Model 15

Neutron Dose Survey Meter

Part Number: 48-1614

Features

• Neutron Detector with Removable Moderator
• Alpha-Beta-Gamma GM Detector
• Rugged
• 4-Range Analog Ratemeter

The Ludlum Model 15 detects and measures alphas, betas, gammas, and neutrons. A GM detector can be selected by the user to obtain alpha-beta-gamma readings. The neutron count rate measurement is provided by a ³He proportional detector that is outfitted with a removable moderator.

The ratemeter is a four-decade, analog meter designed with a cast aluminum instrument housing, incorporating a separate battery compartment and accompanying metal handle. This design delivers industrial robustness and quality, promoting long-lasting protection and instrument life. The front-panel controls include a rotary switch for selecting the four-decade range, instrument shut-off, and battery test; an audio on/off switch; a fast/slow response switch; a GM/Neutron Detector switch; a count reset; and high-voltage test pushbutton. The Model 15 is a complete turn-key system and includes two "D" cell batteries.

• Specifications
• Meter Faces
• Options
• Documents

• Specifications
• Meter Faces
• Options
• Documents

Specifications

Indicated Use	Alpha, beta, gamma, neutron detection
Neutron Detector (Model 42-14H)	Detector Type: 2 atm 3He proportional detector with 7.6 cm (3 in.) diameter, cadmium-lined (removable) moderator for thermal neutrons Sensitivity (bare 241AmBe): 55 cpm per mrem/hr Detection Range: Thermal to approximately 12 MeV Energy Response: Not linear through energy spectrum (0.025 to 12.0 MeV) Gamma Rejection (137Cs gamma): < 10 cpm through 10 R/hr
Alpha-Beta-Gamma Detector (Model 44-7)	Detector Type: Thin end-window GM detector Window: 2.0 ± 0.3 mg/cm2 mica Window Area: Active: 6.4 cm2 (1 in2); Open: 5.2 cm2 (0.8 in2) Efficiency (4π): 14C: 2%, 90Sr/90Y: 10%, 99Tc: 7%, 239Pu: 7% Sensitivity (137Cs gamma): Typically 2100 cpm per mR/hr  Energy Response: Energy dependent Background: Approximately 40 cpm
Instrument Range	0 to 500,000 cpm
Linearity	± 10% of true value
Meter Dial	0 - 500 cpm, 0 - 2.5 kV, BAT TEST (Meter Faces tab lists other available meter faces)
Meter	6.4 cm (2.5 in.) arc, pivot-and-jewel suspension
Controls	Multi-Selector Switch: Range multiplers (x1, x10, x100, x1000), Battery Check, Off Audio: On/Off switch Response Time: Pushbutton to zero meter Detector Switch: For displaying either the alpha-beta-gamma detector or neutron detector count rate High Voltage: Test pushbutton Reset: Count rate pushbutton
Audio	Built-in unimorph speaker with on/off switch, greater than 60 dB at 61 cm (2 ft.)
Working Environment	Normal working conditions
Temperature Range	-20 to 50 °C (-4 to 122 °F)
Power	2 each "D" cell batteries, housed in sealed compartment that is externally accessible
Battery Life	Approximately 600 hours with alkaline batteries, can be checked on meter
Connector	Series "C"
Size (H x W x L)	31.8 x 8.9 x 21.6 cm (12.5 x 3.5 x 8.5 in.)
Weight	3.7 kg (8.1 lb)

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Meter Faces

This table lists the most commonly used meter faces. Others are available upon request.

 

Meter Face	Image (click to view larger)	Description	Detectors
202-365		0 - 420 cpm 0 - 0.2 mR/hr 0 - 2.5 kV BAT TEST	Model 44-7
202-443		0 - 10 mrem/hr 0 - 0.8 kcpm 0 - 2.5 kV BAT OK	Model 44-7
202-719		0 - 420 cpm 0 - 2 μSv/h 0 - 2.5 kV BAT TEST	Model 44-7
202-784		0 - 10 mrem/hr 0 - 600 cpm 0 - 2.5 kV BAT TEST	Model 44-7
202-976		0 - 420 cpm 0 - 2.0 μSv/h 0 - 2.5 kV BAT TEST	Model 44-7
202-1134		0 - 5 mrem/hr 0 - 0.25 mR/hr 0 - 2.5 kV BAT TEST	Model 44-38

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Options

Option	Description	Part Number
Portable Scaler Option	Adds scaler counting capability. Includes digital readout, count time selector switch, and count control button.	4464-114
Overload Indicator Option	Adds Overload indicator with a light.	4464-130
Lighted Handle	Handle with LED to illuminate the instrument display.	4464-154
Shoulder Strap	Adjustable nylon shoulder strap.	4363-413
Headphone Jack	Adds headphone jack to instrument.	4464-464
Stereo/Mono Headphones	Adjustable stereo/mono headphones.	22-9313
Transport & Storage Case - Medium	Rugged, dust- and waterproof transport and storage case.	2311063
Plastic Disk Check Sources	General purpose check sources used to check instrument response.	Depends on source material and activity.
Mechanical Check Source Holder	Check source holder with swing-away door that attaches to instrument housing.	4062-166
Stick-On Check Source Holder	Adhesive check source holder that attaches to instrument housing.	4464-473

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Documents

• Data Sheet
• Product Manual
• CE Certificate
• Model 15 BF-3 Detector Removal Instructions
• Ludlum Neutron Meters Comparison Table

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