Development and Characterization of a New Cylindrical Ionization Chamber for Dosimetry of $^{60}{\rm Co}$ Beams

A cavity ionization chamber, made of PVC coated with graphite, was developed and tested to verify its applicability as a reference dosimeter for
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Co beams. In order to characterize this new ionization chamber, several tests were made, following international recommendations, as saturation, ion collection efficiency, polarity effect, short- and medium-term stabilities, linearity of response, angular dependence and leakage current. All results obtained were within those recommended internationally, showing that this prototype may be used as a dosimetric standard system at the Calibration Laboratory of IPEN.