Experimentelle Untersuchung der Sättigungskorrektion einer PTW Roos-Ionisationskammer in gepulsten Strahlungsfeldern mit hoher Pulsdosis bei verschiedenen Pulsdauern

Research output: Contribution to journalResearch articleContributedpeer-review



In gas-filled ionization chambers as radiation detectors, the collection of the charge carriers is affected by the recombination effect. In dosimetry this effect must be accounted for by the saturation correction factor k S. The physical description of the correction factor by Boag, Hochhäuser and Balk for pulsed radiation is well established. However, this description is only accurate when the pulse length is short compared to the collection time of the ionization chamber. In this work experimental investigations of the saturation correction factor have been made for pulses of 4μs up to pulse doses of about 230 mGy, and the theory of Boag, Hochhäuser and Balk was again confirmed. For longer pulses, however, the correction factor decreases and at a pulse duration of about 200μs reaches 75% of the value valid for short pulses. This reduced influence of the ion recombination is interpreted by the reaction kinetics of ion recombination as a second-order reaction. This effect is negligible for PTW Roos chambers at clinical linear accelerators with 4μs pulse duration for pulse doses up to 120 mGy.

Translated title of the contribution
Experimental investigation of the collection efficiency of a PTW Roos ionization chamber irradiated with pulsed beams at high pulse dose with different pulse lengths


Original languageGerman
Pages (from-to)4-10
Number of pages7
JournalZeitschrift fur Medizinische Physik
Issue number1
Publication statusPublished - Mar 2011

External IDs

PubMed 21247743
ORCID /0000-0003-4261-4214/work/147143136



  • Collection efficiency, Ionization chamber, Pulsed beams, Saturation correction