Model 12-4

Neutron Dose Survey Meter

Part Number: 48-1200

Features

• Moderated Neutron Detector
• Range: 0 to 100 mSv/h (0 to 10,000 mrem/hr)
• Gamma Rejection up to 0.1 Sv/h (10 R/hr)
• Rugged
• 4-Range Analog Meter

The Model 12-4 is an industry standard neutron dose rate instrument that conforms to the RPG curve with a measuring range of 0 to 100 mSv/h (0 to 10,000 mrem/hr) from thermal to 12 MeV.

The detector is a 22.9 cm (9 in.) moderated ³He tube with a gamma background rejection up to 100 mSv/h (10 R/hr). 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 count reset; and high-voltage test push-button. The Model 12-4 is a complete turn-key system and includes two "D" cell batteries.

• Specifications
• Meter Faces
• Options
• Documents
• Replacement Parts

• Specifications
• Meter Faces
• Options
• Documents
• Replacement Parts

Specifications

Indicated Use	Neutron dose rate
Detector	3He proportional detector, 1.6 x 2.5 cm (0.6 x 1.0 in.) (D x L), surrounded by a 22.9 cm (9.0 in.) diameter cadmium loaded polyethylene sphere
Measurement Range	0 to 100 mSv/h (0 to 10,000 mrem/hr)
Sensitivity (bare AmBe neutrons)	Typically 10 cpm per µSv/h (100 cpm per mrem/hr)
Energy Response	Provides an approximate inverse RPG curve for neutrons from thermal through 7 MeV, provides response up to 12 MeV
Linearity	Reading within 10% of actual value
Gamma Rejection (137Cs gamma)	< 10 cpm through 0.1 Sv/hr (10 R/hr)
Meter Dial	0 - 10 mrem/hr, 0 - 2.5 kV, BAT TEST (Meter Face tab lists other available meter faces)
Controls	Multipliers: x1, x10, x100, x1000 Response: Toggle switch for FAST (4 s) or SLOW (22 s) from 10% to 90% of final reading Reset: Pushbutton to zero meter HV Test: Pushbutton to display the high voltage on the meter Audio: Built-in unimorph speaker with ON/OFF switch (greater than 60 dB at 61 cm [2 ft])
Calibration	Accessible from front of instrument (protective cover provided)
Operating Voltage	Approximately 1200 Vdc
High Voltage	Adjustable from 400 to 2500 V (can be read on meter)
Threshold	-2 mV
Discriminator	Adjustable from 1 to 50 mV
Working Environment	Splashproof shields for outdoor use
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	Typically 600 hours with alkaline batteries (battery condition can be checked on meter)
Construction	Cast and drawn aluminum with beige powder coat finish
Size (H x W x L)	43.2 x 22.9 x 26.7 cm (17.0 x 9.0 x 10.5 in.)
Weight	8.3 kg (18.3 lb), with batteries

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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
202-438		0 - 100 μSv/hr 0 - 2.5 kV BAT TEST	Model 42-49
202-453		0 - 5 mrem/hr 0 - 2.5 kV BAT TEST	Model 42-49
202-477		0 - 10 mrem/hr 0 - 2.5 kV BAT TEST	Any
202-572		0 - 10 mrem 0 - 2.5 kV BAT TEST	Any
202-886		0 - 1.0 mrem/hr 0 - 2.5 kV BAT TEST	Any
202-1146		0 - 50 μSv/h 0 - 2.5 kV BAT TEST	Any

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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
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
Case for Neutron Meters	Rugged transport and storage case.	2310377
Case for Neutron Meters	Rugged transport and storage case. Has wheels and extendable handle.	2311487

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Documents

• Data Sheet
• Product Manual
• CE Certificate
• Ludlum Neutron Meters Comparison Table

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Replacement Parts

Description	Part Number
Detector Assembly	47-1346

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