G. Rudstam

Delayed neutron emission probabilities of gallium, bromine, rubidium, indium, antimony, iodine, and cesium precursors

The delayed neutron emission probability(Pn) has been measured for79-83Ga,87-89Br,92-96Rb127-132In134,135Sb137-139I and141 -145Cs, by means of sources produced at the OSIRIS isotope separator at Studsvik. The half-life determinations of127, 129, 132In have been improved.

Delayed neutron emission probabilities of the precursors89,90,91Br and139,140,141I

The delayed neutron emission probabilities of89,90,91Br and139,140,141I have been measured. The ions AlBr+ and AlI+ are formed in the OSIRIS integrated target-ion source giving improved conditions for study of the most neutron-rich isotopes of iodine and bromine. The half-life determinations of90Br,139I and141I have been improved.

Decay schemes and total decay energies of89Br and90Br

Spectroscopical investigations of89Br and90Br have been performed, utilizing the formation of the molecular ion AlBr+ in the ion-source of an isotope separator on-line a reactor. Detailed level schemes have been constructed for89Kr and90Kr, and theβ-strength function of89Br and90Br below the neutron binding energy is presented. The total decay energy of89,90Br, as well as of89Kr, have been measured by means ofβγ-coincidences, and the population of excited states in89Kr via90Br delayed neutrons has been deduced.

Total β-decay energies and masses of85–89Br

Experimentalβ-decay energies of neutron-rich bromine 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,β-spectra were recorded in coincidence with differentγ-gates, and {ie173-01}-values for85–89Br were deduced. The atomic mass excess is derived for these nuclei, and comparisons are made with mass formula predictions. The possibility of delayed-neutron emission is discussed in conjunction with information from the shape of the delayed-neutron spectra.

Totalβ-decay energies and masses of80,81Ga and79,81,82Ge

Experimental totalβ-decay energies for short-lived isotopes of gallium and germanium are presented. The sources were produced as mass-separated fission products at the OSIRIS on-line separator at Studsvik. By applyingβ-γ-coincidence methodsQα-values were determined for80,81Ga and79,81,82Ge. For these nuclei on or close to the shellN =50 and in the vicinity of ther-process “seed”, the atomic mass excess is derived and compared with predictions from mass formulae.