Experimental total $\beta$-decay energies of strongly neutron-rich indium isotopes are presented. The samples were produced as mass-separated fission products by using the on-line isotope separator technique. By means of a Si(Li)-detector system, $\beta$ spectra were recorded in coincidence with different $\gamma$ gates, and $Q_{\beta }$ values for isomers of ${}_{}{}^{120-129}{}_{}{}^{}\mathrm{In}$ were deduced. The atomic mass excess is derived for these nuclei, and comparisons are made with mass formula predictions. The mean uncertainty of the experimental mass excesses is 0.11 MeV. The precision of the mass formulas chosen for the comparison varies widely with rms deviations ranging from 0.21 to 1.36 MeV. For the isotopes ${}_{}{}^{124-129}{}_{}{}^{}\mathrm{In}$ the possibility of delayed-neutron emission is discussed.

RADIOACTIVITY ${}_{}{}^{120-129}{}_{}{}^{}\mathrm{In}$: Measured $\beta -\gamma$ coincidences for isomers: deduced total $\beta$-decay energies, atomic mass excesses, delayed-neutron windows; comparison with mass formulas. Mass-separated fission products, Si(Li)-detectors, Ge(Li)-detector, NaI(T1)-detectors.

• Received 19 December 1977

DOI:https://doi.org/10.1103/PhysRevC.18.462