Cylindrical Reference Chamber 23361

  • Vented sensitive volume of 30 cm³
  • Suitable as high precision reference chamber for radiation protection dosimetry
  • Very flat energy response within a wide range

The cylindrical stem chamber has been designed as a reference chamber for absolute dosimetry to be used by secondary standard dosimetry laboratories (SSDL) and users with high quality requirements. It has very small variations of response with radiation quality from low X-ray energies up to high-energy photon radiation.

The guard ring is designed up to the sensitive volume.

The chamber is constructed with a long rigid stem of approx. 20 cm length for easy mounting in the radiation beam. An acrylic build-up cap with 3 mm wall thickness for in-air measurement in 60Co beams is included with each chamber, as well as a calibration certifiate.

Air density correction is required for each measurement. A radioactive check device with an appropriate holder is optionally available.

Type of product vented cylindrical
  ionization chamber
Application radiation protection measurement
Measuring quantities air kerma, photon equivalent dose, exposure
Design not waterproof, vented
Nominal sensitive volume 30 cm³
Reference point on chamber axis, 27 mm from chamber tip
Direction of incidence radial
Nominal response 1 μC/Gy
Chamber voltage 400 V nominal, ± 500 V maximal
Energy response ≤ ± 4 % (40 keV ... 60Co)
Directional response in air ≤ ± 0.5 % for rotation around the chamber axis,
Leakage current ≤ ± 10 fA
Stem leakage ≤ 1 pC/(Gy·cm)

Materials and measures

Wall of sensitive volume 1 mm PMMA, graphited
Total wall area density 119 mg/cm2
Dimension of sensitive volume radius 15.5 mm, length 51 mm
Central electrode graphite coated Al
  diameter 14 mm
Outer dimensions diameter 33 mm
  length 335 mm
Build-up cap PMMA, thickness 3 mm

Ion collection efficiency at nominal voltage

Ion collection time 1.3 ms
Max. dose rate for  
≥ 99.5 % saturation 60 mGy/s
≥ 90.0 % saturation 120 mGy/s
Max. dose per pulse for  
≥ 99.5 % saturation 50 μGy
≥ 99.0 % saturation 100 μGy

Ranges of use

Radiation quality 30 keV ... 50 MeV
Temperature (10 ... 40) °C
  (50 ... 104) °F
Humidity (10 ... 80) %, max 20 g/m³
Air pressure (700 ... 1060) hPa


T48010 Radioactive check device 90Sr
T23237 Chamber holding device for check device
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