On-Line Mass Measurements of Short-Lived Rubidium and Cesium Isotopes Produced in Proton Fission of Natural Uranium.

Direct on-line mass measurements are reported for short-lived neutron-rich rubidium and cesium isotopes produced in the proton fission of natural uranium. These measurements were made using a specially constructed double focusing mass spectrometer. Using a computer peak matching technique, absolute masses and mass differences were measured with a precision of 150 to 1000 microunits. Mass differences and absolute masses for rubidium isotopes with 89 less than A or equal to 95 and for cesium isotopes with 139 less than A or equal to 143 are reported. Neutron separation energies were calculated. Comparisons were made to corresponding masses calculated from beta-decay Q-value measurements.