Ludlum Model 12-4 Neutron Counter

  • 4 Ranges
  • Splashproof Shields
  • Dose Response
  • Total Range from 0 - 10,000 mrem/hr


INDICATED USE: Neutron Survey
WORKING ENVIRONMENT: Splash proof shields for outdoor use
DETECTORS: 1.6 cm diameter X 2.5 cm thick BF³ detector surrounded by a 9"(22.9 cm) diameter cadmium loaded polyethylene sphere
SENSITIVITY: Approximately 30 cpm/mrem/hr ( AmBe neutrons )
NOTE: This unit provides an approximate inverse RPG curve for neutrons from thermal through 10 MeV
GAMMA REJECTION: Less than 10 cpm through 10 R/hr
AUDIO: Built in unimorph speaker with ON/OFF switch (greater than 60 dB at 2 feet )
METER DIAL: 0 - 10 mrem/hr, 0 - 2.5 kV, BAT TEST (others available )
MULTIPLIERS: X1, X10, X100, X1000
LINEARITY: Reading within plus or minus 10% of actual value
CALIBRATION CONTROLS: Accessible from front of instrument (protective cover provided )
HIGH VOLTAGE: Adjustable from 200 - 2500 volts (can be read on meter )
DISCRIMINATOR: Adjustable from 2 - 60 mV
RESPONSE: Toggle switch for FAST (4 seconds) or SLOW (22 seconds) from 10% to 90% of final reading
RESET: Push-button to zero meter
POWER: 2 each "D" cell batteries (housed in sealed compartment that is externally accessible )
BATTERY LIFE: Typically 600 hours with alkaline batteries (battery condition can be checked on meter )
METER: 2.5"(6.4cm) arc, 1 mA analog type
CONSTRUCTION: Cast and drawn aluminum with beige polyurethane enamel paint
TEMPERATURE RANGE: -4° F(-20° C) to 122° F(50° C)
May be certified for operation from -40° F(-40° C) to 150° F(65° C)
SIZE: 17"(43.2cm)H X 9"(22.9cm)W X 10.5"(26.7cm)L
WEIGHT: 21 lbs(9.5 kg) including batteries

Common Meter Dial

0 -10 mrem/hr


Replacement Parts

Check Source
Standard Carrying Case
Air and Water Tight Carrying Case

Meter Bezel
Meter Movement
Detector Assembly

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