PTB-Berichte Dosimetrie (Dos)
Comparison of the PTB and OMH Air Kerma Standards for Medium Energy x-rays
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||A comparison between the primary air kerma standards for medium-energy X-rays of the PTB and the OMH was made using a transfer ionisation chamber calibrated against both standards. The ratios of the calibration factors measured at PTB and OMH were between 1,0006 and 1,0015 for the BIPM medium energy X-ray series and between 0,9923 and 0,9983 for the ISO narrow-spectrum series. All ratios are well within the expanded uncertainties (k=2) and so the comparison results are satisfactory. However, the ratios of the calibration factors for the ISO narrow-spectrum series measured at the PTB and the OMH deviate systematically from those of the BIPM medium-energy X-ray qualities by about 0,5 % on the average. Possible causes could be beam non-uniformities which contribute to a different amount to the response of the primary standard and the transfer chamber in the measurements at both laboratories. The main properties of the X-ray beams and of the free-air standards at both laboratories are described.
||Comparison of the PTB and OMH Air Kerma Standards for Medium Energy x-rays ; (PTB-Bericht PTB-Dos-35)
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