| Autor: |
Woods, D.H., Bowles, N.E., Jerome, S.M., Lavison, P. de, Lineham, S., Makepeace, J.L., Woodman, A.P., Woods, M.J. |
| Zdroj: |
Applied Radiation and Isotopes: Including Data, Instrumentation, and Methods for Use in Agriculture, Industry, and Medicine; 2000, Vol. 52 Issue: 3 p381-385, 5p |
| Abstrakt: |
The standardisation of 210 Pb is complicated by the presence of the daughters, 210 Bi and 210 Po. In addition, the low energies of the beta emissions from 210 Pb make it difficult to obtain high detection efficiencies in an atmospheric proportional counter and hence produce the need for large extrapolations with consequential large uncertainties when extrapolating to unit efficiency with the conventional 4π(PC)-γ-coincidence technique. In order to produce a reliable standardisation, it is necessary to remove the daughter products. A solution of 210 Pb was therefore chemically separated from its daughters and then standardised using the conventional 4π(LS)-γ-coincidence technique. The low energy (46 keV) and low emission probability (4%) of the associated photon emissions effectively rules out the possibility of using ionisation chambers as secondary standard transfer instruments for this nuclide. A germanium spectrometer therefore was calibrated for this purpose using 241 Am as a normalising agent. The results of this work are presented together with an analysis of the standardisation uncertainties that can be achieved in practice. |
| Databáze: |
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