PTW 30013 - Page 26

Farmer Chamber
Ionization Chamber
Type 30010, 30011, 30012, 30013
Technical Manual - Technical Specifications
26 D596.131.00/05 en
Device designation Farmer chambers
ionization chambers, types 30011, 30012
Dimensions refer to Figure 6 and Figure 7
Response 20 nC/Gy
Chamber voltage nominal +400 V
maximal ±500 V
Leakage current ≤ ±4 fA
Cable leakage ≤ 1 pC/(Gy∙cm)
Cable length 1 m
min. bending radius 20 mm (static)
min. bending radius 50 mm (for up to a maximum of 50 repetitions)
Maximum dose rate during
continuous radiation
(at nominal voltage)
99.0 % saturation
10 Gy/s
99.5 % saturation
5 Gy/s
Maximum dose per radiation
pulse (at nominal voltage)
99.0 % saturation
0.91 mGy
99.5 % saturation
0.46 mGy
Ion collection time (at nomi-
nal voltage)
140 µs
Polarity effect ≤ ±0.5 % at
60
Co
Directional response ≤ ±0.5 % for rotation around the detector axis
≤ ±0,5 % for tilting by ±5° perpendicular to the detector axis
Energy response T30011: ≤ ±12 % (280 kV ...
60
Co) reference
60
Co
T30012: ≤ ±2 % (70 ... 280) kV, reference 200 kV;
≤ ±4 % (200 kV ...
60
Co) reference
60
Co
Transient periods for
temperature equilibrium
pressure equilibrium
(2 ... 3) min/K
≤ 10 s
Pre-irradiation none
Stabilization time The response after 15 minutes and 2 hours differs by less than ±0.5 %
from the value after 1 hour.
Post irradiation leakage signal drops to < 0.5 % within 5 s after irradiation
Stability long-term stability: ≤ ±0.5 % per year
dose stability: ≤ ±1 % per 10 kGy
60
Co