IJSRP, Volume 2, Issue 9, September 2012 Edition [ISSN 2250-3153]
Kawalpreet Kalra, Alpana Goel, A.K. Jain
A systematic of the signature inversion & Signature reversal phenomena in odd- odd nuclei in rare earth region are presented. It is mainly observed in high j-orbitals. These are the systematic of (h11/2p x i13/2n) orbitals. We have analyzed in total 41 cases (Experimental data have been collected from http://www.nndc.bnl.gov/chart/)in rare earths region (Z=61 to Z=75). For these configuration bands, the even spin members should lie lower in energy. However revert behaviors is observed up to certain spin called signature inversion. The point of Inversion is mentioned in the systematic shown in table. The point is shifted towards lower spin as we move towards higher isotopes. These features like signature dependence, signature inversion and signature reversal are well explained by two-quasiparticle rotor model (TQPRM). Goel et al have developed TQPRM for even-even and odd-odd nuclei. The model well explained the signature dependence and signature inversion in 152Eu, 156Tb and 160Ho of odd-odd nuclei. The signature reversal observed in 170Yb of even-even nuclei was also well explained by TQPRM model. The odd-even staggering in rotational band is due to the residual interaction. The Newby shift for the K=0 band and decoupling parameter for K=1/2 band are basically responsible for such behavior. The K=0 and K=1 bands are staggered band. This staggering is transmitted to higher K values by Coriolis coupling or by PPC (particle-particle coupling). Availability of large experimental data of odd-odd nuclei helps to do the further work in this region. We are in process not only to explain this feature but also shifting in the point of inversion as mass number increases. In future we will present systematic by TQPRM calculations.