**3. Artificial sources**

The main sources of manmade radiation that expose the public are from (Medical Procedures, as in diagnostic X-ray, radiation therapy, nuclear medicine and sterilization).

Synthesis of Polyaniline HCl Pallets and Films Nanocomposites by Radiation Polymerization 117

The International Commission of Radiation Units (ICRU) has subdivided the ionizing radiation into direct and indirect ionizing radiation, based on the mechanisms by which they ionize the atom. *Direct ionizing radiations* are fast charged particles, such as alpha particles, electrons, beta particles, protons, heavy ions, and charged mesons, which transfer their energy to the orbital electron directly and ionize the atom by means of Columbic force interactions along their track. *Indirect ionizing radiations* are uncharged quantum, such as electromagnetic radiations (X-rays and -rays), neutrons, and uncharged mesons, which undergo interactions with matter by indirectly releasing the secondary charged particles which then take turn to transfer energy directly to orbital electrons and ionize the atom. Some properties of ionizing radiation are shown in

electron

Charge +2 +1 -1 Neutral Neutral Ionization Direct Direct Direct Indirect Indirect Mass (amu) 4.00277 1.007276 0.000548 - 1.008665 Velocity (m/s) 6.944 x106 1.38 x107 2.82 x108 2.998 x108 1.38 x107 Speed of light 2.3% 4.6% 94% 100% 4.6% Range in air 0.56 cm 1.81 cm 319 cm 820 m 39.25 cm

In general the characteristic of radiation interaction with matter represented in photoelectric (*Predominates for photons in the low energy range between 10 keV and 200 keV*), Compton (*Predominated at energies of 100 keV - 10 MeV*. (McGervey, 1983)), Pair production (*Predominated at energies greater than twice the rest mass of an electron*, i.e. 2*m*0*c*2 = 1.022 MeV, *where m refers to mass of electron and c refers to speed of light* (Johns and Cunningham 1983)),

*implies both the pair production at the nucleus level plus triplet production*) and Raleigh scattering (*predominant for photons at low energy range from 1 keV to 100 keV*) table (3), is that each individual photon is absorbed or scattered from the incident beam in a single event. The photon number removed Δ*I* is proportional to the thickness traveled through x and

, where,

*x <sup>o</sup> I Ie*

the attenuation coefficient. In this case, upon integrating, we have the following equation

Triplet production process (*occurs when the incident photon have an energy of* <sup>2</sup>

<sup>1</sup> *<sup>p</sup>* or H+ <sup>1</sup> *<sup>e</sup>* or <sup>β</sup> <sup>γ</sup>- or X-rays <sup>1</sup>

Photon Neutron

0*n*

<sup>0</sup> 4*m c* , i.e. *it* 

is a constant proportionality called

(1)

Table 2. Table (2) shows the properties of different ionizing radiation.

Characteristics Alpha Proton Beta or

or He+2 <sup>1</sup>

Table 2. The properties of different ionizing radiation

**4. Gamma ray (-ray) interaction and attenuation coefficients** 

*I Ix* 

2

1 atomic mass unit (amu) = 1.6 x 10-27 kg. Speed of light c = 3.0 x 108 m/sec.

the initial photon number *I*0, i.e. *<sup>o</sup>*

(1)

Symbol <sup>4</sup>

The common radioactive elements are I-131, Tc-99m, Co-60, Ir-192, St-90 and Cs-137). Other sources exemplar in occupational and consumption products, these implies the radiation in mines, combustible fuel (gas, coal), ophthalmic glasses, televisions, luminous, watch's dial (tritium), X-ray at air-port (detectors), smoke detectors (americium-241), road construction materials, electrons tubes, and fluorescent lamp starters, nuclear fuel cell, nuclear accidents and nuclear weapons in marshal island and war. The yield of artificial sources either as quantum represented in X-ray and gamma radiation (γ) or as particles with high energy as beta particles (β), alpha particles (α), neutrons and electrons. The common artificial sources are accelerators and nuclear reactors (Smith F. A. 2000).

All of the above radiation types were used in researches; today the most common radiation sources applied in researches and in man serves are:


These energies are insufficient to initiate nuclear reaction; hence the irradiated element does not exhibit any radioactivity, see the table of radiation sources (1).


Table (1) shows the sources of radiation (Smith, 2000)

Table 1.

Ionizing radiation is a broad energetic spectrum of electromagnetic waves or high velocity atomic or subatomic particles. The radiation can be categorized according to their ability to ionize the media. Non-ionizing radiation is electromagnetic radiation that does not have sufficient energy to remove an electron of the atom. The various types of non-ionizing radiation are ultra violet (UV), visible light, infrared (IR), microwaves (radio and television), and extremely low frequency (ELF, or as they called EMF or ELF-EMF). Ionizing radiation is electromagnetic radiations, such as X-rays, -rays and charged particles (electrons, particles and -particles) which possess sufficient energy to ionize an atom by removing at least an orbital electron. According to the 1996 European Guideline of the European Atomic Energy Community (EURATOM), electromagnetic radiation with a wavelength of 100 nm or less is considered as ionizing radiation which is corresponds to ionizing potential of 12.4 eV or more (Smith, 2000). The ionization potential is dependent on the electronic structure of the target materials and generally in the order of 4 – 25 eV.

The International Commission of Radiation Units (ICRU) has subdivided the ionizing radiation into direct and indirect ionizing radiation, based on the mechanisms by which they ionize the atom. *Direct ionizing radiations* are fast charged particles, such as alpha particles, electrons, beta particles, protons, heavy ions, and charged mesons, which transfer their energy to the orbital electron directly and ionize the atom by means of Columbic force interactions along their track. *Indirect ionizing radiations* are uncharged quantum, such as electromagnetic radiations (X-rays and -rays), neutrons, and uncharged mesons, which undergo interactions with matter by indirectly releasing the secondary charged particles which then take turn to transfer energy directly to orbital electrons and ionize the atom. Some properties of ionizing radiation are shown in Table 2. Table (2) shows the properties of different ionizing radiation.


1 atomic mass unit (amu) = 1.6 x 10-27 kg.

Speed of light c = 3.0 x 108 m/sec.

116 Gamma Radiation

The common radioactive elements are I-131, Tc-99m, Co-60, Ir-192, St-90 and Cs-137). Other sources exemplar in occupational and consumption products, these implies the radiation in mines, combustible fuel (gas, coal), ophthalmic glasses, televisions, luminous, watch's dial (tritium), X-ray at air-port (detectors), smoke detectors (americium-241), road construction materials, electrons tubes, and fluorescent lamp starters, nuclear fuel cell, nuclear accidents and nuclear weapons in marshal island and war. The yield of artificial sources either as quantum represented in X-ray and gamma radiation (γ) or as particles with high energy as beta particles (β), alpha particles (α), neutrons and electrons. The common artificial sources

All of the above radiation types were used in researches; today the most common radiation

ii. Linear accelerators for photon and electron beams, with energy range of (0.3-10 MeV

These energies are insufficient to initiate nuclear reaction; hence the irradiated element does

Ionizing radiation is a broad energetic spectrum of electromagnetic waves or high velocity atomic or subatomic particles. The radiation can be categorized according to their ability to ionize the media. Non-ionizing radiation is electromagnetic radiation that does not have sufficient energy to remove an electron of the atom. The various types of non-ionizing radiation are ultra violet (UV), visible light, infrared (IR), microwaves (radio and television), and extremely low frequency (ELF, or as they called EMF or ELF-EMF). Ionizing radiation is electromagnetic radiations, such as X-rays, -rays and charged particles (electrons, particles and -particles) which possess sufficient energy to ionize an atom by removing at least an orbital electron. According to the 1996 European Guideline of the European Atomic Energy Community (EURATOM), electromagnetic radiation with a wavelength of 100 nm or less is considered as ionizing radiation which is corresponds to ionizing potential of 12.4 eV or more (Smith, 2000). The ionization potential is dependent on the electronic structure of

are accelerators and nuclear reactors (Smith F. A. 2000).

not exhibit any radioactivity, see the table of radiation sources (1).

Nuclear power 235U fission products, 90Sr, 137Cs Occupational exposure X-ray, Isotopes for (γ) ray Weapons tests 235U, 239Pu, fission products Every day sources Coal, Tobacco and Air-travel Medical tests & treatment X-ray, (γ)radiation & electrons Cosmic rays Protons, electrons, neutrons Food 40K, 137Cs, 14C and 131I Rocks & building 235U, 238U, and 232Th Atmosphere 222Rn and 137Cs

sources applied in researches and in man serves are: i. Co-60, as artificial source for gamma (γ) radiation.

Table (1) shows the sources of radiation (Smith, 2000)

the target materials and generally in the order of 4 – 25 eV.

Category Source

and up to 20 MeV).

Table 1.

Table 2. The properties of different ionizing radiation
