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Model 44-9

Alpha-Beta-Gamma Detector

Part Number: 47-1539

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.

Specifications

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)

Options

Protective Screens

Description	Thickness	Openings	% Open	Part Number
Protective Screen (Standard)	0.25 mm (0.01 in.)	1.4 mm (0.056 in.) square	79%	21-9586
Wire Mesh Protective Screen	1.6 mm (0.063 in.)	4.8 mm (0.188 in.) square	< 70%	7002-095-03
Protective Screen	0.25 mm (0.01 in.)	4.7 mm (0.187 in.) hex	92%	7002-1137
Protective Screen	0.25 mm (0.01 in.)	3.2 mm (0.125 in.) square	89%	7002-1138
Protective Screen	0.79 mm (0.031 in.)	4.7 mm (0.187 in.) hex	< 70%	7002-140

Option	Description	Part Number
Dose Filter	The GM pancake detector has a significant over-response at lower energies, producing dose measurement errors. The dose filter flattens the response to within ± 20% referenced to ¹³⁷Cs (662 keV) over the energy range of 20 keV to 1.2 MeV.	2002-1050
Model 180-2	Sample holder for 5.1 cm (2 in.) max. diameter samples.	47-1665

Description	Part Number
GM Tube	01-5008
Protective Screen	21-9586
Hand Grip	7002-426
Snap-In Front Cover	7002-1037
Red Protective Cap	7002-905