Spherical Chamber TK-30

Spherical ionization chamber with a long rigid stem for radiation protection measurement

Vented sensitive volume of 28 cm³
Suitable as high precision reference chamber for radiation protection dosimetry
Very flat energy response within a wide range

The spherical graphite chamber TK-30 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. Air density correction is required for each measurement.

Type of product	vented spherical
	ionization chamber
Application	radiation protection measurement
Measuring quantities	photon equivalent dose, exposure
Design	not waterproof, vented
Nominal sensitive volume	27.9 cm³
Reference point	chamber center
Direction of incidence	radial
Nominal response	900 nC/Gy
Chamber voltage	400 V nominal, ± 1000 V maximal
Energy response	≤ ± 5 % (48 keV ... ⁶⁰Co)
Directional response in air	≤ ± 0.5 % for rotation around the chamber axis
	and ≤ ± 3 % for tilting of the chamber axis up to ± 45°
Leakage current	≤ ± 5 fA

Materials and measures

Wall of sensitive volume	3 mm POM
	(polyoxymethylene),
	0.02 mm graphite
	0.22 mm lacquer
Total wall area density	453 mg/cm²
Dimension of sensitive volume
Central electrode	graphite coated PMMA,
	diameter 4.2 mm

Ion collection efficiency at nominal voltage

Ion collection time	4.5 ms
Max. dose rate for ≥ 99 % saturation	29.4 mGy/s
Max. dose per pulse for ≥ 99 % saturation	26 μGy

Ranges of use

Chamber voltage	± (200 ... 1000) V
Radiation quality	25 keV ... 50 MeV
Temperature	(10 ... 40) °C
	(50 ... 104) °F
Humidity	(10 ... 80) %, max 20 g/m³
Air pressure	(700 ... 1060) hPa