Model 9-4 Air Ion Chamber

The Ludlum Model 9-4 is a rugged air ionization chamber for performing beta-gamma dose rate measurements over a five-decade span ranging from 0-500 mSv/h (0-50 R/hr). The ion chamber automatically compensates for changes in temperature and pressure. The chamber wall, including the instrument case, is 1000 mg/cm2. A 1000 mg/cm2 retractable beta shield allows beta measurement with a 7 mg/cm2 window.

The six-position selector switch selects Off, x10K, x1K, x100, x10 and x1. Other controls include an on/off switch for a meter light, reset and battery test buttons, and a zero adjustment knob.

The Model 9-4 is equipped with a serial interface for calibration. An optional calibration kit supplies the necessary interface cable, software, calibration can, pressure pump, and serial-to-USB converter.

• 5-Decade Ion Chamber
  
• Ranges: 0-500 mSv/h (0-50 R/hr)
  
• 1000 mg/cm2 Retractable Beta Shield
  
• Automatic Temperature & Pressure Compensation
  
• Low Battery Warning
  
• High Background Zero Capability
  
• PC-Controlled Calibration

Specifications

APPLICATION: gamma and X-ray exposure survey meter with beta response
RANGE: 0-50 mSv/h (0-50 R/hr)
ENERGY RESPONSE: within 20% of true value from 40 keV-2 MeV
LINEARITY: reading within 10% of true value
RESPONSE TIME: approximately five seconds for 90% of final meter deflection on the x1 and x10 scales, and three seconds on the x100, x1k and x10k scales
BETA RESPONSE: factor of 4.8 difference between window open and closed measurements when exposed to a uranium slab
CHAMBER VOLUME: 220 cm³ (13.4 in³)
CHAMBER CONSTRUCTION: carbon coated acrylic
SIDE WALL: 1000 mg/cm² aluminum and acrylic
BETA SHIELD: retractable 1000 mg/cm² phenolic slide with side button control
WINDOW: 7 mg/cm² aluminized Mylar
WINDOW AREA: 40 cm² (6.2 in²)
COMPENSATION: automatically corrects for temperature and pressure changes in atmosphere
TEMPERATURE RANGE: -20 to 50 °C (-4 to 122 °F); temperature compensation maintains calibration within 15% of 25 °C (77 °F) reading
PRESSURE COMPENSATION RANGE: 70-106 kPa (20.7-31.3 in Hg)
METER: 6.4 cm (2.5 in.) arc, 1 mA, pivot-and-jewel suspension
METER DIAL: 0-5 mR/hr, BAT TEST (others available)

CONTROLS:
Range Switch: 5 range multipliers x1, x10, x100, x1k, x10k, and instrument OFF
Reset: pressing the reset button causes the chamber to discharge
BAT TEST: pushbutton used to check battery capacity
ZERO ADJUST: one-turn potentiometer to zero reading
Display Light: on/off switch
Calibration: digitally set via USB to serial computer interface, stored in non-voletile memory
POWER: 2 each “D” cell batteries housed in a sealed externally accessible compartment
BATTERY LIFE: 400 hours
CONSTRUCTION: cast and drawn aluminum with beige powder coating
SIZE: 23.4 x 8.9 x 21.6 cm (9.2 x 3.5 x 8.5 in.) (H x W x L) including instrument handle
WEIGHT: 1.9 kg (4.2 lb) including batteries