LUDLUM Model 15 Neutron Dose Survey Meter

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.

 

Features:

Neutron Detector with Removable Moderator

Alpha-Beta-Gamma GM Detector

Rugged

4-Range Analog Ratemeter

 

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)