A STUDY OF CAVITY ION CHAMBERS FOR USE WITH 2 mV X-RAWS: EQUILIBRIUM WALL THICKNESS: WALL-ABSORPTION CORRECTION
The difficulties associated with the determination of the equilibrium wall thickness and the associated wallabsorption correction in a cavity ion chamber to be used with radiation of a particular quantum energy are discussed in some detail. It does not appear passible to devise any experiment to measure directly the gamma ray or x ray absorption in the wall of the chamber. An analytical study has been made of total ionization versus wallthickness curves from which the required wall-absorption correction is derived. It appears that electronic equilibrium is not fully achieved in the N.P.L. graphite cavity chambers; but since the wall-absorption correction at present applied is too large, partial compensation for lack of electronic equilibrium is fortuitously achieved. As a by-product of this analysis, a new method of deriving the relationship between total ionization and atomic number of wall material has been developed for a single chamber. It is suggested that this merits further experimental study with monoenergetic sources. (auth)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-13-019159
- OSTI ID:
- 4212847
- Journal Information:
- Phys. in Med. Biol., Journal Name: Phys. in Med. Biol. Vol. Vol: 3
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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