On the reverse micelle effect in liquid scintillation counting.
Details
Serval ID
serval:BIB_B8D66EEC8B11
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
On the reverse micelle effect in liquid scintillation counting.
Journal
Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine
ISSN
1872-9800 (Electronic)
ISSN-L
0969-8043
Publication state
Published
Issued date
07/2017
Peer-reviewed
Oui
Volume
125
Pages
94-107
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Publication Status: ppublish
Abstract
This work looks into the tracks of electrons in nanoemulsive scintillating media using the Monte Carlo Geant4-DNA code which simulates event-by-event interactions of electrons in liquid water down to the eV, without resorting to the condensed history method. It demonstrates that the average number of micelles in which electrons deposit energy is quite large, increasing with their emission energy, decreasing with micelle size, and rising with micelle concentration. The probability of an electron ending its track in a micelle is found to be rather large and micelle size-dependent below 1keV, and approximating the aqueous fraction at higher energies. Analyses of the Monte Carlo estimated energy depositions in the aqueous phase and in the scintillant tell of a micelle quenching effect, with the micelle size shaping the quenching at low energy and the micelle concentration governing it at higher energies. The micelle effect on the (3)H and (63)Ni beta spectra is discussed for a range of micelle sizes and concentrations. This paper also computes the ionisation quenching function using Birk's law whilst considering the full energy losses in the micelles bisecting the electron pathway, and not just that incurred in the primary micelle enclosing the decaying nuclide. The ionisation quenching function is then used to calculate the detection efficiencies for (3)H, (63)Ni, (54)Mn and (55)Fe. The effect of the micelle size is found to be small for beta emitters but significant for the electron capture nuclides. TDCR measurements of (63)Ni samples covering 8 aqueous fractions are analysed with and without explicit treatment of the micelle effect. Activities in the two representations agree within 0.02%. The ratios of the corresponding figures of merit are found to coincide with the scintillant fractions.
Pubmed
Create date
29/04/2017 16:13
Last modification date
20/08/2019 15:26