Characteristics ofNi59andNi63

Separated stable isotopes of Ni have been used to assign a 67-kev maximum energy beta-emitter which decays with an 85-yr half-life to ${\mathrm{Ni}}^{63}$. ${\mathrm{Ni}}^{59}$ was found to decay by $K$ electron capture with a half-life of 7.5\ifmmode\times\else\texttimes\fi{}${10}^{4}$ yrs.