Seminarium Fizyki Jądra Atomowego

Numerous experimental and theoretical studies are currently focused on nuclear shell structure far from the line of stability. In particular, the evolution of nuclear properties, for example, the reduced transition probabilities across the Z=50 chain of tin isotopes, has been examined in detail. This constitutes the longest shell-to-shell chain of semi magic nuclei investigated in nuclear structure to date. Radioactive ion beams yield new experimental results close to the doubly magic 100Sn and 132Sn, but very accurate data on the stable mid shell nuclei are also of great relevance for our understanding of nuclear structure. In semi magic nuclei, such as the tin isotopes, the seniority scheme provides a very valuable tool for describing the low energy spectra. In tellurium nuclei with two protons outside the major shell, the partial level schemes are dominated by the 1g7/2 orbit leading to 6+ isomers in the vicinity of N = 82 shell closure. For the midshell nuclei 120,122,124Te one observes the expected transition to vibrational-like structure with equal energy spacings between the phonon states. This observation is in contrast to the measured quadrupole moments Q2+ for the doubly even Te isotopes. These quadrupole moments can reach 60% of the one predicted by the symmetric rigid rotor. In view of the present ambiguities in the B(E2) systematics in nuclei around Z=50, several Coulex experiments were performed in last few years. During this talk I shall present the interesting outcomes and results obtained from these various measurements on stable Te and Sn isotopes.