A new measurement of the half-life of (166m)Ho
| Autor: | Yvan Caffari, Claude Bailat, Pascal Froidevaux, Claude Wastiel, François Bochud, Gilles Triscone, Youcef Nedjadi, Niko Kivel, Ines Guenther-Leopold, Frédéric Jaquenod |
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| Rok vydání: | 2011 |
| Předmět: |
Radioisotopes
Radiation Internationality Ion exchange Isotope Chemistry Ion chromatography Analytical chemistry Half-life Equipment Design Isotope dilution Reference Standards Chromatography Ion Exchange Radiation Dosage Mass Spectrometry Equipment Failure Analysis Holmium Reference Values Mass concentration (chemistry) Nuclide Radiometry Inductively coupled plasma mass spectrometry Half-Life |
| Zdroj: | Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine. 70(9) |
| ISSN: | 1872-9800 |
| Popis: | The work presented here is a new and precise measurement of the half-life of (166m)Ho by determining the activity concentration, using an ionisation chamber calibrated for this nuclide, and measuring the number of (166m)Ho atoms using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Since the isotope (166)Er interferes with the mass spectrometric measurement, Er has to be eliminated from the (166m)Ho 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 (166m)Ho 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 (166m)Ho 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 (166m)Ho 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 (166m)Ho, 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. |
| Databáze: | OpenAIRE |
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