Model 15
Technical Manual
Section 1
Ludlum Measurements, Inc.
Page 1-1
June 2020
Introduction
he Model 15 is a Neutron Counter coupled to a Model 42-14H
Neutron Detector and moderator, as well as a Model 44-7 GM
Detector. This combination provides the required electronic
circuitry and detectors for measuring and monitoring alpha, beta,
and gamma radiation, in addition to fast and slow neutrons (removable
moderator for thermal neutrons).
The instrument provides four linear ranges used in combination with a
CPM
(counts per minute) meter dial. The instrument features a regulated high-
voltage power supply, unimorph speaker with audio
ON
-
OFF
capability, fast-
slow meter response, meter reset button, and a six-position switch for
selecting battery check or range multiples of ×1, ×10, ×100, and ×1000.
Each range multiplier has its own calibration potentiometer.
Other controls include: two-position toggle switch for selection of alpha-
beta-gamma (
B
-
G
) or neutron detection (
N
), high-voltage check (
HV
) and
meter reset (
RES
) buttons, and front-panel calibration controls for
independent high voltage and discrimination adjustments.
The unit body and meter housing are made of cast aluminum and the can is
0.23 cm (0.090 in.) thick aluminum. The unit is powered by two
˝
D
˝
cell
batteries for operation from -20 to 50 °C (-4 to 122 °F). For instrument
operation below 0 °C (32 °F), either very fresh alkaline or rechargeable NiCd
batteries should be used.
Section
1
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