β -delayed neutron emission studies of I137,138 and Cs

Abstract

A detailed study of the β-delayed neutron emission properties of 137,138 I and 144,145 Cs has been performed by confining ions in the Beta-decay Paul Trap. The daughter ions following β decay emerge from the trapped-ion cloud with negligible scattering allowing reconstruction of the recoilion energy from the time-of-flight. From this information, the neutron-emission branching ratios and neutron-energy spectra were deduced. The results for the 137 I and 144,145 Cs decays are in agreement with previous results performed using direct neutron-detection techniques. In the case of 138 I, 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.

Horizons: nuclear astrophysics in the 2020s and beyond

“…The recently recognized diversity of astrophysical neutron capture processes, including the s-process, the i-process, the r-process, and the n-process, further underscores the need to address the challenge of obtaining neutron capture rates for unstable nuclei. While direct measurements of neutron capture on very short-lived nuclides are presently not feasible, multiple indirect experimental techniques and advances in nuclear-reaction theory make it possible to obtain constraints for important reaction rates (figure 3): β-delayed neutron emission [244,245], the β-Oslo [246,247] and inverse-Oslo [248] methods, transfer reactions [249][250][251], the surrogate reaction method [252][253][254], the Trojan Horse Method [114], and Coulomb breakup [255][256][257] offer pathways to study neutron-capture reactions on short-lived isotopes. In addition, measurements of evaporation spectra at stable-beam facilities [258] provide complementary information for nuclei just off stability, e.g., for those relevant to i-process nucleosynthesis.…”

Horizons: Nuclear Astrophysics in the 2020s and Beyond

“…While direct measurements of neutron capture on very shortlived nuclides are presently not feasible, multiple indirect experimental techniques and advances in nuclear-reaction theory make it possible to obtain constraints for important reaction rates (Fig. 3): β-delayed neutron emission [244,245], the β-Oslo [246,247] and inverse-Oslo [248] methods, transfer reactions [249,250,251], the surrogate reaction method [252,253,254], and the Trojan Horse Method [114] offer pathways to study neutron-capture reactions on short-lived isotopes. In addition, measurements of evaporation spectra at stable-beam facilities [255] provide complementary information for nuclei just off stability, e.g., for those relevant to i-process nucleosynthesis.…”