Beta-delayed-neutron studies of $^{135,136}$Sb and $^{140}$I performed with trapped ions

Abstract

Beta-delayed-neutron (βn) spectroscopy was performed using the Beta-decay Paul Trap and an array of radiation detectors. The βn branching ratios and energy spectra for 135,136 Sb and 140 I were obtained by measuring the time of flight of recoil ions emerging from the trapped ion cloud. These nuclei are located at the edge of an isotopic region identified as having βn branching ratios that impact the r -process abundance pattern around the A∼130 peak. For 135,136 Sb and 140 I, βn branching ratios of 14.6(11)%, 17.6(28)%, and 7.6(28)% were determined, respectively. The βn energy spectra obtained for 135 Sb and 140 I are compared with results from direct neutron measurements, and the βn energy spectrum for 136 Sb has been measured for the first time.

Decay microscope for trapped neon isotopes

“…Since the BR and correlations affect the ion energy distribution differently, it makes sense to use a new, 1% determination of the BR as a prior, and deduce a more stringent BR from the recoil energy distribution itself. Such an approach was recently and successfully utilized in beta-delayed neutron spectroscopy [22,80,81]. We find that for 10 7 23 Ne simulated decay events, a two parameter fit extracts the branching ratio with a maximal relative bias of 0.3%, does not introduce significant systematic shift in a, and only slightly increases its statistical uncertainty, from 0.18% to 0.24%.…”