Tuesday, September 1, 2009

Disappearance of the N=14 shell

Using the MoNA detector an excited state of 22N unbound with respect to neutron emission was observed in a stripping reaction from a 85 MeV/nucleon 26F beam at the NSCL. The observed decay energy of 650(50) keV places the level, which is interpreted to be the first 3- state, at an excitation energy of 1.93(22) MeV. This new measurement combined with previous determinations of the bound state in 22N indicates a reduction in the N=14 shell gap compared with less neutron-rich isotopes. M. J. Strongman, et. al., Phys. Rev C 80, 021302(R) (2009)

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