Geiger-Müller CountersDexter Walters

Geiger Counter“Ionized Radiation Detector”[7]

Hans Geiger & Walther MüllerGeiger: German Physicist known experiment discovering nucleus

Müller: German Physicist and Philosopher (Geiger’s Student). [1,8]

Construction of “Tube”The GM tube is an airtight metal cylinder filled with gas.

One end has a window of thin mica.Positively charged wire running thru the center (Anode).

The outside of the tube (Cathode). [6,7]

How it Works

Radiation enters the GM tube and ionizes gas atoms.

Electrons are collected in microseconds while Ions are collected in milliseconds.

This results in the electrons causing an avalanche as they drift toward the anode.

Conclusion: Discharge Current to Voltage Drop

This voltage drop between the anode and cathode result from the discharge and can be detected by the counter.[6]

Assuming that we used the right gases in this counter from the start (preferably halogens), the discharge process is stopped by this lingering cloud of ions still near the anode.

Finally, the counter acts as a switch that has been closed between the voltage source and the ground.

Get to The Point!

Capacitor, Large Resistor, Anode, Cathode

What did we find?On another note until the gas inside the “tube” has returned to

its neutral state, this passage of the particles will produce no

output signal.

With now all of this in mind we know that after this discharge,

the charge Q liberated is independent of the primary

ionization:

(Q = CV)[3]

Demonstration :)

Cons of the Geiger Counter

Internal gas must restore and counter must “Recover”.

Ionization Counter and Proportional Counter

Background Noise

1. M.A. Shampo, “Hans Geiger—German Physicist and the Geiger Counter”, 2011.

2. A.C. Melissinos, “Experiments in Modern Physics”, 2003, P. 320-333.

3. K. Konrad, “Detectors for particle radiation”, Cambridge University Press, 1986, P. 52-54.

4. N.S. Gingrich, “Voltage Sources and Amplifiers for Geiger Counters”, Massachusetts Institute of Technology, 1936, P. 207-210.

5. J.R. Heirtzlert, “Electron Transit Times in Geiger Counters*”, New York University, 1953, P. 243-245.

6. “Spectrum Techniques Student Lab Manual”, Spectrum Techniques, LLC, 2014, P. 4-32.

7. Photos courtesy of myself: Dexter Walters.

8. Photos of Geiger and Muller: Google Images.

Works Cited