Model 43-40 Series
Alpha Air Proportional Detector
PART NUMBER: 47 - 3434

INDICATED USE: Alpha survey
WORKING ENVIRONMENT: Splashproof shields and desiccant vented chamber for outdoor use
WINDOW: 0.4 mg/cm² aluminized mylar
EFFICIENCY (4pi): 10%-²³⁹Pu
BACKGROUND: 3 cpm or less
SUGGESTED INSTRUMENTS: Models 12, 16, 18, 2000, 2200, 2221, 2241, 2350
OPERATING VOLTAGE: Altitude sensitive
Sea level - 2050 volts
2000 feet - 2000 volts
5000 feet - 1925 volts
7000 feet - 1875 volts
COUNTER THRESHOLD SETTING: 2 mV
CONNECTOR: Series "C" (others available)
TEMPERATURE RANGE: -4^oF to 122^oF (-20^oC to 50^oC); may be certified for operation from -40^oF to 150^oF (40^oC to 65^oC)

Ludlum Measurements, Inc. manufacturers many different types of detectors to measure
alpha, beta, gamma, and neutron radiation.

Proportional Detectors are similar to GM in that they utilize an electric filed to produce a
signal when radiation ionizes a neutral gas molecule. Depending on the construction they
can be used to detect alpha, beta, gamma, or neutron radiation. Like GM detectors they are
inexpensive and easy to use, but they are also capable of energy discrimination. Drawbacks to
this type of detector are the fragility of the windows, altitude dependence, and a constant
need for gas replenishment (excluding sealed gas proportional tubes and air proportionals).

Common Specifications for all Detectors:
Connector: Series "C" (others available)
Construction: Aluminum housing with beige powder coat paint
Temperature Range: -4º F to 122º F (-20º C to 50º C). May be certified for operation from -
40º F to 150º F (-40º C to 65º C).

Note: All efficiencies and sensitivities are typical and different detectors may vary.


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