presented. From each of the lifetimes, a reduced transition probability B(E2; 1 + 2 yields I) is calculated (I being the spin of the state). The ratios B(E2; 4 yields 2)/ B(E2; 2 yields O) for the 4 nuclei are found to be the following: Dy/sup 162/, 1.42. Er/sup 166/, 1.42; Er/sup 169/, 1.46; and Hf/sup 180/, 1.45. These are evidently in excellent agreement with the expected ratio of 10/7, and the predictions of the strong coupling model are seen to be verified. (M.P.G.) 1963. 58p.
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-18-009435
- OSTI ID:
- 4087558
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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