(800) 622-0828 (US, CA)
(325) 235-5494
(325) 235-4672

To search products by model number, enter "m..."
(Ex: Enter "m3" to search for Model 3.)

Health Physics Medical Physics Metal Recycling Monitoring Systems Emergency Response

Health Physics

Need Help?

Unsure about which instrument is best for your application?

Find your region's Ludlum representative or dealer.

Contact Ludlum Sales:

(800) 622-0828 (USA Toll Free)

(325) 235-5494

Model 42-30H

Neutron Detector

Part Number: 47-3582

The Ludlum Model 42-30H Neutron Detector is designed for detection of thermal and fast neutrons (0.025 eV to approximately 12 MeV). The neutrons are detected, not directly, but through nuclear reactions, which result in energetic charged particles such as protons and tritons. In many instances, intense fields of gamma rays are also found with neutrons. Therefore, it is important to choose a method of neutron detection with the ability to discriminate against these gamma rays in the detection process.

A common reaction for the conversion of slow neutrons into directly detectable particles is n + 3He → 3H + 1H + 0.764 MeV. The Ludlum Model 42-30H utilizes this reaction in the form of helium-3 (³He), which fills the gas proportional tube of the detector.

The Model 42-30H is typically used with area monitors. To detect neutrons with energies above the thermal region, the detector is placed inside the moderator. The detector can be removed from the moderator for the detection of thermal neutrons.

Specifications

Description	Wall mount proportional neutron detector
Detector Type	2 atm ³He tube (LND 25185 or equivalent)
Moderator	25.4 cm (10.0 in.) diameter polyethylene sphere
Detection Range	Thermal to approx. 12 MeV
Energy Response	Approximately follows the radiation protection guide curve for neutron dose
Sensitivity (²⁴¹AmBe)	20,000 cpm per mSv/h (200 cpm per mrem/hr) (typical)
Gamma Rejection (¹³⁷Cs)	10 cpm or less up to 0.1 Sv/h (10 R/hr)
Operating Voltage	1200 V (typical)
Threshold	-2 mV
Connector	Series "C" (others available)
Construction	Polyethylene moderator with aluminum housing and mounting bracket
Size (H x W x L)	38.1 x 25.4 x 26.2 cm (15.0 x 10.0 x 10.3 in.), includes mounting bracket
Weight	8.8 kg (19.5 lb)

Suggested Instruments

Model	Description	Part Number
Model 177-50	Benchtop Analog Meter 5-decade logarithmic scale Adjustable audio & visual alarm HV Range: 400 to 2500 V	48-1202
Model 177-61	Benchtop Analog Meter 4-decade linear scale Adjustable audio & visual alarm HV Range: 400 to 2500 V	48-1382
Model 375	Area Monitor Controller	48-2230