The FC23-C is a shortened Farmer-type ionization chamber intended for absolute dosimetry of photon and electron beams at therapy level dose rates. Furthermore, these chambers are suitable for the dosimetry in proton fields and for depth dose measurements and field profile analysis. When calibrated accordingly, these chambers can be used for measuring the quantities absorbed dose to water, absorbed dose to air, air kerma, or exposure in air, depending upon the type and quality of radiation and the relevant code of practice.
The chamber is designed preferably for the energy ranges of photons and electrons at medical accelerators. It can also be employed in X-ray beams with generating potentials from 70 kV to 280 kV and for gamma radiation of 137Cs and 60Co. The energy range of proton beams with available chamber factors is between 50 and 250 MeV.
- Sensitive volume (nominal) 0.23 cm3
- Total sensitive length: 9.0 mm
- Total cylinder length: 6.0 mm
- Inner diameter of outer electrode: 6.2 mm
- Wall thickness of outer electrode: 0.4 mm (0.056 g/cm2 )
- Diameter of inner electrode: 1.0 mm
- Length of inner electrode 7.5 mm
- Polarizing voltage: ±300 V (max. ±500 V)
- Typical leakage current: 3 fA
- Recommended pre-irradiation: 5 Gy
- Typical sensitivity: 7.2 nC/Gy
- Guard potential: ±300 V (max. ±500 V)
- Temperature range: 15 °C – 35 °C
- Relative humidity range: 20 % – 80 %