Study of the lowest 2+ excitations and B(E2) transition strengths in relativistic QRPA for Sn-, and Pb-isotopes

In a relativistic quasiparticle random phase approximation (RQRPA) we have calculated the excitation energies of the first 2+ excited states and reduced B(E2;0+→2+) transition rates for very neutron-defficient to neutron-rich long chain of Sn-isotopes with even mass numbers A=100-136. In RQRPA approach this is the first such attempt and a very satisfactory agreement with the available experimental data is obtained. Furthermore, we predict a substantial rise of the B(E2) values at neutron magic numbers 50 and 82, where the E2 energy also goes up, rather substantially, compared to that for the immediate neighbours. This feature is quite similar to the already experimentally known behaviour of E2 and B(E2) around 208Pb, which are also well reproduced in the present calculation.