Open AccessCurrent saturation in free‐air ionization chambers with chopped synchrotron radiation
Author(s) -
Nariyama Nobuteru
Publication year - 2013
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049513016154
Subject(s) - ionization , atomic physics , ionization chamber , synchrotron radiation , electric field , saturation (graph theory) , ion , chopper , saturation current , synchrotron , radiation , undulator , physics , materials science , voltage , optics , mathematics , quantum mechanics , combinatorics
Saturation curves for free‐air ionization chambers with electrode gap widths of 4.2, 8.4 and 18 mm were obtained for 10 and 15 keV undulator synchrotron radiation thinned with a 230 Hz rotating‐disk chopper. Ion recombination in free‐air ionization chambers was found to be inversely proportional to the applied electric field, and an expression that satisfactorily reproduced the ion‐recombination rate is determined. A comparison of the expressions for continuous and pulsed X‐rays revealed that chopped high‐intensity X‐rays require a higher voltage to attain saturation when the product of the pulse width and electric field exceeds a value that depends on the X‐ray energy. This behaviour was observed explicitly for 10 keV X‐rays in measurements with the ionization chamber placed before and after the chopper.