Eur. Phys. J. A (2016) 52: 5
https://doi.org/10.1140/epja/i2016-16005-6

Regular Article - Theoretical Physics

First-forbidden -decay rates, energy rates of -delayed neutrons and probability of -delayed neutron emissions for neutron-rich nickel isotopes

¹ Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Swabi, Topi 23640, Khyber Pakhtunkhwa, Pakistan
² Department of Physics, Karabük University, 78050, Karabük, Turkey

^* e-mail: jameel@giki.edu.pk

Received: 11 July 2015
Accepted: 10 December 2015
Published online: 14 January 2016

Abstract

First-forbidden (FF) transitions can play an important role in decreasing the calculated half-lives specially in environments where allowed Gamow-Teller (GT) transitions are unfavored. Of special mention is the case of neutron-rich nuclei where, due to phase-space amplification, FF transitions are much favored. We calculate the allowed GT transitions in various pn-QRPA models for even-even neutron-rich isotopes of nickel. Here we also study the effect of deformation on the calculated GT strengths. The FF transitions for even-even neutron-rich isotopes of nickel are calculated assuming the nuclei to be spherical. Later we take into account deformation of nuclei and calculate GT + unique FF transitions, stellar -decay rates, energy rate of -delayed neutrons and probability of -delayed neutron emissions. The calculated half-lives are in excellent agreement with measured ones and might contribute in speeding-up of the r-matter flow.