1. Mary Lou Dunzik-Gougar, Ph.D.
Radiation Basics
Mary Lou Dunzik-Gougar, Ph.D.
Idaho State University /
Idaho National Laboratory
Candace C. Davison, M.S.
Pennsylvania State University
Radiation Science and Engineering Center

2. What do the following things have in common?

3. Doctor

4. Voyager

5. Soda Can

6. Bugs

7. Each represents an application of nuclear science and technology.

8. What we’ll cover . . . Atomic Basics What is Radiation? Types
Characteristics
Sources of Ionizing Radiation
Concepts
Radioactivity
Half-Life
Contamination vs. Irradiation
Terms

9. 100 Years of Nuclear Discovery

10. Atomic Structure of Helium
THE HELIUM’S subATOMIC
HELIUM ATOM COMPOSITION
2 Protons
2 Neutrons
2 Electrons e- p+ n n p+ e-

11. More on this helium isotope . . .
Protons have a large mass and a positive charge. The number of protons identifies an element.
MASS NUMBER
is the total number of
protons and neutrons 42 n
Neutrons have a large mass approximately equal to a proton’s mass. Neutrons have no charge. He
ELEMENT SYMBOL
Electrons have a very small mass and a negative charge. Electrons travel outside the nucleus. e-
ATOMIC NUMBER
is the number of protons

12. Transmission of energy via . . .
What is Radiation?
Transmission of energy via . . .
Particles or
Waves

13. Types of radiation Non-Ionizing Radiowaves Microwaves Infrared
Ultraviolet
Visible Light

14. Electromagnetic Spectrum

15. Types of radiation Non-Ionizing Radiowaves Microwaves Infrared
Ultraviolet
Visible Light
Ionizing
Alpha
Beta
Gamma
X-Rays
Neutrons

16. Why is it called ionizing?
Because it creates ions --atoms with a charge.
Ejected Electron
Ionizing
Radiation

17. Where does radiation come from?
Atoms . . .
from radioactive or unstable atoms

18. Hence, we have terms such as nuclear science/medicine/reactors.
What part of atoms?
The Nucleus
Hence, we have terms such as nuclear science/medicine/reactors.

19. What is radioactivity?
The spontaneous emission of “fragments” or “bundles” of energy from energetic nuclei creating more stable nuclei.
Radioactive atom
Energy and radiation released
More stable
atom formed

20. It’s called background radiation.
If radiation comes from atoms and everything is made of atoms, is there radiation around us right now?
You Betchya!
It’s called background radiation.

21. Sources of radiation The average American receives a
Source: National Council on Radiation Protection and Measurement Report 160 (2006)
The average
American receives a
radiation dose of 620 millirem per year.
Nuclear Power
(<0.1%)
Human Body
(5%)
Cosmic
Consumer Products
(2%)

22. Units of Dose and Exposure
Roentgen (R) - unit of exposure - ionization of air by x or gamma rays
RAD (Radiation Absorbed Dose) - energy deposited in material
rem - (Roengten Equivalent Man)
unit of dose equivalent

23. Perspective Dose (mrem) Source 1 Dental xray 25
Round trip flight to South Africa 40
Your body
110
Head and body CAT scan
620
Average dose in U.S.
5500
Average dose in Guarapari, Brazil
10,200
Average dose in Ramsar, Iran
0 – 25,000
No observable effect

24. Radiation Types Alpha () Beta () Gamma () 2 protons, 2 neutrons
Doubly positively charged particle n p+
Beta ()
Like an electron
Singly negatively or positively charged particle -
Gamma ()
Wave energy (not a particle)

25. PENETRATING ABILITY - + + g b a

26. SHIELDING
Concrete
alpha
beta
gamma
Lead
Wood
Paper

27. Radioactive Decay Equations
Alpha Decay
Beta Decay
Gamma Decay
238 92 U
234 90
Th + 4 2 a Th 91
Pa + -1 b
60m 56 Co 60
Co + g + n

28. dps - disintegrations per second
Units of “Activity”
Activity - a rate; the number of emissions (of radiation) per unit time.
dps - disintegrations per second
Bequerel = 1 dps
Curie = 37,000,000,000 dps
Picocurie = dps or 2.2 dpm

29. Half Life

30. Half Life

31. Radioactive Contamination
Radioactive Contamination - is radioactive material in an unwanted place.

32. Why are we concerned about Radiation?
Ionizing Radiation
Human Cells
Atoms in Cells Form Ions
Change in Cell
Cell Dies
No/Neutral
Not Replaced
Replaced
Reproduces
Malignant Growth
Benign Growth

33. How do we protect ourselves?
Time
Distance
Shielding

34. The End . . .