Ludlum Model 3 is a portable radiation survey instrument with four linear ranges used in combination with exposure rate dials. The instrument features a regulated high-voltage power supply, unimorph speaker with audio ON/OFF capability, fast-slow meter response, meter reset button and 6-position switch for selecting battery check or scale multiples of X0.1, X1, X10 and X100. Each range multiplier has its own calibration potentiometer.
The Ludlum Model 44-2 Sodium Iodide (Nal) Gamma Scintillator Detector is primarily used for detecting low levels of gamma radiation (uR) in the range of 60 keV to 1.25 MeV. It consists of a 1-inch diameter x 1-inch thick Nal crystal coupled to a photomultiplier tube and is housed in a 0.062-inch thick aluminum housing. This combination meter and detector ships with a cable, case, and calibration certificate. An operating manual is available upon request.
- Detector: 1” diameter x 1” thick NaI Gamma Scintillation
- Meter Dial: 0 - 2 mR/hr, BAT TEST
- Meter: 2.5" (6.4 cm) arc, 1 mA analog type
- Meter Range: Typically 0-200 mR/hr
- Linearity: Reading within 10% of true value with detector connected
- Detector Sensitivity: Typically 175 µR/hr
- Connector: Series "C"
- Audio: Built-in unimorph speaker with ON/OFF switch (greater than 60 dB at 2 feet)
- Calibration Controls: Accessible from front of instrument (protective cover)
- High Voltage: Adjustable from 400 – 1500 volts (M3); 500 – 1200 volts (D44-2)
- Threshold: Fixed at 40 mV ± 10 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 (externally accessible)
- Battery Life: Typically greater than 2000 hours with alkaline batteries
- Tube: 1.7+/- 0.3 mg/cm2 mica; active – 15 cm2 & open – 12cm2
- Dynode String Resistance: 5%-14C; 22%-90Sr/90Y; 19%-99Tc; 32%-32P; 15%-239Pu
- Temperature Range: Typically 80 microseconds
- Size: -4°F(-20°C) to 122°F(50°C)