Model 90100

Operators Manual

Recommended Operation Conditions

Source Distance: 100 cm

Collimated Field Size: 25 25 cm

Source Dose Rate Range: 50 to 500 rads/min

Nominal Ion Chamber Characteristics

Wall and Window Material: Continental Polymers ACRYCAL-CP or equivalent

Window Area Density: 600 mg/sq cm (0.51 cm acrylic plastic)

Window Transmission: 95% for 662 keV photons; for electrons, transmission through window occurs above 1.5 MeV.

Sensitivity: 3.52 R/nC at 22°C and 760 mm Hg

Active Volume: 0.93 cc ±5%

Active Diameter: 1.162 cm

Active Cross-Sectional Area: 1.06 sq cm

Collector-to-Bias Separation: 0.44 cm

Ion Transit Time: 0.418 ms @ bias voltage of 300V

Collection Efficiency: >99% at 500 rads/min pulsed; >99.9% at 500 rads/min continuous

Leakage: Less than 0.5 pA over the full operating temperature range

Ion Chamber Factory Calibration

Method: Each of the 5 ion chambers within the detector array is calibrated by comparison with a reference standard ion chamber in a Co60 beam. The comparison is performed in free air and results

in an R/nC Calibration Factor for each of the five ion chambers.

Comparison Standard: 0.6 cc NE Farmer Probe with 3 MeV buildup cap.

Uncertainty: 2.5% using IEC/NIST guidelines.

Mechanical Specifications

Detector Configuration: The detector array consists of four orthogonally placed ion chambers on 10 cm radii from a fifth centrally located ion chamber.

Dimensions: 33.7 cm wide x 43.8 cm deep x 2.2 cm high (13.25 in. x 17.25 in. x 0.875 in.). Depth dimension assumes handle is fully extended; height dimension assumes no accessory pegs or build-up added.

Weight: 4 kg (8.8 lbs)

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Fluke 90100 manual Recommended Operation Conditions, Nominal Ion Chamber Characteristics, Ion Chamber Factory Calibration