Conversion electron spectroscopy of the 59.54 keV transition in 241Am alpha decay

S Pommé; J Paepen; M Marouli

doi:10.1016/j.apradiso.2019.108848

Conversion electron spectroscopy of the 59.54 keV transition in ²⁴¹Am alpha decay

Appl Radiat Isot. 2019 Nov:153:108848. doi: 10.1016/j.apradiso.2019.108848. Epub 2019 Aug 9.

Authors

S Pommé¹, J Paepen², M Marouli²

Affiliations

¹ European Commission, Joint Research Centre (JRC), Geel, Belgium. Electronic address: stefaan.pomme@ec.europa.eu.
² European Commission, Joint Research Centre (JRC), Geel, Belgium.

PMID: 31442878
DOI: 10.1016/j.apradiso.2019.108848

Abstract

A windowless Peltier-cooled silicon drift detector (SDD) was used to measure internal conversion electron (ICE) spectra of thin ²⁴¹Am sources. The ICE peaks associated with the 59.54 keV gamma transition in ²³⁷Np were deconvoluted and relative ICE intensities were derived from the fitted peak areas. Corrections were made for energy dependence of the full-energy-peak counting efficiency, based on Monte Carlo simulations. As expected for this anomalous E1 transition, a significant discrepancy was found with the theoretical internal conversion coefficient (ICC) values calculated from the BrIcc database. Penetration effects are known to cause such anomalies in highly retarded transitions. The measured ICE intensities are in good agreement with a specific combination of literature data obtained with magnetic spectrometers.

Keywords: (241)Am; Electron emission probability; Internal conversion; Nuclear forensics; Plutonium.