Experimental mass excess of 49K and 50K.

Abstract

The beta decay energy ${Q}_{\ensuremath{\beta}}$ of the delayed neutron emitters $^{49}$,50K produced by fragmentation of a uranium target with a 600 MeV proton beam has been determined. Energies of the beta transitions to well-located neutron emitting levels in the daughter nuclei have been measured by means of a scintillation telescope in coincidence with a large solid angle neutron time of flight spectrometer. The $^{49}\mathrm{K}$ and $^{50}\mathrm{K}$ inferred mass excesses, -30.33\ifmmode\pm\else\textpm\fi{}0.07 and -25.5\ifmmode\pm\else\textpm\fi{}0.3 MeV, respectively, are compared with mass predictions.