Abstract
Delayed-neutron emission from mass separated heavy fission products has been studied using a sensitive neutron counter. Twelve new delayed-neutron precursors have been found, namely Ag122, Ag123, In127, Cd128 (or Inm128), In128, In129 (two isomers), In130, In131, In132, Sn133, and Sb136. The half-life determination for 11 other precursors has been improved.