Spherical Graphite Chambers PS- 50 and PS-10 (32007S and 32008S)

Primary standard spherical ionization chambers for radiation protection measurement

Vented sensitive volume of 50 cm³ and 10 cm³
Suitable as primary standard for radiation protection measurements
Individual determination of exact volume
Designed in collaboration with NIST (National Institute of Standards and Technology)

The spherical graphite chambers PS-50 and PS-10 are vented ionizing chambers for use as primary standard for radiation protection measurements and absolute dosimetry. They have been designed in collaboration with the Radiation Interactions and Dosimetry Group at the National Institute of Standards and Technology (NIST).

The exact volume of each chamber is determined individually. The homogeneity of the walls and electrodes is 0.06 mm.

The chambers are constructed with a long rigid stem of approx. 29 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	primary standard for radiation protection measurement
Measuring quantities	air kerma, photon equivalent dose
Design	not waterproof, vented
Nominal sensitive volume	50 cm³ (32007S)
	10 cm³ (32008S)
Reference point	chamber center
Nominal response	1.73 μC/Gy (32007S)
	0.349 μC/Gy (32008S)
Chamber voltage	1000 V nominal (32007S)
	500 V nominal (32008S)
	± 1000 V maximal
Directional response in air	≤ ± 0.5 % for rotation around the chamber axis and ≤ ± 1 % for tilting the chamber axis up to ± 60°
	(32007S), ≤ ± 1 % for tilting of the chamber axis up to ± 50° (32008S)
Leakage current	≤ ± 5 fA

Materials and measures

Wall of sensitive volume	3.5 mm graphite
Total wall area density	647 mg/cm²
Central electrode	graphite, diameter 3 mm
Outer dimensions	diameter 53 mm (32007S)
	diameter 34 mm (32008S)

Ion collection efficiency
at nominal voltage

Ion collection time	8.7 ms (32007S)
	1.9 ms (32008S)
Max. dose rate for
≥ 99.5 % saturation	1.23 mGy/s (32007S)
	26 mGy/s (32008S)
≥ 90.0 % saturation	2.46 mGy/s (32007S)
	52 mGy/s (32008S)
Max. dose per pulse for
≥ 99.5 % saturation	7.1 μGy (32007S)
	33 μGy (32008S)
≥ 99.0 % saturation	14.2 μGy (32007S)
	65 μGy (32008S)

Ranges of use

Chamber voltage	± (400 ... 1000) V
Radiation quality	⁶⁰Co, ¹³⁷Cs
Field size (square field)	≥ (6 x 6) cm² (32007S)
	≥ (4 x 4) cm² (32008S)
Temperature	(10 ... 40) °C
	(50 ... 104) °F
Humidity	(10 ... 80) %, max 20 g/m³
Air pressure	(700 ... 1060) hPa