Absolute Gamma Ray Abundances of Rhenium and Tungsten Isotopes: Part III,A = 173

The decays of 168-174 w were observed in the reactions of 36Ar and 4~ beams with enriched targets of 136BaF2 and 138BaF2" The measured half-lives are 53 (2) s, 76 (6) s, 2.42(4) min, 2.38(4) rain, 6.6(9) min, 6.3(4) rain, and 35.3(5) rain, respectively. Decay schemes were derived from the 7-and X-ray coincidence data. Spin assignments of ground-and excited states are discussed within experimental level systematics and compared with the results of microscopic-macroscopic model calculations. Excitation energies of modeled one-quasiparticle states were found in reasonable agreement with the experimental data. Allowed unhindered beta decay from the 5/2-[523] to the 7/2-[523] configuration was identified in lVlW and this transition is also proposed for the decays of the even-even isotopes 168, 1vow. PACS: 27.70. + q for half-life measurements. Coincidence data from a standard fast-slow coincidence set-up connecting the 7-and X-ray detector were recorded in list-mode on magnetic tape. Each coincidence event was also tagged with the time elapsed since the last tape movement. Identification of the isotopes ~7-,TS wThe isotopes 167-171W were identified by the measurement of excitation functions of new 7-rays and comparison with those of the ~33Cs(S6Ar, xn)169-XTa reactions ( Fig. 1 a). The evaporation of 3 <_ x < 6 neutrons yielded the well known ?-rays 396, 211, 163, and 159 keV from ~6a-~~176 decays. Gamma rays following the decays of tungsten isotopes were selected by requiring coincidence with tantalum X-rays. Excitation functions of tungsten 7-rays using a ~36Ba target are given in Fig. lb. The comparison in Fig. 1 of the measured yields for 94.4, 178.5, and 169.5 keV ?-rays gives the assignment of these lines to the decays of the nuclei 167W [4], ~68W, and 169W, respectively. Accordingly, the y-rays with energies 316.2 and 184.2 keV, which were observed in 36Ar on ~38Ba reactn .4-r-._d K. oq o~ >-a) 133[s (36Ar,xn)169-XTa 211 keV :~=Ta 163 keV ~5Ta / 10 ~ .... ~6s~ \

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Absolute Gamma Ray Abundances of Rhenium and Tungsten Isotopes: Part III,A = 173

Cited by 7 publications

References 4 publications

Fusion-Evaporation Reactions

Fusion-Evaporation Reactions

Summary and Outlook

Investigation of neutron-deficient tungsten isotopes168?174W

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