Nuclear radiation can cause significant harm to living beings. It cannot be detected by human senses. Instruments are used to detect radioactive emissions. Geiger counter is one such instrument. Also known as Geiger-Müller counter, this particle detector is used extensively to detect nuclear radiation. Alpha particles, beta particles and gamma rays are types of radioactive emissions. Geiger counter is hugely popular because it can be easily manufactured with simple electronic circuits.
The design of a typical Geiger counter consists of a metal tube (the GM tube) with a glass or mica window at one end. Particles enter the device through this end. A metal wire runs through the center of the tube. This metal wire has a strong positive charge. The sealed tube is filled (at low pressure) with an inert gas.
At high voltages, an electrical impulse is created when ionizing particles collide with gas atoms and strike the electrons from their orbit around the nucleus. The pulses are converted to readings, which are displayed to the user. Counts per minute (cpm), rem per hour (rem/hr), roentgens per hour (R/hr), milliroentgens per hour (mR/hr) and millirem per hour (mrem/hr) are some units used to measure radiation. Usually a quenching gas is added to the inert gas.
Hans Geiger (along with Ernest Rutherford) invented a device which could detect only alpha particles in the year 1908. Hans Geiger was a renowned German physicist in the early part of the 20th century. He completed his doctoral degree in physics at the University of Erlangen in the year 1906. He was working at the Victoria University of Manchester (now known as the University of Manchester) at the time of this invention. Ernest Rutherford, a New Zealand chemist and physicist, is regarded as "the father of nuclear physics."
Hans Geiger (along with Walther Müller) improvised on the device and created another counter (in the year 1928) which could detect more types of ionizing radiation. Many contemporary Geiger counters are based on this device. Walther Müller was a well-known German physicist who made significant contributions in the field of particle physics. He was the first PhD student of Hans Geiger.
The Geiger counter that is used today is also known as halogen counter. This wonderful instrument was invented by Sidney H. Liebson in the year 1947. This device is more durable than the ones invented earlier.
The Geiger counter is a wonderful invention that is used in geo physics, nuclear physics and medical therapy.