Precise measurement ofαKfor the 65.7-keVM4 transition in119Sn: Extended test of internal-conversion theory

Abstract

We have measured the K-shell internal conversion coefficient, αK , for the 65.7-keV M 4 transition in 119 Sn to be 1621(25). This result agrees well with Dirac-Fock calculations in which the effect of the K-shell atomic vacancy is accounted for, and disagrees with calculations in which the vacancy is ignored. This extends our precision tests of theory to Z = 50, the lowest Z yet measured.

Precise measurement ofαKandαTfor the 150.8-keVE3transition inNica1, Hardy2, Iacob3 et al. 2016Phys. Rev. CSelf Cite132150View full textAdd to dashboardCite

“…We take the ratio ǫ γ88 /ǫ K22.6 = 1.069(8) from our previously reported measurement [6]. The ratio ǫ γ150 /ǫ γ88.0 = 0.8707 (13) is determined from our known detector efficiency curve calculated with the CYLTRAN code [8], while ǫ K22.6 /ǫ K23.6 = 0.9849 (9) comes from a CYLTRAN calculation as well but in an energy region with higher uncertainty.…”

“…2: It includes the x-and γ-ray peaks of interest from the decay of 111m Cd, as well as a number of weak peaks from contaminant activities. In our analysis of the data, we followed the same methodology as we did with previous source measurements [1][2][3][4][5][6][7]. We first extracted areas for essentially all the x-and γ-ray peaks in the backgroundsubtracted spectrum.…”

“…The latter requires a multi-step process. Following the same procedure as the one we used in analyzing the decay of 119m Sn [6], we employ as low-energy calibration the well-known decay of 109 Cd, which emits 88-keV γ rays and silver K x rays. The latter are very close in energy to the cadmium K x rays observed in the current measurement.…”

“…In our experiments, we detect the γ rays and the K x rays in the same HPGe detector, a detector whose efficiency has been meticulously calibrated [8,18,19] to subpercent precision, originally over an energy range from 50 to 3500 keV but more recently extended [6] down to 22.6 keV, the average energy of silver K x rays. Over this whole energy region, precise measured data were combined with Monte Carlo calculations from the CYLTRAN code [20] to yield a very precise and accurate detector efficiency curve.…”

“…Over the past decade we have published a sequence of papers [1][2][3][4][5][6][7], in which we reported measurements of K-shell Internal Conversion Coefficients (ICCs) for E3 and M 4 transitions in 6 nuclei with a precision of ±2% or better. The motivation has been to test ICC theory, in particular its treatment of the K-shell vacancy left behind by the emitted electron.…”