abhishek mishra

1. GENERAL TECHNIQUES FOR THE
DETECTION OF RADIOISOTOPES
Team Members
Abhishek kr. Mishra [A7104421010]
Nikhil Singh [A7104421016]
Ritesh Pandey [A7104421012]
Aryan Shukla [A7104421014]
Teacher
Dr. Gurjeet Kaur
Subject
Good lab practices and
Instrumentation

2. What is Radioisotopes
Radioisotopes/ radioactive isotopes of an element can be defined as atoms that contain
an unstable nucleus and dissipate excess energy by spontaneously emitting radiation in
the form of alpha, beta and gamma rays.
A radioisotope is an isotope of an element that undergoes spontaneous decay and emits
radiation as it decays.
During the decay process, it becomes less radioactive overtime, eventually becoming
stable.
Once an atom reaches a stable configuration, it no longer gives off radiation.

3. TYPES OF RADIOACTIVE DECAY
Radioactive decay is the process by which an unstable atomic nucleus loses energy by
radiation. There are three types of radioactive decay:
• Alpha Decay (Helium nucleus is emitted)
It’s a type of radioactive decay in which an atomic nucleus emits an alpha particle.
• Beta Decay (Electrons are emitted)
It is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is
emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide.
• Gamma Decay (High energy photons are emitted)
Gamma decay is the emission of electromagnetic radiation of an extremely high frequency i.e.
very high energy, giving out excess energy in order to stabilize the unstable nucleus.

4. Application Of Radioisotopes
Nutritional and food Science :
• The identification of primary and secondary food sources, elucidating predator/ prey relationship
and constructing food webs.
• Tracing nutrient and mineral uptake by plants and animals.
• Determining the relative importance of plants and microbes of greenhouse gas emission from soil.
Measuring environmental stressors by monitoring plant uptake of CO2 and / water.
In the field of Geology
• Radiogenic isotopes are an extremely useful means to determine geological stratigraphy and
diagenesis from geological materials.
• For example, working with partners in the oil and gas industry (Isotopic Ltd). We can analyse the
Strontium (Sr) isotope ratio of the salts from production waters and/or cores of any vintage to
characterised reservoir stratigraphy, Compartmentalisation and connectivity.

5. In chemistry -Radio Isotopic Labeling
• The use of isotopes is very common in Isotopic Labeling. Unusual isotopes are used as tracers or
markers in chemical reactions.
• Atoms of an element generally cannot be distinguished from one another. These atoms can be
distinguished using Mass Spectrometry or Infrared Spectroscopy, where isotopes of different
masses are used.
• Radiations of radioactive isotopes can be used for detecting various reactants, rates, and so on in
chemistry.
In Industry
• Radioactive isotopes of various kinds are used for measuring the thickness of metal or plastic
sheets; their precise thickness is indicated by the strength of the radiations that penetrate the
material being inspected.
• They also may be employed in place of large X-ray machines to examine manufactured metal
parts for structural defects.
• Other significant applications include the use of radioactive isotopes as compact sources of
electrical power—e.g., plutonium-238 in spacecraft.

6. General Techniques for the Detection of Radioisotopes
Human senses cannot detect alpha, beta or gamma radiation, so we need equipment to do this.
Radioisotopes can be detected by the following:
Photographic film
Photographic film goes darker when it absorbs radiation, just like it does when it absorbs visible light.
The more radiation the film absorbs, the darker it is when it is developed.
People who work with radiation wear film badges, which are checked regularly to monitor the levels
of radiation absorbed.
There is a lightproof packet of photographic film inside the badge. The more radiation this absorbs,
the darker it becomes when it is developed.
To get an accurate measure of the dose received, the badge contains different materials that the
radiation must penetrate to reach the film. These materials may include aluminium, copper, lead-tin
alloy and plastic.

7. Geiger-Muller Counter
A Geiger counter is a metal cylinder filled with low-pressure gas sealed in by a
plastic or ceramic window at one end. Running down the center of the tube there's
a thin metal wire made of tungsten. The wire is connected to a high, positive voltage
so there's a strong electric field between it and the outside tube.
When radiation enters the tube, it causes ionization, splitting gas molecules into
ions and electrons. The electrons, being negatively charged, are instantly attracted
by the high-voltage positive wire and as they zoom through the tube collide with
more gas molecules and produce further ionization.
The result is that lots of electrons suddenly arrive at the wire, producing a pulse of
electricity that can be measured on a meter and (if the counter is connected to an
amplifier and loudspeaker) heard as a "click." The ions and electrons are quickly
absorbed among the billions of gas molecules in the tube so the counter effectively
resets itself in a fraction of a second, ready to detect more radiation.

8. Scintillation counter
Scintillation Counter is an instrument that is used for measuring ionizing radiation. It comprises the
scintillator that generates photons in response to incident radiation, a PMT tube is used to convert
an electronics and electric signal to process the signal.
A scintillation counter is used to detect gamma rays and the presence of a particle.
Autoradiography
Autoradiography is a detection method in which X-ray or photographic film is exposed to emissions
from radioisotopes on TLC plates to produce an image on the film.
After exposure, the film is developed to reveal the location of the areas of radioactivity as darkened
spots or zones of varying optical density. The density is related to the amount of radioactivity in the
zone.