1. Radiation Safety Training Basic Radiation Physics Washington State University Radiation Safety Office

2. Radiation Fundamentals
Objectives:
Identify the three basic particles of an atom
Define radioactive material, radioactivity, radioactive half-life
Define ionization and ionizing radiation
Distinguish between ionizing radiation and non-ionizing radiation
Identify the four basic types of ionizing radiation
Physical characteristics
Range
Shielding
Biological hazards

3. What is an Atom

4. The basic unit of matter is the atom.
Atomic Structure
The basic unit of matter is the atom.
The three basic particles of the atom are:
protons,
neutrons, and
electrons.
The central portion of the atom is the nucleus.
The nucleus consists of protons and neutrons.
Electrons orbit the nucleus.

5. Number of Neutrons = A - Z
Notations
AZ X
A = Atomic Mass (number of protons or electrons plus number of neutrons)
Z= Atomic Number (number of Protons) or (number of Electrons in an electrically neutral atom)
Number of Neutrons = A - Z

6. Notations 3 T or H-3 or H 1 238 U-238 or U 92
Tritium is designated as:
T or H-3 or H
238 92
Uranium (238) is designated as:
U-238 or U 3 1

7. What are Isotopes ?
They are not just a sports
team on the Simpsons.

8. The Isotopes
Atoms which have the same number of protons but different numbers of neutrons are called isotopes.
Isotopes of Carbon.

9. The Isotopes. ISOTOPES of hydrogen
Protium H
Deuterium D
Tritium T
No neutrons
1 neutron
2 neutrons H D T n
The different isotopes of an atom are chemically identical. The above isotopes of hydrogen all act chemically the same.

10. What is Radioactivity ?
If there are too many or too few neutrons for a given number of protons, the nucleus will not be stable.
The unstable atom will try to become stable by giving off excess energy. This energy is in the form of particles or rays (radiation). These unstable atoms are known as radioactive atoms, or radioactive materials.

11. How do unstable Isotopes become stable?

12. By Radioactive decay
Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide.

13. How long does Radioactive decay take?
Half life it’s more than just a game.

14. Radioactive half-life
The radioactive half-life for a given radioisotope is the time for half the radioactive nuclei in any sample to undergo radioactive decay.
After one half-life, there will be one half the activity of the original sample. After two half-lives, there will be one fourth the activity of the original sample, after three half-lives one eighth the activity of the original sample, and so forth.

15. Radioactive Decay is an Exponential Process
The activity at time (t) is related to the initial activity at time (0)

16. To determine the activity present after time (t)
You need to know
1. The initial activity of the isotope involved.
(Activity at time “0” or Ao)
2. The half life of the radioactive isotope.
(T1/2)
3. The time after the initial activity was determined.
(DT after the determination at time “0”)

17. Example You have 10 mCi of P-32 on January 1, 2008.
How much activity will you have on January 29, 2008?
Given: The half life of P-32 is 14.3 days.

18. Solution Example: Decay of 32P in time Known: 1. Ao = 10 mCi
2. T1/2 = 14.3 days
3. Time after initial activity (t) = 28 days
Using A (t) = Ao e-lt
= 10 e –(0.693/14.3)(28)
= 2.57 mCi

19. Radioactivity may be defined as:
Spontaneous nuclear
transformation

20. Non-ionizing vs. Ionizing radiation
Non-ionizing radiation refers to any type of electromagnetic radiation that does not carry enough energy per quantum to ionize atoms or molecules — that is, to completely remove an electron from an atom or molecule.
Examples of non-ionizing radiation: microwaves, ultraviolet light, lasers, radio waves, infrared light, and radar.

21. Ionizing radiation consists of subatomic particles or electromagnetic waves that are energetic enough to detach electrons from atoms or molecules, ionizing them.
Examples of ionizing radiation: alpha particles, beta particles, neutrons, gamma rays, and x-rays.

23. Ionization
Ionization is the process of removing electrons from neutral atoms.
It is important to note that exposure to ionizing radiation, without exposure to radioactive material, will not result in contamination of the worker.

24. Two general categories of ionizing radiation:
PARTICLES
alpha
neutron
beta
PHOTONS
X-ray
gamma ray

25. Radiation Fundamentals
The Four Basic Types of Ionizing Radiation
alpha particles,
beta particles,
gamma or X rays,
neutrons.

26. Alpha Particles
Physical Characteristics: Large mass, highly charged, helium nuclei (2 protons, 2 neutrons)
Range: 1-2 inches in air
Shielding: Dead layer of skin, paper.
Biological Hazards: Internal, it can deposit large amounts of energy in a small amount of body tissue.

27. Alpha Particles Alpha particles are highly energetic helium nuclei p+
cannot get
through skin
stopped
by paper
internal
hazard
soil, radon, and heavy
man-made elements

28. Beta Particles Physical Characteristics: Small mass, electron size,
Range: Short distance (one inch to 20 feet).
Shielding: Plastic
Biological Hazard: Internal hazard. Externally, may be hazardous to skin and eyes.

29. Beta Particles Beta particle: an energetic electron
from an unstable nucleus
skin, eye, and
internal hazard
stopped
by plastic
natural food, water, air

30. Gamma Rays/X-Rays
Physical Characteristics: No mass. No charge. Electromagnetic wave or photon.
Range: Very far. It will easily go several hundred feet. Very high penetrating power.
Shielding: Concrete. Water. Lead.
Biological Hazard: Whole body exposure. The hazard may be external and/or internal. This depends on whether the source is inside or outside the body.

31. Gamma Rays/X-Rays Gamma and X-rays are photons
(massless electromagnetic energy)
stopped by
dense shielding
naturally present
in soil and in
cosmic radiation
medical,
radioactive
materials

32. Neutrons Physical Characteristics: Fairly large. No charge. Has mass.
Range: Range in air is very far. Easily can go several hundred feet. High penetrating power due to lack of charge (difficult to stop).
Shielding: Water. Concrete. Plastic (high hydrogen content).
Biological Hazard: External whole body exposure.

33. SUMMARY of External and Internal Hazards
Alpha
Minimum
Severe
Beta
Higher than Alpha
Less severe than Alpha
X-ray and Gamma
Less severe than Alpha, Beta
Neutron
Not considered

34. Review. The three basic particles of an atom are,
protons,
neutrons, and
electrons.
Radiation is energy in the form of particles or rays given off by unstable atoms.
The half-life for a given radioisotope is the time for half the radioactive nuclei in any sample to undergo radioactive decay.

35. Review cont.
Ionizing radiation consists of radiation energetic enough to detach electrons from atoms or molecules, ionizing them.
Non-ionizing radiation refers to any type of electromagnetic radiation that does not carry enough energy to completely remove an electron from an atom or molecule.

36. Review cont.
The four basic types of ionizing radiation are: alpha particles, beta particles, gamma or X rays, neutrons.
Alpha particles, Large mass, highly charged,
Range: 1-2 inches in air,
Shielding: Dead layer of skin, paper.
Biological Hazards: Internal
Beta particles, Small mass,
Range: one inch to 20 feet.
Shielding: Plastic.
Biological Hazard: Internal hazard. Externally, may be hazardous to skin and eyes.

37. Review cont. The four basic types of ionizing radiation cont:
Gamma or X rays, No mass. No charge.
Range: It will easily go several hundred feet. Very high penetrating power.
Shielding: Concrete. Water. Lead.
Biological Hazard: External whole body exposure.
Neutrons, Fairly large. No charge. Has mass.
Range: Easily can go several hundred feet. High penetrating power due to lack of charge.
Shielding: Water. Concrete. Plastic (high hydrogen content).

38. Test Time! Follow this link to the test. https://myresearch.wsu.edu
Use your WSU user name and password to sign in.
Click on the training tab.
Then click on the available training tab
Find the basic radiation physics course, in the OR section, click on it and take the test.