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Re-interpretation of some experimental results of M1 penetration matrix elements in Tl203, Tl201 and Ta181

1965; Elsevier BV; Volume: 65; Issue: 3 Linguagem: Inglês

10.1016/0029-5582(65)90008-8

1873-1546

T.R. Gerholm, B.-G Petterssom, Z. Grabowski,

X-ray Spectroscopy and Fluorescence Analysis

The recent discovery of a sign error in the theory of directional correlations involving conversion electrons, leading to a sign reversal for the interference particle parameters, implies drastic changes in the interpretations of experimental results previously obtained. In the present paper we present re-interpretations of our experimental studies of certain magnetic dipole transitions in Tl203, Tl201 and Ta181. It is shown that consistent solutions exist within the framework of the corrected theory. Moreover there is now good agreement between theoretically estimated and experimentally determined values for the parameter λ for all magnetic dipole transitions investigated; λ is defined as the ratio of the penetration matrix element and the gamma-ray matrix element. The sign reversal leads to λ values entirely different from those earlier obtained. However the main conclusions drawn in our previous publications remain valid; nuclear structure dependent penetration matrix elements are found to be competitive in the case of retarded M1 transitions and affect the conversion-electron directional correlations as well as the internal conversion coefficients. For allowed M1 transitions, however, no such effects caused by the presence of penetration matrix elements can be noticed. Our results arefor the allowed 400 keV transition in Tl203, λ=+1.3±0.8,for the forbidden 279 keV transition in Tl203, λ=+7.5±1.5,for the allowed 360 keV transition in Tl201, λ=−0.5±2,for the forbidden 330 keV transition in Tl201, λ=+5±4,and for the forbidden 482 keV transition in Ta181. λ=+210±30. for the allowed 400 keV transition in Tl203, λ=+1.3±0.8, for the forbidden 279 keV transition in Tl203, λ=+7.5±1.5, for the allowed 360 keV transition in Tl201, λ=−0.5±2, for the forbidden 330 keV transition in Tl201, λ=+5±4, and for the forbidden 482 keV transition in Ta181. λ=+210±30. All of these λ values are in accordance with what is to be expected on theoretical grounds. Finally we briefly mention the importance of the knowledge of the M1 penetration matrix element for the interpretation of the recent experiment on parity violating contributions to the 482 keV transition in Ta181 suggested, for example, by the conserved vector current theory.