A new measurement of the half-life of 166mHo

Nedjadi, Youcef (Institute of Radiation Physics, University Hospital and University of Lausanne, Lausanne, Switzerland) ; Bailat, Claude (Institute of Radiation Physics, University Hospital and University of Lausanne, Lausanne, Switzerland) ; Caffari, Y. (Institute of Radiation Physics, University Hospital and University of Lausanne, Lausanne, Switzerland) ; Froidevaux, Pascal (Institute of Radiation Physics, University Hospital and University of Lausanne, Lausanne, Switzerland) ; Wastiel, Claude (Institute of Radiation Physics, University Hospital and University of Lausanne, Lausanne, Switzerland) ; Kivel, Niko (Paul Scherrer Institut, Villigen, Switzerland) ; Guenther-Leopold, Ines (Paul Scherrer Institut, Villigen, Switzerland) ; Triscone, Gilles (School of Engineering, Architecture and Landscape (hepia), HES-SO // University of Applied Sciences Western Switzerland) ; Jaquenod, Frédéric (School of Engineering, Architecture and Landscape (hepia), HES-SO // University of Applied Sciences Western Switzerland) ; Bochud, François (Institute of Radiation Physics, University Hospital and University of Lausanne, Lausanne, Switzerland)

The work presented here is a new and precise measurement of the half-life of 166mHo by determining the activity concentration, using an ionisation chamber calibrated for this nuclide, and measuring the number of 166mHo atoms using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Since the isotope 166Er interferes with the mass spectrometric measurement, Er has to be eliminated from the 166mHo radioactive solution. The elimination was achieved using ion-exchange chromatography with the cation exchange resin Dowex AG 50W-X8 and 2-Hydroxybutanoic acid as the mobile phase. After a first transit through the chromatographic column, the purified 166mHo eluate was spiked with natural Er to get a resulting Er isotopic composition close to that of natural Er at better than 99.5%, and then it underwent two further separations to eliminate the Er. The activity concentration of this Er-free radioactive 166mHo solution was measured in our reference ionisation chamber calibrated for this nuclide by means of the 4πβ(PC)-γ and 4πβ(PS)-4πγ coincidence techniques and integral counting with a well-type NaI(Tl) detector and Monte Carlo efficiencies. An aliquot of this standardized solution was sent to the Paul Scherrer Institute (PSI) for mass concentration determination using an isotope dilution MC-ICP-MS approach. The mass concentration of 166mHo in this solution was determined with 0.25% relative standard uncertainty. This value was corroborated by two other independent measurements. The new half-life of 166mHo, 1132.6(39) years (k=1), is compatible with the value determined in 1965, but is 5.6% shorter and about 43 times more precise.


Keywords:
Article Type:
scientifique
Faculty:
Ingénierie et Architecture
School:
HEPIA - Genève
Institute:
inSTI - Institut des Sciences et Technologies industrielles
Date:
2012-03
Pagination:
7 p.
Published in:
Applied Radiation and Isotopes
Numeration (vol. no.):
2012, vol. 70, pp. 1990-1996
DOI:
ISSN:
0969-8043
Appears in Collection:

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 Record created 2020-03-27, last modified 2020-05-08

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