Résumé du preprint Irfu-13-98

Irfu-13-98
Coulomb excitation of 104Sn and the strength of the 100Sn shell closure
G. Guastalla et al. (A. Obertelli)
A measurement of the reduced transition probability for the excitation of the ground state to the first 2+ state in 104Sn has been performed using relativistic Coulomb excitation at GSI. 104Sn is the lightest isotope in the Sn chain for which this quantity has been measured. It is also the heaviest neutron-deficient Sn isotope for which a large scale shell model calculation can be performed without significant truncation. The result is therefore a key point in the discussion of the evolution of nuclear structure in the proximity of the doubly magic nucleus 100Sn. The value B(E2; 0+ ! 2+) = 0:10(4) e2b2 is significantly lower than earlier results for 106Sn and heavier isotopes. The result is well reproduced by shell model predictions and therefore indicates a robust N = Z =50 shell closure.