Identification and halflife measurement of 100sn and neighbouring nuclei

We report the first observation of the doubly-magic nucleus 100Sn. This isotope was produced by nuclear fragmentation of l21Xe projectiles at 1095 A MeV using the heavy-ion synchrotron SIS at GSI, Darmstadt. The projectile fragments were separated in flight with the projectile fragment separator FRS and identified by measuring event by event magnetic rigid-ity, the time of flight and the energy deposition. The analysis of the decay events following the implantation of the fragments into a stack of Si detec-tors revealed for the first time the halflives of the isotopes 100Sn, 104Sb, 105Sb.