title: Time optimization of (90)Sr measurements: Sequential measurement of multiple samples during ingrowth of (90)Y.
abstract: The aim of this paper is to contribute to a more rapid determination of a series of samples containing (90)Sr by making the Cherenkov measurement of the daughter nuclide (90)Y more time efficient. There are many instances when an optimization of the measurement method might be favorable, such as; situations requiring rapid results in order to make urgent decisions or, on the other hand, to maximize the throughput of samples in a limited available time span. In order to minimize the total analysis time, a mathematical model was developed which calculates the time of ingrowth as well as individual measurement times for n samples in a series. This work is focused on the measurement of (90)Y during ingrowth, after an initial chemical separation of strontium, in which it is assumed that no other radioactive strontium isotopes are present. By using a fixed minimum detectable activity (MDA) and iterating the measurement time for each consecutive sample the total analysis time will be less, compared to using the same measurement time for all samples. It was found that by optimization, the total analysis time for 10 samples can be decreased greatly, from 21h to 6.5h, when assuming a MDA of 1Bq/L and at a background count rate of approximately 0.8cpm.
authors.affiliation: Swedish Defence Research Agency (FOI), CBRN Defence and Security, Cementvägen 20, 901 82 Umeå, Sweden. Electronic address: stina.holmgren@foi.se.
authors.forename: Stina
authors.initials: S
authors.lastname: Holmgren
authors.affiliation: Swedish Defence Research Agency (FOI), CBRN Defence and Security, Cementvägen 20, 901 82 Umeå, Sweden.
authors.forename: Annika
authors.initials: A
authors.lastname: Tovedal
authors.affiliation: Swedish Defence Research Agency (FOI), CBRN Defence and Security, Cementvägen 20, 901 82 Umeå, Sweden.
authors.forename: Oscar
authors.initials: O
authors.lastname: Björnham
authors.affiliation: Swedish Defence Research Agency (FOI), CBRN Defence and Security, Cementvägen 20, 901 82 Umeå, Sweden; Chalmers University of Technology, Department of Chemistry and Chemical Engineering, Nuclear Chemistry, Kemivägen 4, 412 58 Göteborg, Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Ramebäck
keywords: (90)Sr; (90)Y; Multiple samples; Optimization; Sequential measurement