Rays X

In order for the Bragg spectrometer to be useful, the reflected rays must be detected. The detection of x rays is always based on their ability to eject electrons from atoms, i.e., to ionize matter. Thus the detector in the first Bragg spectrometer was an ionization chamber which collected the electric charge produced by x rays as they impacted a gas filled chamber. This ionization chamber was soon replaced by the familiar Geiger counter, developed in the study of radioactivity which was discovered at about the same time as x rays.