DELAYED NEUTRON ENERGY-SPECTRA OF BR-87, BR-88, BR-89, BR-90, I-137, I-138, I-139, AND TE-136

Measurement of the energy spectra of delayed neutrons for the isotope- separated, fission product precursors Br-87, Br-88, Br-89, Br-90, I-13 7, I-138, I-139, and Te-136 are reported for an energy range up to 121 3 keV and with lower cutoff energies of 11.1, 11.1, 29.9, 48.9, 14.2, 23.3, 29.9, and 48.9 keV respectively. These data were obtained at the TRISTAN Isotope Separation On-Line facility using H-2 and CH4 gas-fil led proportional counters. The data for each of the bromine, iodine, a nd tellurium isotopes show good qualitative agreement with the publish ed He-3 ionization chamber delta at energies above similar to 200 keV. In addition, they provide definitive spectral information down to the ir respective cut-off energies.