Nuclear Data Sheets for A = 193

Investigation of excited levels in 193Ir from the beta decay of 193Os

“…The levels at 517, 563 and 621 keV, known only from other reactions [1], were positively identified in the present experiment.…”

“…also, the suspicion that the two levels at 848.9 and 849.1 keV were the same, reported in the ENSDF Adopted Levels for 193 Ir [1], was positively confirmed. On the other hand, four known transitions were not seen in this experiment; the 80 keV transition that depopulates the 80 keV isomer (T 1/2 ≈10d) wasn't seen because of its very long half-life; the 41 keV transition that depopulates the 180 keV level was below the energy threshold for this experiment (≈55 keV); the 486 keV transition that depopulates the level at 559 keV would only be coincident to the 73 keV transition, which is strongly contaminated by the 73.6 keV Ir K β1 X-Ray or to very weak transitions (I≤0.05%), so it couldn't be positively identified; finally, the 338 keV transition that depopulates the level at 1078 keV couldn't be identified either, but in fact this very weak transition has never been seen in a β − decay experiment before, and is just assumed to be there because it was seen depopulating a level known to be populated by the β decay in the 191 Ir(nn,γ) experiment [1,13]. The 27 radiations seen for the first time in this work, together with the 2 tentatively-positioned ones, are presented in Table I, together with their placement, as deduced from the present γ − γ coincidence analysis.…”

“…Most of the γ-ray intensities were taken from a previous singles spectroscopy experiment [10,11]; in the cases where the spectroscopy results didn't agree (within 2σ) with the reference values from [1], when the transition hadn't been seen in the spectroscopy experiment, and also for every new transition, I(γ) was calculated from γ − γ coincidence analysis by assuming that ∑ AB,AC...CD W (θ) k, where k is constant for all transitions, regardless of their multipolarity and mixing ratio; this would be true if the detectors covered 4π -in the present case, the assumption was tested on several well-established transitions, and the values obtained were in excellent agreement with the expected ones. This way, if two gamma transitions γ 1 and γ 2 are in direct coincidence with a third one γ 3 (i.e., there are no intermediate transitions between γ 1 and γ 3 or between γ 2 and γ 3 ); then: where A(i j) is the area of the coincidence photopeak for the pair γ i × γ j and ε(i j) is the sum of the detection efficiencies of all six detector pairs for the cascade.…”

“…(3) 879.48 (6) e 598.168(7) 418.31 (7) a 0.012 (7) 879.48 (6) e 460.541(4) 283.97 (7) a 0.028 (3) 882.14 (7) e 598.168(7) 292.19 (7) a 0.0170(24) 890.36 (7) e 598.168 (7) 361.51 (3) a 0.083 (7) 959.68 (18) e 598.168 (7) TABLE I: Gamma radiations seen or placed for the first time in this experiment; I γ is the relative gamma-ray intensity (the intensity of the gamma-ray at 460.550 keV is considered as 100%); E i and E f are the excitation energies of the initial and final levels for that transition, respectively. i Intensity value couldn't be independently obtained from experimental data, so a limit was estimated using ENSDF adopted branching ratio [1]; t Tentative placement; nd The intensity of this transition could not be determined.…”

“…In the ENSDF Adopted Levels for 193 Ir [1], there was the suspicion that the two levels at 848.93 keV and 849.083 keV could be the same, but as the latter was seen only in the 191 Ir(nn,γ) experiment [13], which only studied E γ < 700 keV, and the former was only known to be depopulated by transitions above that energy (710, 776 and 849 keV), if the two transitions found to depopulate the 848.93 keV level in the (nn,γ) experiment were too weak in comparison to the other ones, they could have remained unseen in the other experiments and thus the levels couldn't be positively identified to be the same.…”