Review Of LogftValues In β Decay

Abstract

The logftvalues for all β decay branches (β−, β+, ϵ) have been retrieved from the Evaluated Nuclear Structure Data File (ENSDF–August 1997 version) and reviewed. Only those cases where the β transition occurs between levels of firmly assigned Jπ values (consistent with strong rules for Jπ assignments are given in policies of Nuclear Data Sheets), have been considered in this review. Weak β branches (<=1%) in complex decay schemes have been omitted. Some new values from recent literature have also been added. Out of a total of about 20,000 β transitions reported in ENSDF, about 3,900 are presented in this review. A similar complete review was last done by 63GlZZ where about 900 transitions were considered, which included weak transitions as well as those between levels of tentative Jπ assignments. Theftvalues in β decay, spanning about 21 orders of magnitude, have been classified into allowed and forbidden categories according to the classification scheme of Konopinski (43Ko08). Centroid, width, minimum and maximum values for each category have been calculated here. Lower limits for first and second forbidden transitions in the present review have been compared to those given in the review by Raman and Gove (73Ra10) which contained about 160 selected logftvalues.