The Geiger-Müller counter is an instrument that detects ionizing radiation such as alpha particles, beta particles, and gamma rays using the ionization effect produced in a Geiger-Müller tube. It consists of a Geiger-Müller tube filled with an inert gas and high voltage that detects radiation by producing a pulse of current. Geiger counters are used to detect radioactive materials in various applications such as mineral prospecting, checking for radiation exposure or leakage, and testing for radioactive contamination of various materials.

1. Geiger Muller Counter
Presented to: Respected Dr. Kamran Sb.
Presented by: Tahir Younus
Roll No. BS-PHYS-18-44
Course: BS Physics 5th (E)
Department of Physics
Ghazi University DG Khan

2. Outline
Introduction
1
History
2
Basic Components
3
Diagram
4
Principle and Working
5
Efficiency
6
Applications
6

3.  The Geiger Counter is an instrument used for
measuring ionizing radiation. It detects ionization
radiations such as α-particles, β- particles and γ-rays
using the ionization effect produced in a Geiger-Müller
tube.
 It is perhaps one of the world’s best-known radiation
detecting instrument.
Introduction

4.  In 1908,the first model of G.M. Counter was developed by Hans Geiger and
Ernest Rutherford which was only capable of detecting α-particles.
 In1928, Geiger and Walther Muller developed advanced model of Geiger
Muller Counter consisting of sealed G.M. Tube capable of detecting all
kinds of radiations.
 Interesting fact is that it was developed under- supervision of Hans Geiger
by Walther Muller who, was PhD student of Sir Hans Geiger.
History

5. Basic Components
 A Geiger counter consists of a Geiger-Müller tube, the sensing
element which detects the radiation, and the processing
electronics, which displays the result.
 The Geiger-Müller tube is filled with an inert gas such as helium,
neon, or argon at low pressure, to which a high voltage typically
400- 600 V is applied.

6. Schematic Diagram

7. Geiger Muller Counter

8. Principle & Working
All the nuclear radiations such as alpha, beta and gamma radiation
will ionize while passing through a gaseous medium. This ionizing
property of nuclear radiations is used for the detection.
In the GM counter the central wire acts as anode and the tube acts as
cathode.

9.  When an ionizing radiation such as alpha, beta, gamma radiation enters the
tube it ionizes some of the gas molecules in tube.
 From these ionized atoms an electron comes out of atom, the remaining
atom is positively charged.
 Due to the high voltage in tube, it produces electric field.
 The electrons that come out of atom are attracted to positive electrode and
positively charged atoms are attracted to negative electrode.
 This produces a pulse of current in wires connected to electrodes and the
pulse is counted.

10. Efficiency of Geiger Muller Counter
𝐸 =
𝑁𝑜. 𝑜𝑓 𝑝𝑎𝑟𝑡𝑖𝑐𝑙𝑒𝑠 𝑜𝑓 𝑟𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛 𝑑𝑒𝑡𝑒𝑐𝑡𝑒𝑑
𝑁𝑜. 𝑜𝑓 𝑝𝑎𝑟𝑡𝑖𝑐𝑙𝑒𝑠 𝑜𝑓 𝑟𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛 𝑒𝑚𝑖𝑡𝑡𝑒𝑑

11. Precautions While Operating
 If the continuous discharge is produced, the voltage should
be lowered.
 The applied voltage must be relatively stabilized.
 Introduction of light should be prevented to avoid photo
electric effect.

12. Applications
 To detect radioactive rocks and minerals in the course of mineral
prospecting.
 To check for radioactive contamination of clothing and shoes in
your workplace.
 To check possible leakage or exposure to X-rays in a medical
facility.
 To check for radiation in areas where depleted uranium

13.  To check for irradiated gemstones in the jewellery trade.
 To check the levels of iodine 131 in cancer patients undergoing radiation therapy.
 You are in close proximity to a uranium mine and want to test the soil and
environment for dangerous levels of radioactivity.
 To test for radioactive contamination of food.
 To check materials in your anthropology or archaeology field.
Applications

14.  To check for radioactivity in metal objects in your home or office that could
be made of recycled radioactive materials.
Applications