New Plutonium Isotope: Pu-231

The new plutonium isotope, Pu-231, was produced by the U-233(He-3,5n)Pu-231 reaction. After chemical separation, the Pu-231 decay modes were studied using alpha-spectrometry. The isotope,Pu-231, was unequivocally identified by the alpha-decay of the chain members from its alpha- and electron-capture daughters using the alpha-alpha-correlation technique. The half-life of Pu-231 was determined to be (8.6+/-0.5) min. An cu-group with an energy of (6.72+/-0.03) MeV was assigned to Pu-231.