Gm Counter characteristics

Gm counter is invented by Hans Geiger & Walther Muller in 1920s. It is also known as Geiger-muller counter. GM counter is a device used for the detection and measurements of all type of radiation like - 𝜶 , 𝝱 , ܓ , cosmic rays.

● Experimental setup/structure ::

The apparatus consist of two part's

Metal Tube( GM tube) + [ counter + power ]

1.Gm tube :: it is hollow cylindrical tube with a wire down the center , and in tube gas filled with low temperature , gas can - Ar or He.

2. ( Counter+ power supply ) :: in general two apparatus of consist in thi part , and it high voltage controller and timer option.

● Working principal of Gm counter ::

Basicallyit consists pair of electrods surrounded by a gas , the electrods have a high voltage across them .when ionizing radiation such as 𝜶 , 𝝱 , ܓ , cosmic rays enters the tube, it can ionized some of the gas atom's in the tube from these ionized atom's , an election knocked out of the atom and remaining atom is positively charged. And the high voltage produce electric Field inside the tube . The electrons that were knocked out of the atom are attracted to the positive electrods and the positively charged ions are attracted to the negetive electrods . Then This produce a pulse of current in wire . Connecting to electrods and this pulse is counted , after the pulse is counted the charged ions become neutralized , and gm counter ready to record another pulse.

" For proper use of Gm counter , one must have that the appropriate voltage across the electrods

" If the voltage is too low , the electric Field in the tube is too weak to causes a current pulse

" The counting rate quickly rise as the voltage is increases.

" If the voltage is too high , the tube will continous discharge and tube can be damaged.