Simple Ionization Circuit:

Flat plates or concentric cylinders might be utilized in the construction of an ionization chamber. A flat plate design is preferred since it has a well-defined active volume and ensures which ions will not collect on the insulators and cause a distortion of the electric field. A concentric cylinder design does not have a well-defined active volume since of the variation in the electric field as the insulator is approached. An Ionization chamber construction differs from the proportional counter (flat plates or concentric cylinders vice a cylinder and central electrode) to permits for the integration of pulses generates through the incident radiation.  The proportional counter would needs such exact control of the electric field among the electrodes in which it would not be practical.

Figure described a simple ionization circuit consisting of two parallel plates of metal along with an air space among them. The plates are linked to a battery that is connected in series along with a highly sensitive ammeter.

Figure: Simple Ionization Circuit

The beta particles will pass between the plates and strike atoms in the air if a radioactive source that is an emitter of beta particles is placed near the detector.  Along with enough energy, the beta particle causes an electron to be ejected from an atom in air.  A single beta particle might eject 40 to 50 electrons for every centimeter of path length traveled. The electrons ejected through the beta particle frequently have sufficient energy to eject more electrons from other atoms in air. A total number of electrons generates is dependent on the energy of the beta particle and the gas among the plates of the ionization chamber.