Model 44-9DOSE

Alpha-Beta-Gamma Detector with Dose Filter

Part Number: 47-3789

Ludlum offers our Model 44-9 GM pancake detector with a removable energy compensation filter that flattens the energy response to facilitate measuring Ambient Equivalent Dose (Sieverts). 

The venerable GM pancake detector has a significant over-response at lower energies between approximately 20 to 160 keV (see red line on graph below). Any dose measurements taken with an unfiltered GM pancake detector would thus have unacceptable errors at these lower energies. This  filter developed by Ludlum flattens the response to within ± 20% referenced to ¹³⁷Cs (662 keV) over an energy range of 20 keV to 1.2 MeV.

This filter simply snaps on across the face of the Model 44-9 GM pancake probe whenever this type of measurement is desired. The filter is then easily removed to measure contamination (cpm or Bq).

Note: This filter is designed to fit Model 44-9 Series of Radiation Detectors with serial number 97000 and higher. It will not fit the Model 44-9-13 or older units unless modified.

• Specifications
• Graphs
• Options
• Documents
• Replacement Parts

• Specifications
• Graphs
• Options
• Documents
• Replacement Parts

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)

---

Graphs

---

---

Options

Protective Screens

Description	Thickness	Openings	% Open	Part Number
Protective Screen (Standard)	0.25 mm (0.01 in.)	1.4 mm (0.56 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
Model 180-2	Sample holder for 5.1 cm (2 in.) max. diameter samples.	47-1665

---

Documents

• Model 44-9 Data Sheet
• Dose Filter Data Sheet
• Report

---

Replacement Parts

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

---