Photon W-value of dry air determined using a cryogenic radiometer combined with a multi-electrode ion chamber for soft X-rays

The photon W-value of dry air in the energy range of 2.2–3.9 keV has been measured with relative expanded uncertainty of 0.84% (coverage factor k = 2 ). Monochromatized synchrotron radiation was used for both measurements of the radiant power by means of a cryogenic radiometer and of photoion curren...

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Bibliographic Details
Published in:Radiation physics and chemistry (Oxford, England : 1993) England : 1993), 2010-04, Vol.79 (4), p.397-404
Main Authors: Kato, M., Suzuki, I.H., Nohtomi, A., Morishita, Y., Kurosawa, T., Saito, N.
Format: Article
Language:English
Subjects:
Air
Attenuation coefficients
Drying
Ion chambers
Mass attenuation coefficient
Mathematical models
Photons
Radiometer
Radiometers
Soft X-ray
Soft x-rays
Synchrotron radiation
W-value
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Summary:The photon W-value of dry air in the energy range of 2.2–3.9 keV has been measured with relative expanded uncertainty of 0.84% (coverage factor k = 2 ). Monochromatized synchrotron radiation was used for both measurements of the radiant power by means of a cryogenic radiometer and of photoion currents for ion-pair production by means of a multi-electrode ion chamber technique. The evaluated dependence of the photon W-value for dry air is consistent with the previously reported data for electrons and seems to show a small change at the Ar 1s ionization threshold. These findings were well reproduced with a model calculation using atomic photoionization data. Mass attenuation coefficients for air have been observed in the present soft X-ray region with a small energy step, which are close to data previously reported.
ISSN:0969-806X
1879-0895
DOI:10.1016/j.radphyschem.2009.12.009