Hindered Proton Collectivity Ins121628: Possible Magic Number Atz=16

The reduced transition probability B(E2;0gs+→21+) for S28 was obtained experimentally using Coulomb excitation at 53 MeV/nucleon. The resultant B(E2) value 181(31) e2fm4 is smaller than the expectation based on empirical B(E2) systematics. The double ratio |Mn/Mp|/(N/Z) of the 0gs+→21+ transition in S28 was determined to be 1.9(2) by evaluating the Mn value from the known B(E2) value of the mirror nucleus Mg28, showing the hindrance of proton collectivity relative to that of neutrons. These results indicate the emergence of the magic number Z=16 in the |Tz|=2 nucleus S28.Received 26 January 2012DOI:https://doi.org/10.1103/PhysRevLett.108.222501© 2012 American Physical Society