Isomeric state at 945.3 keV in 237Np

A new isomeric state in 237Np has been discovered at an excitation energy of (945.3±0.2) keV with T1/2=(711±40) ns. Six gamma-ray lines have been measured depopulating the isomeric state to known levels in 237Np. The comparison of the measured absolute gamma-ray transition probabilities with empirical values yields as most probable spin I and K assignment I=K=13/2 for this isomeric state. It is most likely a 1-proton-2-neutron quasiparticle state 13/2- {π5/2+[642]+ν7/2-[743]+ν1/2+[631]}. However, a one-quasiparticle 11/2-[505] configuration for the isomer cannot be excluded. (orig.)