1. Geiger-Mueller Counters Darwin L. Boyd Kent State University School of Technology

2. Gas Filled Counters Ion chambers Proportional counters Geiger-Mueller counters

3. Charged Particle Interactions Alpha particles (He nuclei) and fast electrons (beta particles) interact with matter via the Coulomb force and produce ionization - ion pairs. 30 eV per ion pair Ion pairs would like to recombine Can be collected by applying an electric field

4. Gas Filled Counter Image from: http://www-istp.gsfc.nasa.gov/Education/wgeiger.html

5. Gas Filled Counters Pulse Amplitude Applied Voltage Ion chambers Proportional Counters Geiger Counters

6. Gamma Ray Interactions Gamma Rays (and X Rays) do not interact via the Coulomb force Must undergo a “catastrophic” event Result is a fast electron “Catastrophic” event usually occurs in the walls of gas filled detectors