Geiger Counter Audio Explorer

Live Script exploring Geiger counter sounds, arrival time distribution, and nuclear radiation attenuation.

The Geiger counter is a radiation detector containing a Geiger-Muller tube sensitive to the alpha and beta particles and gamma rays emitted by atomic nuclei. Such particles can pass through the tube walls and create ionization in the contained gas. A complex amplification process produces ideally an electronic pulse of standard amplitude and few microsecond width for each detected particle. The Geiger counter counts the pulses electronically and passes pulses to a loud speaker producing characteristic clicking sounds.

A simple Geiger counter experiment uses a radioactive source producing a constant flux of particles. One can observe the particle flux decrease with distance from the source, ideally proportional to the inverse square of distance. Using a stack of sheets of material, one can observe the flux transmitted through the material decrease exponentially with thickness and measure the attenuation length characteristic of the particle and material.

This Live Script examines provided mobile phone audio recordings of a Geiger counter responding to a radioactive source at two distances from the source, and, for fixed distance, with different absorber thickness. Acoustic clicks are identified, their location in time determined, and the mean count rate measured in each case. Neglecting the detection of particles from sequential nuclear decays and interactions of the primary particles producing secondaries, each detected particle originates from a different nucleus. The nuclear emission times are uncorrelated and hence the acoustic pulse times are ideally uncorrelated. The distribution of time intervals between of successive detection events ideally derives from an exponential probability distribution. The observed distribution shows evidence for dead time associated with overlapping signals.

The script and provided audio recordings (or user recordings) may be used as an elementary instructional laboratory. It illustrates signal processing techniques including frequency analysis, bandpass filtering, peak finding and model fitting. Live Script slider controls facilitate script use. Links to function documentation are provided along with references. 'Try this' and 'Challenge' suggestions encourage exploration and may be a basis for possible assessment. This script is one of many educational Live Script offering by the author available at the File Exchange.