Oxalic acid dosimeter

A review is given on the experiences with the oxalic acid dosimeter. The system was first suggested by Draganic, who has carried out extensive investigations on the dosimetric properties. Further experiments have been carried out at various laboratories—e.g., in the United States, Japan, and Denmark. Although the system suffers from some systematic weaknesses, it can be applied successfully, when properly calibrated under the conditions where it is to be used. The present report describes its application for 60Co and high dose-rate electron dosimetry. 

Tphe oxalic-acid dosimeter has a history comparable to that of the ceric-sulfate dosimeter. Much work has been carried out, promising results have been obtained, and an abundance of publications have appeared but only few people really use these systems. Still both the ceric-sulfate dosimeter and the oxalic-acid dosimeter may be applied successfully, once they are debugged by the people who are to use them in the daily routine. Both systems deserve much attention as they are among the few promising candidates of aqueous chemical dosimeters for use in the megarad range. 

The oxalic-acid dosimeter has some substantial advantages over the ceric-sulfate dosimeter, which made us investigate it more closely (1) it is quite insensitive to impurities, (2) it has very good energy-absorption characteristics, and (3) the system is very stable to normal storage before and after irradiation. The system also has some drawbacks (1) the decomposition of oxalic-acid does not proceed linearly with the absorbed dose, and (2) the chemical yield is not fully independent of the radiation conditions. Other difficulties have been reported and have hampered the practical use. 

Fenger (12) used the dosimeter for gamma-flux measurements in the thermal column of the DR 2 reactor and calibrated the system in the Riso Co-60 facility. He found for a 50 mM oxalic-acid solution a G-value of 4.6 0.3. 

Experience has shown that the oxalic-acid dosimeter is not as simple in use as originally anticipated. The more recent experiments have led to refinements in the analytical procedures and added to the understanding of the decomposition process. It is necessary though to calibrate the system under the conditions where it is to be used. When that is done, the system can be expected to render precise, reliable and simple service. 

Application of the Oxalic-Acid Dosimeter for High Dose-Rate Work... 

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