gm counter

gm counter

1. WEL COME

2. THANK YOU

3. RAI SAHAB BHANWAR SINGH E, COLLEG E RALA- NASRUULLAGANJ class-B.sc 5 th sem. subject-physic presentation Guided by-Mr. Gyanrao dhote sir Student name- Aarti yaduvanshi

4. GEIGER-MULLER COUNTER

5. DEFINATION- : Geiger Muller Counter is a device, which used for the detection & measurement of all types of radiation : alpha beta & gayma radiation. Basically it consist of a pair of electrodes have a high voltage across them. The gas used in usually helium or argon. PRINCIPAL-: The ionisation chamber when the potential

6. difference between the electrode is increased beyond the saturation current region ab the electrons produced due to ionisation of the atoms of the gas enclosed in the chamber by the incident particle moved toward the anode with such a velocity that they ionise the other atoms of the gas.

7. This process is called amplification. As result the ionisation current begin to increase. As the potential difference is increased the ionisation current increase .The positive sheath developed near the anode makes the electric field weak to a value below critical value required to produce Geiger discharge .as a result ,the counter becomes temporarily dead .

8. QUNCHING:-Due to successive avalanche amplification , it becomes difficult to count the fast coming pulses .hence it becomes essential that the successive are the stopped .the method adopted to stop the successive avalanche amplification ,is called qunching .

9. There are two ways used for self qunching (1)By the connecting an external resistance (2)By filling proper gas inside the chamber

10. CONSTRUCTION:-it consist of a metallic hollow cylinder C inside a glass tube , the axis of which there is a tungsten wire A nearly 0.05 mm thick , being insulated the cylinder . the tube is filled with argon and organic gas at a low pressure .To increase the life of the tube , bromine vapours . For the detection of radiations of

11. Low penetrating power ,a thin mica window w of the of the thin end is attached at one end of the tube . WORKING :-when an ionising charged particle enter the tube , it strikes the atom of the gas inside the tube & ionises it so that a pair of electron-positive ion is produced. The electron of

12. The pair is attracted toward the axial wire &the positive is attracted toward the wall of the tube so that a pulse is produced . If a is the radius of the axial wire , b is the radius of the cylinder, & the argon gas is ionised when the potential on anode relative to cathode is v volt& r radius E=V / rlog (b/a)

13. The pair is attracted toward the axial wire &the positive is attracted toward the wall of the tube so that a pulse is produced . If a is the radius of the axial wire , b is the radius of the cylinder, & the argon gas is ionised when the potential on anode relative to cathode is v volt& r radius E=V / rlog (b/a)

14. THANK YOU