Half-life Measurement Using Implant-\((\beta -\Gamma )\) Time Correlations in the Region of Neutron-rich Lanthanides

Neutron-rich lanthanides were produced via in-flight fission of a U-238 primary beam at the RIBF, RIKEN Nishina Center to measure half-lives (T-1/2) and beta-delayed neutron emission probabilities (P-n) in order to constrain r-process abundance calculations. Pm159-166, Sm161-168, Eu165-170, and Gd167-172 ions were implanted in the Advanced Implantation Detector Array (AIDA), and beta-delayed neutrons and gamma-rays were detected by the surrounding detector array (BRIKEN). For the validation of T-1/2 values derived from implantation-beta (i-beta) time correlations, gamma-spectroscopic methods were used as well. The experimental results of the beta-delayed gamma-spectroscopy of Pm-162 are presented here as an example. A half-life value from gamma-decay curves was derived with a comparable uncertainty to the result from the i-beta method, and a mean value well within the 1 sigma range.