Enhanced proton-neutron interactions occur in heavy nuclei along a trajectory of approximately equal numbers of valence protons and neutrons. This is also closely aligned with the trajectory of the saturation of quadrupole deformation. The origin of these enhanced p-n interactions is discussed in terms of spatial overlaps of proton and neutron wave functions that are orbit-dependent. It is suggested for the first time that nuclear collectivity is driven by synchronized filling of protons and neutrons with orbitals having parallel spins, identical orbital and total angular momenta projections, belonging to adjacent major shells and differing by one quantum of excitation along the z axis. These results may lead to a new approach to symmetry-based theoretical calculations for heavy nuclei

Abstract. We present the results of a novel Mössbauer experiment in a rotating system, implemented recently in Istanbul University, which yields the coefficient k=0.690.02 within the frame of the expression for the relative energy shift between emission and absorption lines E/E=ku 2 /c 2 . This result turned out to be in a quantitative agreement with an experiment achieved earlier on the subject matter (A.L. Kholmetskii et al. 2009 Phys. Scr. 79 065007), and once again strongly pointed to the inequality k>0.5, revealed originally in (A.L. Kholmetskii et al. 2008 Phys. Scr. 77, 035302 (2008) via the re-analysis of Kündig's experiment (W. Kündig. Phys. Rev. 129, 2371). A possible explanation of the deviation of the coefficient k from the relativistic prediction k=0.5 is discussed.

We have studied the f decay of the Tz = -1 , f y2 shell nuclei 54Ni, 50Fe, 46Cr, and 42Ti produced in fragmentation reactions. The proton separation energies in the daughter T. = 0 nuclei are relatively large («4-5 MeV) so studies of the y rays are essential. The experiments were performed at GSI as part of the Stopped-beam campaign with the RISING setup consisting of 15 Euroball Cluster Ge detectors. From the newly obtained high precision /1-decay half-lives, excitation energies, and f branching ratios, we were able to extract Fermi and Gamow-Teller transition strengths in these f) decays. With these improved results it was possible to compare in detail the Gamow-Teller (GT) transition strengths observed in beta decay including a sensitivity limit with the strengths of the Tz = +1 to Tz = 0 transitions derived from high resolution (3He,f) reactions on the mirror target nuclei at RCNP, Osaka. The accumulated B(GT) strength obtained from both experiments looks very similar although the charge exchange reaction provides information on a broader energy range. Using the "merged analysis" one can obtain a full picture of the £(GT) over the full Qp range. Looking at the individual transitions some differences are observed, especially for the weak transitions. Their possible origins are discussed.