RADIOACTIVE ISOTOPES

Presented by:-

Palak Agrawal

INTRODUCTION Radioactive isotopes are also called as Radioisotopes. These are atoms with a different number of neutrons

than a usual atom, with an unstable nucleus that decays, emitting alpha,

beta and gamma rays until the isotope reaches stability. Once it's stable, the isotope becomes another element

entirely. Radioactive decay is spontaneous so it's often hard to

know when it will take place or what sort of rays it will emit during decay.

Radioactive nuclei emitting alpha, beta and gamma rays…

How Many?

There are around 3800 radioactive isotopes. At present there are up to 200 radioactive isotopes used

on a regular basis, and while some are found in nature. Most others have to be manufactured to suit specific

needs, such as for hospitals, research labs and manufacturers.

Periodic Table showing the Radioactive Elements…

How Are They Manufactured?

Radioactive isotopes can be manufactured in several ways.

The most common method is by neutron activation in a nuclear reactor which involves capturing a neutron by the nucleus of an atom which results in an excess of neutrons (neutron rich).

Some radioactive isotopes are produced in a cyclotron in which protons are introduced to a nucleus resulting in a deficiency of neutrons (proton rich).

Significance

Radioactive isotopes have very useful properties. Alpha, beta and gamma radiation can permeate solid

objects like an x-ray, but are progressively absorbed by them.

The amount of this penetration depends on several factors including the energy of the radiation, mass of the particle, and density of the solid.

These properties can lead to many uses for radioisotopes in the scientific, medical, archaeological and industrial fields.

The uses of radioactive isotopes in these fields depend on what element they become after they reach stability.

Isotopes as a source of radiation

This group utilizes the fact that matter modifies an incident beam of radiation giving information about the amount of material and its condition.

The amount of radiation impinging on the detector depends on the amount and kind of material put in its way so that the thickness or the density for eg. Can be quickly and accurately measured.

Radio- isotopic sources are available which emit alpha-particles, which are charged helium nuclei and are completely stopped by a piece of paper,

Beta-particles which are high velocity electrons and can penetrate up to an 8th of an inch thickness of aluminium.

Gamma rays which resemble x-rays and can penetrate several inches of steel.

A few radioactive isotopes emit x-rays arising from the x-electron capture process.

It is obvious that a fairly wide range of materials and thickness can be usefully examined using these sources.

No contact is made with the material, a continuous estimate can be given and best of all, this estimate is in the form of an electrical signal which can be used to adjust operational machinery automatically as the process is carried out.

In this way the material is consistently produced to a more strict specification.

Thin materials such as metallic foil and varnished paper for electrical condenser manufacturer, and the density of packing of cigarettes are controlled in this way.

Penetrating gamma radiation is widely used in heavy industry, for eg. In the control of strip metal production,in rolling mills and in the detection of eccentricity in the production of large diameter tubing used to make gas cylinders.

Radioactive isotopes are used as sources of radiation for the radiography of castings, welds and other products of heavy engineering.

They are tending to replace x-ray sources since they are cheap, the running cost are negligible and they are small.

This last advantage makes possible the examination of material previously regarded as inaccessible to radiography.

Unlike x-ray sources, a continuous variation in energy and optimum penetrating power cannot be provided.

The gamma rays produced by each radioactive isotope are a fixed energy unique to that nuclide.

Nevertheless, a fair amount of choice can be made. The radiation from radioactive isotopes is used to

ionise the air. This produces in effect a leakage path between the

charged surface and the nearest earthed surface, and prevents the growth of large static charges.

Uses in the Medical Field

Chromium-51, for example, which forms from emitted alpha rays during radioactive isotope decay, is used in the classifying of blood cells and measuring protein loss in the human body.

Cobalt-60, another element formed from radioactive isotopes emitting beta and gamma rays, is often used in cancer treatment.

Oxygen-18 and Technetium-99 are used as biological tracers, helping doctors locate tumors and other problems in various parts of the human body.

They are also used in x-rays and bone imaging. They are used in killing off damaged cells and treating

abnormal cell growth as rapidly dividing cells are particularly sensitive to radiation.

Uses in Archaeology and Industry

They can also be used in the field of archaeology. Radioactive isotope elements such as Carbon-14, Lead-210, and Potassium-40 are used in dating of rocks and historical earth.

Chlorine-36 and Tritium are used in measuring the age of ground water up to millions of years.

In industry they are used as fuel for nuclear reactors, in the manufacturing of domestic smoke alarms, tracing factory waste that may cause pollution, and predicting the behavior of heavy metals in water.

Sodium-24 and Magnesium-27, for example, are used to locate leaks in water pipes, while iridium-192 is used in wire in radiography devices.

REFERENCES www.wikipedia.com www.youtube.com www.2dix.com

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