Showing 130 results for Author: Dan W. Stracener
Aug, 2026
Journal
Actinium-225 (t1/2 = 9.92 days) is an important radioisotope for targeted alpha therapy applications. The limited supply obtained through the decay of thorium-229 has motivated accelerator-based production routes, including irradiation of thorium targets. Irradiated targets can produce useful quantities of actinium-225, but the product requires final purification from chem…
Jan, 2026
Journal
High-lying Rydberg and autoionizing (AI) states of thorium (Th) have been studied via resonance laser ionization spectroscopy at both TRIUMF Canada’s particle accelerator center and Oak Ridge National Lab (ORNL). Multiple Rydberg series converging to the ionization potential (IP) were observed via different stepwise laser excitation schemes and were assigned to be the 6d27…
Nov, 2025
Journal
A segmented-scintillator-based implantation detector was developed to study the energy distribution of β-delayed neutrons emitted from exotic isotopes. The detector comprises a 34 × 34 YSO scintillator coupled to an 8 × 8 anode Position-Sensitive Photo-Multiplier Tube (PSPMT) via a tapered light guide. The detector was used at RIBF, RIKEN for time-of-flight-based neutron s…
Oct, 2025
Journal
The 𝛽 decay of 125𝑚,125Ag into levels in 125Cd was investigated at the Holifield Radioactive Ion Beam Facility (HRIBF). Uranium-238 targets were bombarded with 50-MeV protons with an intensity of 15𝜇A, and the induced fission products were mass separated and deposited on a moving tape in the center of the VANDLE array consisting of 𝛾 detectors and plastic scintillators. A…
May, 2025
Journal
Neutron emission probabilities and half-lives of 37 β-delayed neutron emitters from 75Ni to 92Br were measured at the RIKEN Nishina Center in Japan, including 11 one-neutron and 13 two-neutron emission probabilities and six half-lives for the first time that supersede theoretical estimates. These nuclei lie in the path of the weak r process occurring in neutrino-driven win…
Apr, 2025
Journal
The β decays of 87Br, 88Br, and 87Kr were measured with the Modular Total Absorption Spectrometer (MTAS) at Oak Ridge National Laboratory’s Holifield Radioactive Ion Beam Facility (HRIBF). Both bromine isotopes are β-delayed neutron emitters that have large cumulative fission yields and were identified as top-priority cases for total absorption study by the Nuclear Energy…
Apr, 2025
Journal
SPES (Selective Production of Exotic Species) is the Radioactive Ion Beam (RIB) facility that is currently in the installation phase at the Istituto Nazionale di Fisica Nucleare in the Laboratori Nazionali di Legnaro (LNL-INFN). The main purpose of the facility is to deliver neutron-rich radioactive beams with a range of mass between 60 and 160 amu produced as fission prod…
Feb, 2024
Journal
β-delayed γ-neutron spectroscopy has been performed on the decay of A=84 to 87 gallium isotopes at the RI-beam Factory at the RIKEN Nishina Center using a high-efficiency array of 3He neutron counters (BRIKEN). β−2n−γ events were measured in the decays of all of the four isotopes for the first time, which is direct evidence for populating the excited states of two-neutron…