摘要 : A large volume spherical ionization chamber of 195 mm diameter and 0.36 mg/cm2wall thickness made from conducting carbon-fibre epoxy composite material has been developed. The mechanical intensity of the chamber is satisfactory fo... 展开 A large volume spherical ionization chamber of 195 mm diameter and 0.36 mg/cm2wall thickness made from conducting carbon-fibre epoxy composite material has been developed. The mechanical intensity of the chamber is satisfactory for a good longterm volume stability. Owing to its large volume and thin wall, the chamber is sensitive to low energy photon beams and has excellent energy-response characteristics. This ionization chamber is suitable not only for a laboratory reference but also for measurement of low energy photon beam exposure rates at protection-level. 收起