Atomic masses of the neutron-rich isotopes , , , , and have been measured with high precision (10 ppb) using the Penning-trap mass spectrometer JYFLTRAP. Among these, the masses of four -process nuclei , , and were measured for the first time. An empirical neutron pairing gap expressed as the odd-even staggering of isotopic masses shows a strong quenching across for Sn, with a dependence that is unexplainable by the current theoretical models.
- Received 5 March 2012
© 2012 American Physical Society