Exradin A12 Ion Chamber

Exradin A12 Ion Chamber

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For absolute dosimetry calibrations in water, air, or other phantom material



Exradin Farmer-type Chambers are specifically designed for absolute dosimetry calibrations in water, air, or other phantom material. The Model A12 is completely characterized in TG 51 and TRS 398.



Its waterproof construction and two piece removable stem makes it ideal for use in water phantoms. The chamber vents through a flexible tube that surrounds the triaxial cable, ensuring the collecting volume is in pressure equilibrium with the surroundings. The design assures there are no stem or voltage soakage effects, providing precise and reliable measurements.



Farmer-type Chambers are constructed of rugged C552 Shonka air-equivalent plastic, providing excellent conductivity and years of reliable use. Rigorous one meter drop test proves ruggedness and reliability.



  • Proven guard design yields stable, precise measurements and minimizes settling time by creating uniform field lines
  • Shell, collector, and guard are made of durable, long lasting Shonka conductive plastic
  • Use of homogeneous material throughout the chamber minimizes perturbation of the beam due to the presence of the chamber and optimizes measurements
  • Axially symmetric design of the chamber provides an uniform, isotropic response
  • Inherent waterproof construction eliminates need for additional protective coverings
  • Two separate stem pieces of 5.1 cm and 12.7 cm can be coupled together for ease of use
  • A matching 2.8 mm thick 60Co build-up cap of C552 Shonka air-equivalent plastic is provided for air calibrations and measurements
  • Additional build-up caps of Delrin and brass are available
  • Ionization collection efficiency is 99.9% or better
  • Collecting volume is 0.65 cc


REF Number 92700
Collecting Volume 0.65 cm3
Nominal Calibration Factor 5 R/nC
Centroid of Collecting Volume 12.9 mm from tip of chamber
Collector Diameter 1.0 mm
Outside Diameter of Shell Collecting Volume 7.1 mm
Wall Thickness 0.5 mm
Shell, Collector, and Guard Material Shonka air-equivalent plastic C552
Included 60Co Buildup Cap Wall thickness of 2.8 mm; contructed of C552
Venting Vented to the ambient via the flexible vent tube surrounding the triaxial cable
Stem 1.3 cm OD black phenolic, two-piece with 5.1 and 12.7 cm segments
Nominal Collection Efficiency 1.000
Maximum Polarizing Potential 1000 V
Nominal Inherent Leakage Currents 10-15 A
Low-Noise Triaxial Cable 50 ohms, 29 pF/ft, 1.5 m long
Signal Connector Triaxial BNC plug (2-Lug, male pin); others available upon request
High Voltage Connector Integral with triaxial connector (shell of chamber is common with connector body)
Waterproof Yes
Product Standards CE0413, Designed to meet IEC 60601-1, IEC 60731