K Conversion Coefficient of the near Threshold M3 Transition in ¹⁹¹Os

Abstract

The K conversion coefficient of the predominantly M3 transition at 74.37 keV in 191Os has been measured to be 75 ± 8. This differs both from the theoretical value of 160 and a recent measurement giving 38.4.

TheK conversion coefficient near threshold of theM3 transition in191Os

“…This result exceeds considerably the value of Kirschner [1] ~k= 7.7 38.4+4.6_ and still differs significantly from the value ~k= 75_+ 8 measured by Campbell et al [2]. Meanwhile Kirschner [3] has remeasured the K conversion coefficient with the result c~/~= 131 _+ 12.…”

“…Both, the late value published by Kirschner [3] (~r=131__12) and the result given by Campbell [2] (c~r= 75+__8) seem to be reliable, but they differ considerably, though they are based on the same experimental method. Uncertainties will be caused by the subtraction of the Os Kfl'z-and the Ir Kfi'tlines from the sum peak to yield the intensity of the weak 74.38 keV y-line, because a decomposition can not be made (Fig.…”

“…An effect of higher order can not be excluded at all and might be an effect of partial interest [2], but a reduction of about 30% in ~k is quite a strong effect.…”

“…The transition energy is only 0.5 keV above the K electron binding energy. Some speculations [1,2] have been made belonging to a steep descent of the M3 K conversion coefficient. Therefore, a precise measurement of the K conversion coefficient ~K tests internal conversion theory in the hitherto unexplored region very close to the energy threshold.…”

“…Until now only results of measurements with Ge(Li) X-ray detectors [1][2][3] used as spectrometers are available. Both, the late value published by Kirschner [3] (~r=131__12) and the result given by Campbell [2] (c~r= 75+__8) seem to be reliable, but they differ considerably, though they are based on the same experimental method.…”