Chapter 4
Interaction of Radiation with Matter
4.1 Introduction
In the Chap. 2, we studied the nature of radiation normally emitted by radioactive
isotopes (i.e., either α-particle, or β-particle, or γ -ray, or mixture of them). It is also
seen that the number of such radiations emitted per unit time by an isotope is proportional to the number of atoms decaying per unit time. Therefore, for measuring
the activity of a radioactive isotope, it is appropriate to design an instrument, which
could detect and measure these radiations. Instruments, which are being used for
this purpose, can measure either ion-pairs (i.e., pair of electron-positively charged
ions) or visible light photons formed when these radiations interact with some suitable material. Therefore, it will be desirable to understand the effects caused by the
interaction of radiation with a matter (i.e., the interaction of α-particle, β-particle,
and γ -ray with a material) before discussing the principles on which different types
of detecting instruments are based.
4.2 Types of Interactions
When radiation emitted by a radioactive isotope interacts with matter (i.e., the target),
it is either scattered or absorbed by the target material. The transfer of energy from
radiation to atoms of the absorbing material may occur by several processes, but
among the commonly encountered ones, the following two are most important.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
M. Sharon and M. Sharon, Nuclear Chemistry,
https://doi.org/10.1007/978-3-030-62018-9_4
45
Interaction of Radiation with Matter
4.1 Introduction
In the Chap. 2, we studied the nature of radiation normally emitted by radioactive
isotopes (i.e., either α-particle, or β-particle, or γ -ray, or mixture of them). It is also
seen that the number of such radiations emitted per unit time by an isotope is proportional to the number of atoms decaying per unit time. Therefore, for measuring
the activity of a radioactive isotope, it is appropriate to design an instrument, which
could detect and measure these radiations. Instruments, which are being used for
this purpose, can measure either ion-pairs (i.e., pair of electron-positively charged
ions) or visible light photons formed when these radiations interact with some suitable material. Therefore, it will be desirable to understand the effects caused by the
interaction of radiation with a matter (i.e., the interaction of α-particle, β-particle,
and γ -ray with a material) before discussing the principles on which different types
of detecting instruments are based.
4.2 Types of Interactions
When radiation emitted by a radioactive isotope interacts with matter (i.e., the target),
it is either scattered or absorbed by the target material. The transfer of energy from
radiation to atoms of the absorbing material may occur by several processes, but
among the commonly encountered ones, the following two are most important.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
M. Sharon and M. Sharon, Nuclear Chemistry,
https://doi.org/10.1007/978-3-030-62018-9_4
45