PTW 31013, 0.3cc Semiflex Chamber

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PTW 31013, 0.3cc Semiflex Chamber.

Waterproof thimble chambers for measuring high-energy photon and electron radiation.

The semiflex chambers are designed for therapy dosimetry, mainly for dose distribution measurements in motorized water phantoms.  They have a short stem for mounting and a flexible connection cable.  The nominal useful energy range is from 30 kV to 50 MV photons and 6 MeV to 50 MeV electrons.  The wall material is graphite with a protective acrylic cover.  The guard rings are designed up to the measuring volume.  An acrylic build-up cap for in air measurement in ⁶⁰Co beams is included with each chamber, as well as a calibration certificate for calibration in absorbed dose to water or in air kerma.  Air density correction is required for each measurement.  Both chambers are shaped cylindrically with an inner diameter of 5.5 mm; they differ only in the length of the measuring volume.

• Vented sensitive volumes of 0.125 cm³ and 0.3 cm³

• Suitable for use in water phantoms

• Flat energy response within a wide energy range

The Model 31013, 0.3 cm³ chamber is used as an alternative for the 31010 chamber in cases where increased signal levels are required and spatial resolution along the axis of the chamber can be compromised.

Specifications
Type of Product:  vented cylindrical ionization chamber
Application:  absolute dosimetry in radiotherapy beams
Measuring Quantities:  absorbed dose to water, air kerma, exposure
Reference Radiation Quality:  ⁶⁰Co
Nominal Sensitive Volume:  0.3 cm³
Design:  Waterproof, vented fully guarded
Reference Point:  on chamber axis, 9.5 mm from chamber tip
Direction of Incidence:  radial
Nominal Response:  10 nC/Gy
Long-term Stability:  ≤ 1% per year
Chamber Voltage:  400 V nominal ±500 V maximal
Polarity Effect at ⁶⁰Co:  < 1%
Photon Energy Response:  ≤ ± 2% (140 kV to 280 kV),  ≤ ± 4% (140 kV to ⁶⁰Co)
Directional Response in Water:  ≤± 0.5 % for rotation around the chamber axis and for tilting of the axis up to ± 10°
Leakage Current:  ≤ ± 4 fA
Cable Leakage:  ≤ 1 pC/(Gy∙cm)

Materials and Measures: 
Wall of Sensitive Volume:  0.55 mm PMMA 1.19 g/cm³, 0.15 mm graphite 0.82 g/cm³

Total Wall Area Density:  78 mg/cm²
Dimension of Sensitive Volume:  radius 2.75 mm, length 16.25 mm
Central Electrode:  Al 99.98, diameter 0.9 mm
Build-up Cap:  PMMA, thickness 3 mm

Ion Collection Efficiency at Nominal Voltage: 
Ion collection time:  80 µs

Max. dose rate for:
> 99.5 % saturation:  14 Gy/s
> 99.0 % saturation:  28 Gy/s

Max. dose per pulse for:
> 99.5 % saturation:  0.8 mGy
> 99.0 % saturation:  1.5 mGy

Useful ranges: 
Chamber voltage:  ±100 to 400 V
Radiation quality:  40 kV to 50 MV photons (10 to 45) MeV electrons (50 to 270) MeV protons
Field size:  4 x 4 cm² to 40 x 40 cm²
Temperature:  50° - 104° F (10° - 40°C)
Humidity:  10 - 80 %, max 20 g/m³
Air pressure:  700 - 1060 hPa

Please specify which connection end is needed