Effect of non-local barrier and relative intensities of alpha-spectra in rare-earth nuclei

Abstract

2014 La méthode pour calculer les taux de décroissance 03B1 en prenant pour barrière le potentiel coulombien et un potentiel non local alpha-noyau avec terme d'échange est appliquée aux isotopes 149,151Tb, 149Tbm et 153Dy. Ce calcul montre que l'intensité relative mesurée, 03BB1/03BB0, peut en grande partie être reproduite par les rapports des pénétrabilités, ce qui permet de calculer les largeurs partielles 03B421. Des calculs similaires utilisant un potentiel alpha-noyau statique donnent 03B42l ~ 03B420, en contradiction avec l'analyse des amplitudes spectroscopiques qui donne 03B421 > 03B420. Il est remarquable que cette méthode corrige dans une large mesure ce désaccord, donnant un rapport 03B421/03B420 de l'ordre de 1,1 à 2,2. On peut en conclure que les valeurs de 03B421 obtenues avec un potentiel statique sont trop faibles et que celles données dans le tableau II peuvent être utilisées, dans des limites raisonnables, pour des études de structure nucléaire. Abstract. 2014 The method of calculating alpha-decay intensities taking the barrier to be the usual Coulomb potential superposed by a non-local alpha-nucleus potential with exchange term is applied here to the fine structures of the rare-earth isotopes 149,151Tb, 149Tbm and 153 Dy. The present calculations consistently show that the measured relative intensities, 03BB1/03BB0, are largely accounted for in terms of the non-local penetrability ratios and hence the values of the reduced widths 03B421, are calculated. Similar calculations using static alpha-nucleus potential give 03B421 ~ 03B420 which is contrary to the finding, viz., 03B421 > 03B420 obtained from other sources, for example, from the studies of alpha-spectroscopic amplitudes. It is remarkable that the present method largely makes up this discrepancy giving 03B421/03B420 in the range of 1.1 to 2.2, and it is concluded that the values of 03B421 from static potential are too low and those given in table II are within reasonable limits for use in studying nuclear structures.

Assessment of nonlocal nuclear potentials in α decay

“…Before closing the discussions, some comments about one of the earliest investigations of nonlocalities in alpha decay are in order here. In a series of works [31][32][33][34], M. L. Chaudhury studied the effects of nonlocalities in alpha decay of different nuclei. Using an integro-differential equation similar to that of Frahn and Lemmer [35], in Ref.…”

“…[31] was extended to several even-even nuclei and the author once again found a large increase (∼ 50 %) [32] in the penetration factors due to nonlocality. The author further studied the effects of nonlocality in deformed and rare earth nuclei [33,34] with the inclusion of an exchange term in the nonlocal kernel. Though the calculation in Ref.…”