This presentation is presented by a physics Scholar Ayat Ullah Department of Physics University: Kohat University of science and Technology Kohat

1. Topic: Radioactivity
• Subject: Radiation Detection
and Measurment
• Presented by: Ayat Ullah MS
physics Scholar.
• Department: physics Kust

2. RADIOACTIVITY:
“The phenomena of spontaneous disintegration of
unstable nuclei followed by emission of nuclear
radiation is called as Radioactivity”
“OR”
The spontaneous release of subatomic particles or
gamma rays by unstable atoms as their nuclei
tend to break apart into other particles to attain
stability is called radioactivity. An element which
possesses such property is called radioactive
element.

3. Alpha Particle:
• Alpha particle consists of two proton and two
neutron i.e., these are positively charged
helium nuclei. An alpha particle is emitted by
very a large unstable nucleus.
• It is easily stopped by cardboard or thin metal.
• Has a range in air of no more than a few
centimeter.
• Ionizes air molecules much more strongly than
the other two types of radioactive radiation.

4. Emission of Alpha Particle:
• When the ratio of neutron to proton in the
nucleus is too low, certain atoms restore the
balance by emitting alpha particles.
• When an atom disintegrates by alpha
emission, its atomic number is reduces by 2
and mass number is reduces by 4 units. The
disintegration reaction is written by.
• ZXA
Z-2YA-4 + 2He4 +Q

5. Examples of Alpha decay:
+ Q
+ Q

6. Beta Particle:
• Beta particle consists of electrons, each emitted
when a nucleus with too many neutron
disintegrates. A neutron in such a nucleus
suddenly and unexpectedly changes to a proton;
in the process, an electron is created and
instantly emitted from the nucleus. Beta
particles.
• Is stopped by 5-10 mm of metal.
• Has a range in air of about 1m.
• Ionizes air molecules less strongly than alpha-
particles.

7. Emission of Beta:
• Beta decay doesn’t change the mass number.
In essence, beta decay changes a neutron into
a proton and an electron. The proton stays in
the nucleus and the electron is ejected
energetically.
• The disintegration reaction is written by
• ZXA
Z+1YA + -1β0 +Q

8. Examples of Beta decay:
+ Q
6C14
7N14 + -1β0 + Q

9. Gamma Emission:
• Most frequently the alpha or beta emission
leaves the daughter nuclide in an exited
state. Such a nuclide may go back to a more
stable configuration and eventually to its
ground state by emitting one or more γ-rays.
Since γ-rays are massless photon, their
emission will cause no change either in A or
Z of the parent nuclide. The γ-decay process
is written as follows.
• ZXA (ZXA)*
ZXA + γ

10. THANKS
•ANY QUESTION ???