Model 44-9 Pancake G-M Probe

For Alpha, Beta, Gamma Radiation Detection

Model 44-9 pancake G-M probe

The GM pancake-type detector in the Model 44-9 is one of the most popular radiation detectors used throughout the world. This alpha, beta, and gamma radiation detector has a rugged metal housing and is conveniently shaped and sized for checking contamination on people and objects.

This detector operates between 850 to 1000 volts, and is compatible with any Ludlum instrument capable of supplying 900 Vdc and an input sensitivity of 30 mV or higher.


Indicated Use Alpha, beta, gamma survey; Sample counting
Detector Type Pancake-type, halogen quenched G-M
Window 1.7 ± 0.3 mg/cm2 mica, protected by a stainless steel screen (79% open)
Window Area Active: 15.5 cm2 (2.4 in2)
Open: 12.3 cm2 (1.9 in2)
Efficiency (4π)
14C: 5%
90Sr/90Y: 22%
99Tc: 19%
32P: 32%
239Pu: 15%
99mTc: ≤ 1%
125I: 0.2%
Typical Sensitivity
(137Cs gamma) 3300 cpm per mR/hr
Energy Response Energy dependent (see Energy Response Curve on Graphs tab)
Typical Background
(10 µR/hr field) 60 cpm
Typical Dead Time 80 μs
Operating Voltage 900 Vdc
Connector Series "C" (others available)
Input Sensitivity ≥ -30 mV
Construction Aluminum housing with beige powder-coat finish, stainless steel screen (79% open)
Size (H x W x L) 4.6 x 6.9 x 27.2 cm (1.8 x 2.7 x 10.7 in)
Weight 0.5 kg (1 lb)