Spark image

Spark counter

If a match is brought up close to the gauze it will ionise the air, and sparks will occur between the gauze and wire. The same thing happens if an alpha source is used showing that the alpha particles also ionise the air as they pass through it. With beta and gamma sources insufficient ions are usually produced for sparking to take place.

 
 
 
© Keith Gibbs/John Bourne 2009