Ludlum 12-4-7

Portable neutron meter

Ludlum 12-4-7 – portable neutron meter from Ludlum Measurements. Measurement range: 0 to 100 mSv/h (0 to 10,000 mrem/hr). Weight as specified: 5.4 kg with batteries.

Detector: ³He proportional detector, 1.6 × 2.5 cm (D × L), surrounded by a 19.5 cm diameter polyethylene sphere with internal borated layer1
Measurement range: 0 to 100 mSv/h (0 to 10,000 mrem/hr)1
Weight as specified: 5.4 kg with batteries1

Download product sheet (PDF)All values with references – for tender documents

Specifications checked against the manufacturer’s documents on 2026-10-16

Manufacturer’s product page (opens in a new tab)

Overview

Nuclear power & nuclear technology Defence, security & preparedness Research & laboratories

Specifications

The number after each value refers to the source listed below. Values are as published by the manufacturer; the exact configuration is always confirmed in our quotation.

Detector

Detector	³He proportional detector, 1.6 × 2.5 cm (D × L), surrounded by a 19.5 cm diameter polyethylene sphere with internal borated layer1

Performance

Linearity	Reading within 10 % of actual value1

Measuring range

Measurement range	0 to 100 mSv/h (0 to 10,000 mrem/hr)1
Neutron sensitivity (bare ²⁴¹AmBe)	Typically 10 cpm per µSv/h (100 cpm per mrem/hr)1

Electronics & signal

Detector bias	Adjustable from 400 to 2500 V (can be read on meter)1

Power & battery

Power supply	2 "D" cell batteries1
Battery life and conditions	Typically 600 hours with alkaline batteries1

Mechanical

Dimensions (H × W × L)	38.9 x 19.6 x 22.9 cm1
Weight as specified	5.4 kg with batteries1

Environment & ratings

Operating temperature	-20 to 50 °C1

The data comes from the manufacturer’s published documents. Manufacturers may change specifications; the current configuration and performance are confirmed in the quotation.

Documents

PDFDatablad (PDF)Datasheet · Ludlum

Sources

The number after each value refers to the source listed below. Values are as published by the manufacturer; the exact configuration is always confirmed in our quotation.

1
Model 12-4-7 Neutron Dose Survey Meter
Publisher: Ludlum MeasurementsProduct page Specifications tab, 'Detector'; Specifications tab, 'Measurement Range'; Specifications tab, 'High Voltage'; Specifications tab, 'Linearity' … Checked 2026-10-16