Mainz 2026 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 1: Resonance Ionization Spectroscopy / Mass Spectrometry

MS 1.2: Vortrag

Montag, 2. März 2026, 12:00–12:15, N 6

Thermal Neutron-Induced Cross-Sections of ²⁵⁴Es and ²⁵⁵Es — •Melanie P. Feucht¹, Thomas E. Albrecht², Sebastian Berndt¹, Christoph E. Düllmann^1,3,4, Julie G. Ezold⁵, Raphael Hasse¹, Ulli Köster⁶, Andrea T. Loria Basto^1,4, Christoph Mokry^1,4, Kristian Myhre⁵, Thorben Niemeyer¹, Sebastian Raeder^3,4, Dennis Renisch^1,4, Jörg Runke^1,3, Samantha K. Schrell⁵, and Klaus Wendt¹ — ¹JGU Mainz, Germany — ²CSM Golden, CO, USA — ³GSI Darmstadt, Germany — ⁴HIM Mainz, Germany — ⁵ORNL Oak Ridge, TN, USA — ⁶ILL Grenoble, France

Knowledge of neutron-induced cross-sections is essential for predicting the production of heavy isotopes via neutron capture. Previous studies show that the experimentally observed yield of ²⁵⁵Es produced from ²⁵⁴Es in nuclear reactors deviates significantly from theoretical expectations. We have studied the burnup (which is the sum of the neutron capture (n,γ) and the neutron induced fission (n,f)-processes) of ²⁵⁴Es and ²⁵⁵Es. For this we investigated the transmutation of ²⁵⁴Es to ²⁵⁵Es by irradiations at different neutron fluence in order to deduce the relevant cross-sections. The study made use of ²⁵⁴Es samples irradiated at the high-flux reactor at ILL. The isotopic composition of all samples was characterized before and after irradiation, and the ²⁵⁴Es/²⁵⁵Es ratios were determined using alpha spectrometry and resonance ionization mass spectrometry. The results provide an enhanced and more precise basis for predicting the yields of the heaviest reactor-producible elements, einsteinium and fermium.

Keywords: Burnup; Neutron capture; Isotopic Ratio; RIMS