Description: A geiger counter and a selection of radioactive sources.
Available sources are: Thallium 204 (beta); Strontium 90 (beta); Cobalt 60 (gamma); Coleman propane lamp mantle containing hydroxides and nitrates of Thorium; Americium 241 smoke detector source; wrist watch with Radium dial
The counter is a Ludlum Model 3 Survey Meter. The meter may be connected to an overhead projection meter for a visual indication of the count rate (survey meter output is 1V fullscale, run through unity gain buffer on OHP meter to avoid loading survey meter output). The survey meter audio is more useful. From the manual for this instrument:
3. Description of controls and functions
Range Multiplier Selector Switch is a 6-position switch marked OFF, BAT, X100, X10, X1, X0.1. Turning the range selector switch from OFF to BAT position provides the operator a battery check of the instrument. A BAT check scale on the meter provides a visual means of checking the battery status. Moving the range selector switch to one of the range multiplier positions (X100, X10, X1, X0.1) provides the operator with an overall range of 0-500K counts per minute. Multipl the scale reading by the multiplier for determining the actual reading.
AUDIO ON-OFF Toggle Switch in the ON position operates the unimorph speaker, located on the left side of the instrument. The frequency of the clicks is relative to the rate of incoming pulses. The higher the rate is, the higher the audio frequency. The audio should be turned OFF when not required to reduce battery drain.
Fast-Slow Toggle Switch provides meter response. Selecting the "F" position of the toggle switch provides 90% of the final reading in 4 seconds. In "S" position, 90% of the final meter reading takes 22 seconds. In "F" position there is fast response and large meter deviation. In "S" position there is a slow response and damped meter deviation.
Cautions:
Concepts demonstrated:
Setup Time: Short
Difficulty/Commitment: Straightforward
Visibility: Visible
Related demonstrations:
References: PIRA 7D10.10, 7D30.xx