L Büermann et al 2003 Phys. Med. Biol. 48 3581 doi:10.1088/0031-9155/48/21/009
L Büermann1, H-M Kramer1 and I Csete2
Show affiliationsThick walled cavity ionization chambers are used by primary standard laboratories as primary air kerma standards in 137Cs and 60Co γ-rays. Application of the cavity theory requires correction for the effects of photon attenuation and scattering in the chamber walls. For more than a decade there have been intensive discussions about the validity of wall correction factors determined by more traditional extrapolation methods versus those calculated by Monte Carlo methods. For existing primary standards the alternative methods lead to results that differ by up to 50% of the correction itself. This report presents both experimental and theoretical results which strongly support the validity of calculated wall correction factors. Moreover, it is demonstrated that, in selected cases, the application of a linear extrapolation method leads to errors in the determination of the air kerma reaching up to 13%.
29.40.Cs Gas-filled counters: ionization chambers, proportional, and avalanche counters
02.60.Ed Interpolation; curve fitting
02.70.Uu Applications of Monte Carlo methods
Accelerators, beams and electromagnetism
Issue 21 (7 November 2003)
Received 16 May 2003, in final form 18 August 2003
Published 17 October 2003
L Büermann et al 2003 Phys. Med. Biol. 48 3581
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