title: A magnet system for the suppression of conversion electrons in alpha spectrometry.
abstract: A new magnet system has been designed and constructed to reduce coincidence effects between alpha particles and conversion electrons in high-resolution alpha-particle spectrometry. By means of a magnetic field, the conversion electrons are deflected away from the PIPS(®) detector. Compared to existing magnet systems, the new system is not restricted to point sources and can accommodate source diameters up to about 30 mm. Two yokes were built, allowing for configurations with 20 mm or 36 mm distance between the magnets. The effectiveness of both configurations is demonstrated by measuring the conversion electron spectrum of a (237)Np source. The magnet system effectively rejects 93 (7)% of electrons up to 85 keV (36 mm) and 90 (9)% of electrons up to 320 keV (20 mm). It has been successfully applied in the alpha-particle spectrometry of the long-lived nuclides (236)U and (238)U, resulting in significant improvement of the accuracy of alpha emission probabilities.
authors.affiliation: European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium. Electronic address: jan.paepen@ec.europa.eu.
authors.forename: J
authors.initials: J
authors.lastname: Paepen
authors.affiliation: European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Dirican
authors.affiliation: European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Marouli
authors.affiliation: European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Pommé
authors.affiliation: European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Van Ammel
authors.affiliation: European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium.
authors.forename: H
authors.initials: H
authors.lastname: Stroh
keywords: Alpha emission probability; Alpha spectrometry; Conversion electrons; Magnet