MODELS2401-EC,2401-EW,2401-EC2 & 2401-P Section1
Ludlum Measurements, Inc. Page 1-1 March 2015
Introduction
he Model 2401 series of hand-held or “pocket” radiation survey
instruments are designed to quickly and easily measure ionizing
radiation. Different types are available featuring different internal
detectors. These types are distinguished from one another by a
suffix following the “Model 2401” designation. The units are self-contained
and require no external accessories.
This manual applies to the following instruments in the Model 2401 series:
Model 2401-EC - contains an energy-compensated Geiger-Mueller
(GM) tube detector, which measures low levels of gamma radiation.
One or two measurement scales are provided on the meter face (in
addition to the BAT OK range). If two scales are provided, they indicate
exposure rate and count rate. Examples of exposure rate units are
mR/hr and mSv/h, while count rate may be measured in counts per
minute (cpm) or counts per second (cps).
Model 2401-EW - has a thin end-window GM tube detector that
measures alpha, beta, and gamma radiation. The mica window has a
thickness (window area density) of 1.5 to 2.0 mg/cm2. Two
measurement scales may be provided on the meter face, as described
above.
Model 2401-EC2 - contains an energy-compensated GM tube detector.
This is basically the same as the Model 2401-EC, with the capability of
measuring higher levels of gamma radiation with corresponding
measurement scales.
Model 2401-P - employs a full-size “pancake” tube detector (5.1 cm {2
in.} diameter) that can measure alpha, beta, and gamma radiation. One
or two measurement scales may be provided on the meter face in units
of exposure rate and/or count rate, as described above.
Each instrument in the Model 2401 series has a large 6.4 cm (2.5 in.) analog
meter for displaying the radiation level. A three-decade range switch allows
the user to switch among the three ranges (×1, ×10, and ×100).
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