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Compensation for beam intensity fluctuation in determination of P ion , the ion‐recombination correction factor for ionization chambers, by the two‐voltage technique
Author(s) -
Hayakawa Yoshinori,
Loch Cinthia P.,
Tada JunIchiro,
Inada Tetsuo
Publication year - 1989
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.596343
Subject(s) - ionization chamber , atomic physics , ion , ionization , beam (structure) , ion beam , proton , intensity (physics) , laser beam quality , optics , materials science , physics , nuclear physics , laser , laser beams , quantum mechanics
We have developed a method of compensation for fluctuations in beam intensity that may occur during measurement of P ion , the ion‐recombination correction factor, by the two‐voltage technique. The method requires signals proportional to beam intensity during measurement. We used a parallel‐plate ionization chamber, whose P ion was known, and a vacuum chamber to obtain signals that were proportional to the beam intensity. Experiments were conducted using pulsed proton beam providing doses that ranged from 0.16 to 0.01 cGy/pulse. The value of P ion of a thimble ionization chamber was measured. With these measurements, the validity of the method which we proposed for pulsed beam was verified experimentally.