geiger muller counter

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Index

1 Intro about project and device and its uses

2 inventor

3 radiology

4 making of device

5 how it functions

6 detailed use

7 application in current world

8 thank you
S.NO Topic Page.no

1 Introduction

2 Inventor

TABLE OF CONTENT
 INTRODUCTION

A Geiger counter also known as a Geiger–Müller

counter or G-M counter is an electronic instrument used for
detecting and measuring ionizing radiation. It is widely used in
applications such as radiation dosimetry, radiological
protection, experimental physics and the nuclear industry.
It detects ionizing radiation such as alpha particles, beta
particles, and gamma rays using the ionization effect produced
in a Geiger–Müller tube, which gives its name to the instrument.
In wide and prominent use as a hand-held radiation survey
instrument, it is perhaps one of the world's best-known radiation
detection instruments.
The original detection principle was realized in 1908 at
the University of Manchester, but it was not until the
development of the Geiger–Müller tube in 1928 that the Geiger
counter could be produced as a practical instrument. Since
then, it has been very popular due to its robust sensing element
and relatively low cost. However, there are limitations in
measuring high radiation rates and the energy of incident
radiation.
The Geiger counter is one of the first examples of data
sonification. This was a major breakthrough for the nuclear
industry.
The introduction in July 1928 of the Geiger-Müller counter
marked the introduction of modern electrical devices into
radiation research.
 ITS INVENTION

In 1908 Hans Geiger, under the supervision of Ernest

Rutherford at the Victoria University of Manchester (now
the University of Manchester), developed an experimental
technique for detecting alpha particles that would later be used
to develop the Geiger–Müller tube in 1928. This early counter
was only capable of detecting alpha particles and was part of a
larger experimental apparatus.
The fundamental ionization mechanism used was discovered
by John Sealy Townsend between 1897 and 1901, and is
known as the Townsend discharge, which is the ionization of
molecules by ion impact.
It was not until 1928 that Geiger and Walther Müller (a PhD
student of Geiger) developed the sealed Geiger–Müller tube
which used basic ionization principles previously used
experimentally. Small and rugged, not only could it detect alpha
and beta radiation as prior models had done, but also gamma
radiation. Now a practical radiation instrument could be
produced relatively cheaply, and so the Geiger counter was
born. As the tube output required little electronic processing, a
distinct advantage in the thermionic valve era due to minimal
valve count and low power consumption, the instrument
achieved great popularity as a portable radiation detector.
Geiger, the eldest of 5 children of a professor of philology, was
born on September 30, 1882, in Neustadt an der Hardt,
Rhineland-Palatinate state in western Germany (about 20 miles
southwest of Mannheim). He studied physics at the universities
of Munich and Erlangen in Bavaria, Germany, and received the
PhD degree from the latter university in 1906. At the University
of Erlangen, he worked with Eilhard Wiedemann (1852-1928)
and wrote a thesis on electrical discharges through gases.
Geiger received a fellowship that enabled him to work as an
assistant to physicist Arthur Schuster (1851-1934) at the
University of Manchester (England). After Schuster’s retirement
in 1907, Geiger continued to work with Schuster’s successor,
Ernest Rutherford (1871-1937). In 1908, Rutherford and Geiger
devised a counter for alpha particles, work that led to
Rutherford’s nuclear theory of the atom, for which he won the
1908 Nobel Prize in chemistry. They used the counter and other
radiation detectors in experiments that led to the identification
of the alpha particle as the nucleus of the helium atom and to
Rutherford’s correct proposal (1912) that, in any atom, the
nucleus occupies a very small volume at the center. Geiger
remained in England until 1912, when he was named head of
the German National Institute of Science and Technology in
Berlin, where he continued his studies on atomic structure and
radiation counting.
In 1913, Geiger was joined by two physicists, Walther Bothe
(1891-1957), later the 1954 Nobel Prize winner in physics, and
James Chadwick (1891-1974), later Sir James Chadwick and
winner of the 1935 Nobel Prize in physics. Bothe investigated
alpha scattering, and Chadwick counted beta particles. The
work was interrupted in 1914, with the beginning of World War I
(1914-1918). Geiger served in the German army in the field
artillery.
After the war, Geiger returned to his work, and in 1924, he used
his device to confirm the Compton effect, namely, the increase
in wavelength of electromagnetic radiation, especially of an X-
ray or gamma-ray photon, scattered by an electron. The
Compton effect was discovered by the American physicist
Arthur Holly Compton (1892-1962), for which he was awarded
the 1927 Nobel Prize in physics.
In 1925, Geiger accepted his first teaching position, which was
at the University of Kiel, Germany. Here, he and Walther Müller
improved the sensitivity, performance, and durability of the
counter, and it became known as the “Geiger-Müller counter.” It
could detect not only alpha particles but also beta particles
(electrons) and ionizing photons. The counter was essentially in
the same form as the modern counter.
In 1929, Geiger moved to the University of Tübingen
(Germany), where he was named professor of physics and
director of research at the Institute of Physics. In 1929, while at
the Institute, Geiger made his first observations of a cosmic-ray
shower. Geiger continued to investigate cosmic rays, artificial
radioactivity, and nuclear fission after accepting a position in
1936 at the Technische Hochschule in Berlin, a position he held
until his death. In 1937, with Otto Zeiller, Geiger used the
counter to measure a cosmic-ray shower.
During World War II (1939-1945), Geiger participated briefly in
Germany’s abortive attempt to develop an atomic bomb. In
June 1945, Geiger fled the Russian occupation of Berlin and
went to nearby Potsdam, where he died on September 24,
1945, at the age of 62 years, less than 2 months after the
American atomic bomb was dropped on Hiroshima, Japan.
Geiger was honored on a stamp (Scott No. 2182) issued in
1998 by Antigua and Barbuda.
 RADIOLOGY

In physics, radiation is the emission or transmission

of energy in the form of waves or particles through space or a
material medium.
Radiation is often categorized as either ionizing or non-
ionizing depending on the energy of the radiated particles.
Ionizing radiation carries more than 10 electron volts (eV),
which is enough to ionize atoms and molecules and
break chemical bonds.
This is an important distinction due to the large difference in
harmfulness to living organisms. A common source of ionizing
radiation is radioactive materials that emit α, β, or γ radiation,
consisting of helium nuclei, electrons or positrons, and photons,
respectively. Other sources include X-rays from
medical radiography examinations and muons, mesons,
positrons, neutrons and other particles that constitute the
secondary cosmic rays that are produced after primary cosmic
rays interact with Earth's atmosphere.

 Ionizing radiation :
Radiation with sufficiently high energy can ionize atoms; that is
to say it can knock electrons off atoms, creating ions. Ionization
occurs when an electron is stripped (or "knocked out") from an
electron shell of the atom, which leaves the atom with a net
positive charge. Because living cells and, more importantly, the
DNA in those cells can be damaged by this ionization, exposure
to ionizing radiation increases the risk of cancer.
The source of the ionizing radiation is a radioactive material or
a nuclear process such as fission or fusion. Most ionizing
radiation originates from radioactive materials and space
(cosmic rays), and as such is naturally present in the
environment, since most rocks and soil have small
concentrations of radioactive materials. Since this radiation is
invisible and not directly detectable by human senses,
instruments such as Geiger counters are usually required to
detect its presence.

 Radiation dosimetry
Radiation dosimetry in the fields of health
physics and radiation protection is the measurement,
calculation and assessment of the ionizing radiation dose
absorbed by an object, usually the human body. This applies
both internally, due to ingested or inhaled radioactive
substances, or externally due to irradiation by sources of
radiation.
The Geiger Muller Counter plays a vital role in this industry.

 Radiation protection
Radiation protection, also known as radiological protection, is
defined by the International Atomic Energy Agency (IAEA) as
"The protection of people from harmful effects of exposure
to ionizing radiation, and the means for achieving this".
Exposure can be from a source of radiation external to the
human body or due to internal irradiation caused by the
ingestion of radioactive contamination.
Ionizing radiation is widely used in industry and medicine, and
can present a significant health hazard by causing microscopic
damage to living tissue.
Various industries use the Geiger counter to detect radiation
and to ensure their safety.

 Experimental physics
Experimental physics is a branch of physics that is concerned
with data acquisition, data-acquisition methods, and the
detailed conceptualization (beyond simple thought
experiments) and realization of laboratory experiments.
Physicists such as Galileo Galilei, Christiaan
Huygens, Johannes Kepler, Blaise Pascal and Sir Isaac
Newton occupied this field
The nuclear and radiology sectors of physics continue to grow
till this day as the endless possibilities are forever unravelling in
the world of science.

 Nuclear industry
Nuclear power is the use of nuclear reactions to
produce electricity. Nuclear power can be obtained
from nuclear fission, nuclear decay and nuclear
fusion reactions. Presently, the vast majority of electricity from
nuclear power is produced by
nuclear fission of uranium and plutonium in nuclear power
plants. Nuclear decay processes are used in niche applications
such as radioisotope thermoelectric generators in some space
probes such as Voyager 2.
Deduction of radioactive material and nuclear reactive
substance is crucial in this line of work and it is necessary for
the safety ,this is where a Geiger counter comes in place.
Worldwide disasters like the 1979 Three Mile Island accident in
the United States and the 1986 Chernobyl disaster in the Soviet
Union and the Fukushima nuclear disaster in Japan in 2011
and the Trinity test could have been prevented with proper
radiation readings and would be easy with devices like the
Geiger counter.

 Radioactivity
Radioactivity is the spontaneous emission of energy from the
nucleus of certain atoms. The most familiar radioactive material
is uranium. There are three forms of energy associated with
radioactivity; alpha, beta and gamma radiation. The
classifications were originally determined according to the
penetrating power of the radiation. Our Geiger Counter can
detect the three types of radiation; alpha, beta and gamma
radiation.
Alpha radiation are the nuclei of helium atoms, two protons and
two neutrons bound together. Alpha rays have a net positive
charge. Alpha particles have weak penetrating ability, a couple
of inches of air or a few sheets of paper can effectively block
them.
Beta radiation were found to be electrons, identical to the
electrons found in atoms. Beta rays have a net negative
charge. Beta rays have a greater penetrating power than Alpha
rays and can penetrate 3mm of aluminum.
Gamma radiation are high-energy photons. This has the
greatest penetrating power being able to pass through several
centimeters of lead and still be detected on the other side.
Thick lead is needed to attenuate gamma radiation.
 Making of the Device
(or)Function of device
The Geiger Counter produces an audible click and blinks a LED
each time it detects a radioactive particle. It has a Data output
jack, that outputs a +5V pulse every time a radioactive particle
is detected. It also has a headphone jack for private listening.
Typically the Geiger counter clicks 10-20 times a minute due to
normal background radiation. While the device is sensitive
enough to measure background radiation, it is not suitable for
measuring radon gas. There are Radon gas detectors that use
an activated charcoal filter that are easy to use and more
accurate. It's expandable. You can enhance the basic Geiger
Counter by adding a Digital Meter Adapter (DMAD) that adds a
digital output for the Counts Per Second (CPS). The DMAD
when used with a USB TTL adaptor can use a Windows
Radiation monitoring program .
Even if we were to built our own Geiger counter we would face
many problems like soldering the circuit and calibrating the
device or building the correct geiger tube

 Detecting Radiation-The Geiger Mueller

Tube
Geiger Mueller tubes are simple devices that detect
and measure radioactivity. The original design by H.
Geiger and E.W. Mueller in 1928 hasn't change very
much. The basic sensor functioning remain the same.

A cut away drawing of a typical Geiger Mueller (GM)

tube is shown in. The wall of the GM tube is a thin
metal (cathode) cylinder surrounding a centre electrode
(anode). The metal wall of the GM tube serves as the
cathode of the GM Tube. The front of the tube is a thin
Mica window sealed to the metal cylinder. The thin
mica window allows the passage and detection of the
weak penetrating alpha particles.

The GM tube is first evacuated then filled with Neon,

Argon plus Halogen gas.

Our GM tube is put into an initial state (ready to detect

a radioactive particle), by applying + 500-volt potential
to the anode (center electrode) through a ten mega
ohm current limiting resistor. A 470K-ohm resistor is
connected to the metal wall cathode of the tube and to
ground. The top of the 470K resistor is where we see
our pulse signal whenever a radioactive particle is
detected.

In this initial state the GM tube has a very high

resistance. However, when a radioactive particle passes
through the GM tube, it ionizes the gas molecules in its
path and creates a momentary conductive path in the
gas. This is analogous to the vapor trail left in a cloud
chamber by a particle. In the GM tube, the electron
liberated from the atom by the particle, and the
positive ionized atom both move rapidly towards the
high potential electrodes of the GM tube. In doing so
they collide with and ionize other gas atoms, creating a
momentary avalanche of ionized gas molecules. And
these ionized molecules create a small conduction path
allowing a momentary pulse of electric current to pass
through the tube allowing us to detect the particle.

This momentary pulse of current appears as a small

voltage pulse across the 470 K ohm resistor. The
halogen gas quickly quenches the ionization and the
GM tube returns to its high resistance state ready to
detect more radioactivity.
  GM Tube's Dead Time
For the short amount of time the GM tube is detecting
one particle, if another radioactive particle enters the
tube it will not be detected. This is called dead time.
The maximum dead time for our GM tube is 90
microseconds (or .00009 seconds). There is a
mathematical formula for adjusting a Geiger counter
read out to compensate for the GM tube's dead time.
However the adjust is so small that for practical
applications it can be ignored. High-end nuclear work
will take a tube's dead time into consideration.