Optical ionization detector

A method for detecting the passage of a charged particle through a beam of light by a change of index of refraction in the light beam, including the steps of:

• splitting a beam of light into two arms;
• directing one arm of the light beam into an ionization chamber;
• directing the other arm of the light beam through a fiber optic;
• providing the ionization chamber with an ionizable gas;
• forming an electric field through the gas such that upon a charged particle being directed into the gas causes at least one electron to be freed when the gas is ionized by the charged particle and accelerated through by electric field causing the generation of an electron avalanche;
• passing the one arm of the light beam through the gas whereby an electron avalanche causes a change in the density of the gas and a corresponding change in the index of refraction of the gas within the light beam arm passing therethrough;
• directing the one arm of the light beam out of the ionization chamber;
• recombining the two arms of the light beam;
• and
• determining the passage of a charged particle through the gas in the ionization chamber via the measurable interference fringe changes in the two arms of the light beam due to the change of the index of refraction of the one light beam arm.

A detector of ionizing radiation using optical interferometry to detect density changes in a gas when charged particles pass through the gas, comprising:

• means for producing a beam of light;
• means for splitting said light beam into a plurality of arms;
• fiber optic means having one end adjacent said light beam splitting means for receiving one of said arms of said light beam;
• an ionization chamber positioned to receive another of said arms of said light beam;
• said ionization chamber including an ionizable gas and means for producing an electric field through at least a portion of said gas, such that when a charged particle traverses the gas it frees an electron which is accelerated in said electric field to form an electron avalanche which changes the density of the gas which causes a change in the index of refraction of the gas as a light beam passes therethrough;
• said other arm of said light beam passing through said ionizable gas in said ionization chamber exiting from said chamber, and passing to a point of recombining with said one arm of said light beam as it exits from said fiber optic means;
• and
• means for measuring interference changes that are a function of the index of refraction change in said other arm of said light beam, thereby providing an indication of the passage of a charged particle through the ionizable gas.