Ludlum 2241-4

Portable neutron meter

Ludlum 2241-4 – portable neutron meter from Ludlum Measurements. Measurement range: 0 to 100 mSv/h (0 to 10,000 mrem/hr).

Detector: 2 atm ³He tube (LND 25185 or equivalent) in Model 42-31H neutron detector1
Measurement range: 0 to 100 mSv/h (0 to 10,000 mrem/hr)2
Weight as specified: Meter: 1.6 kg including batteries; detector: 6.56 kg2

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	2 atm ³He tube (LND 25185 or equivalent) in Model 42-31H neutron detector1

Measuring range

Measurement range	0 to 100 mSv/h (0 to 10,000 mrem/hr)2
Neutron sensitivity (bare ²⁴¹AmBe)	Typically 10 cpm per µSv/h (100 cpm per mrem/hr)1

Connectivity & interface

Detector connector	Series "C" (others available)2

Power & battery

Power supply	Two "D" cell batteries2
Battery life and conditions	Typically 200 hours; low-battery symbol alert (instrument operates for approximately 24 hours after the symbol first appears)2

Mechanical

Dimensions as specified	Meter (H × W × L): 16.5 × 8.9 × 21.6 cm; detector (H × W × D): 26.2 × 22.9 × 22.9 cm, including brackets2
Weight as specified	Meter: 1.6 kg including batteries; detector: 6.56 kg2

Environment & ratings

Operating temperature	-20 to 50 °C2
Enclosure rating and conditions	IP532

General

Moderator	22.9 cm diameter cadmium-loaded polyethylene sphere2

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

Documents

PDFModel 2241-4 Neutron Dose Ratemeter (data sheet)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 2241-4 Neutron Dose Ratemeter (data sheet)
Publisher: Ludlum MeasurementsDatasheet Detector Specifications, 'Detector'; Specifications – Sensitivity Checked 2026-10-16
2
Model 2241-4 Neutron Dose Survey Meter
Publisher: Ludlum MeasurementsProduct page Specifications tab, 'Measurement Range'; Specifications tab, 'Power'; Specifications tab, 'Battery Life'; Specifications tab, 'Temperature Range' … Checked 2026-10-16