Nuclear Structure of \(^{122}Xe\) Studied via High-Statistics \(\beta^+/EC\) Decay of \(^{122}Cs\)

Jigmeddorj, Badamsambuu
Journal Title
Journal ISSN
Volume Title
University of Guelph

The Xe isotopes are located at a possible phase change in the collective structure from vibrational to rotational. The Xe isotopes therefore were considered as potential candidates for (\gamma)-soft nuclei or (O(6)) symmetry limit within the IBM. However, testing of the O(6) symmetry in Xe reveals that indeed their structure is more complicated. The study of the nucleus (^{122}Xe) is a part of a systematic examination of the development of collectivity in the Xe isotopes, which are located in the (Z>50), (N<82) region that display an extraordinarily smooth evolution of simple collective signatures. In order to probe the development of collectivity in greater detail, additional information on excited states is required. Specifically, the knowledge of excited states that decay to other excited states resulting low-energy transitions which can give strong indicators of the underlying structure need to be improved. The experiment to study (^{122}Xe) with the (\beta^+/EC) decay of (^{122}Cs) was performed at the TRIUMF-ISAC facility located in Vancouver, B.C., Canada. Radioactive (^{122}Cs) beams from the ISAC facility were delivered to the 8(\pi) spectrometer which was composed of 20 HPGe detectors. The isomeric and ground states of (^{122}Cs) decay to the (^{122}Xe) with half lives of 21 seconds and a 3.7 minutes, respectively. Two sets of high-statistics data for short- and long-half-life decays were collected to have an access for potential excited states of the (^{122}Xe). As an evidence of data quality, the level scheme of (^{122}Xe) has been dramatically extended by 177 new levels and 482 new transitions. Using (\gamma)-(\gamma) angular correlation analysis, 71 spin assignments have been made for 55 levels since a spin of some levels could be assigned via several different cascades. Mixing ratios for 44 (\gamma)-ray transitions were extracted from the angular correlation analysis by extracting the values from the minimized (\chi^2) fit. Branching ratios have been determined for all observed transitions independently in the two different data sets collected with the short and long cycled runs. The data have been compared with a sd-IBM-1 calculation.

Xe-122, beta decay, nuclear structure, Angular Correlation Analysis, level scheme, branching ratios, IBM1, Relative B(E2), Spin assignment