TOPIC 1: HISTORY OF RADIATION

Explain the radiation and radioactivity and early pioneers in radioactivity

1. TOPIC 1: History of Radiation

2. Learning Objectives Explain radiation and radioactivity Explain early pioneers in radioactivity

3. RADIATION Radiation Energy in transit in the form of high speed particles and electromagnetic waves . Ionizing radiation -radiation with enough energy - during an interaction with an atom, it can remove electrons from orbital causing the atom to become charged or ionized -examples: gamma rays, neutrons Non-ionizing radiation -radiation without enough energy to remove electrons from atoms -Examples: visible light, radio and television waves, ultra violet (UV), and microwaves with a large spectrum of energies

4. Electromagnetic radiation Imaging employs electromagnetic radiation

5. l  (m)->  10-12  10-10  10-8  10-7  10-6  10-5  10-2  1                 gamma radiation  X-rays  far UV  UV  Visible  IR micro- wave  radio Nuclear events innner core electron high E outer elelctron outer electron low E outer electrons molecular vibrations molecular rotations transmitters

6. RADIOACTIVITY Radioactivity The spontaneous transformation of an unstable atom and often results in the emission of radiation Radioactive Material Any material that contains radioactive atoms. Radioactive Contamination Radioactive material distributed over some area, equipment or person

7. Before X-Rays were discovered Before X-ray were discovered… Rumor has said that an Italian Surgeon, Guido Lanfranc used to check for breaks in a skull by placing a string between patients teeth and plucking it out. If it made a musical note the skull was in tact. If was dim or of toned it showed a broken bone This could be very painful for patients. Think about somebody just squeezing your broken leg until they could find the place of the break When doctor’s diagnosed broken bones, tumors, and bullet locations it was all based on their best guess, and physical examinations

8. Science Park HS -- Honors Chemistry Roentgen: Discoverer of X-rays 1895 Becquerel: Discoverer of Radioactivity 1896 The Curies: Discoverers of Radium and Polonium 1900-1908 Rutherford: Discoverer Alpha and Beta rays 1897 Early Pioneers in Radioactivity

9. Brief Background (x-rays) Discovered accidentally by Wilhelm Conrad Röntgen in 1895 He discovered that these new invisible rays could pass through most objects that casted shadows including human tissue but not human bones and metals

10. How They Were Discovered Röntgen discovered the new ray while working with a cathode tube in his laboratory The tube was a glass bulb that had positive and negative electrodes inside When the air was removed from the tube, and a high voltage was applied it produced a florescent glow

11. VIDEO 1

12. How They Were Discovered He did not know what kind of rays were responsible for this phenomenon so he called them X-rays He made a phosphorescent screen and was shocked when he put his hand in front of the screen – he could see the outline of his bones Working with cathode ray tubes he noticed a phosphorescent material in his lab glowing several meters away

13. VIDEO 2

14. Discovery of Radioactivity Henri Becquerel French Physicist Brief Background (Radioactivity) He put different elements in the sun and placed them on photographic plates in dark drawers to study phosphorescence One day in 1896 there was no sun and he put Uranium on a photographic plate in a dark drawer. The next day the plate was cloudy! Energy was coming from Uranium itself

15. Marie and Pierre Curie Poland and France Brief Background (Radium & Polonium) Both died because they were exposed to radioactivity which caused toxicity in their body They discovered new radioactive elements Radium and Polonium in1898 Marie and Pierre Curie spent years purifying radioactive elements

16. Ernest Rutherford New Zealand Brief Background (Three types particle radiation) Rutherford found three different types of particles were emitted He called them alpha ( ) , beta( ) and gamma (γ) particles

17. First Reports of Injury Late 1896 Elihu Thomson - burns from deliberate exposure of a finger to X-rays Edison’s assistant - hair fell out & scalp became inflamed & ulcerated

18. Mihran Kassabian (1870-1910)

19. Chronology of early nuclear physics

20. 1895 - 1901

21. 1902 - 1908

22. 1909 - 1919

23. 1932 - 1938

24. 1939 - 1942