Ludlum 2401-EW

Handheld survey meter

Ludlum 2401-EW – handheld survey meter from Ludlum Measurements. Weight as specified: 0.4 kg including battery. Count-rate range: 0–210,000 cpm.

Detector: 1.4 cm diameter end-window GM tube, internal (behind protective screen)1
Weight as specified: 0.4 kg including battery1
Count-rate range: 0–210,000 cpm1

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 Emergency services & first response Environmental monitoring & radiation protection Industry & quality control

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	1.4 cm diameter end-window GM tube, internal (behind protective screen)1

Measuring range

Sensitivity (¹³⁷Cs gamma)	Typically 1050 cpm per mR/hr1
Response time	Typically 11 s from 10 % to 90 % of final reading1
Exposure rate range	0–200 mR/hr1
Count-rate range	0–210,000 cpm1
Energy response	Energy dependent1

Power & battery

Power supply	9 V battery1
Battery life and conditions	Typically 250 hours with alkaline battery at normal background levels1

Mechanical

Dimensions (H × W × L)	4.6 x 8.4 x 13.5 cm1
Weight as specified	0.4 kg including battery1

Environment & ratings

Operating temperature	−20 to +50 °C (−4 to 122 °F); may be certified for operation from −40 to +65 °C (−40 to 150 °F)2

General

Alarm	No1

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 2401-EW End-Window GM Pocket-Size Survey Meter
Publisher: Ludlum MeasurementsProduct page Specifications tab, 'Detector'; description; Specifications tab, 'Sensitivity (137Cs gamma)'; Specifications tab, 'Power'; Specifications tab, 'Battery Life' … Checked 2026-10-16
2
Ludlum Models 2401-EC, 2401-EW, 2401-EC2 and 2401-P manual
Publisher: Ludlum MeasurementsManual Manual p. 15 (p. 5-1), section 5, Environmental Conditions for Normal Use Checked 2026-10-16