beta-delayed neutron emission studies of I-137,I-138 and Cs-144,Cs-145 performed with trapped ions

A detailed study of the beta-delayed neutron emission properties of I-137,I-138 and Cs-144,Cs-145 has been performed by confining ions in the Beta-decay Paul Trap. The daughter ions following beta decay emerge from the trapped-ion cloud with negligible scattering allowing reconstruction of the recoil-ion energy from the time of flight. From this information, the neutron-emission branching ratios and neutron-energy spectra were deduced. The results for the I-137 and Cs-144,Cs-145 decays are in agreement with previous results performed using direct neutron-detection techniques. In the case of I-138, a branching ratio of 6.18(50)% is obtained, yielding a value consistent with the more recent results, which are a factor of two larger than measurements made prior to 1978.