Now for the Feature Presentation…

1. Silence is Golden Now for the Feature Presentation…

2. 3 1 2 NuclearR D TION Melissa Chan

3. Since Antoine Henri Becquerel’s accidental “stumble” onto the phosphorescent ability of uranium and Marie and Pierre Curie’s discovery and coining of the term “radio-active,” nuclear radiation has traveled a long way in its history of construction and destruction. It played an important role in World War II and the Cold War. Now, nuclear radiation pervades modern society, making its appearance in medicine, in nuclear electric plants, and in never-ending research. This is a journey to uncover its fundamental mechanics… Vy Dang

4. The Discovery of Radioactivity A. H. Becquerel 1896 • Natural radioactivity was first observed in 1896 by A. H. Becquerel, who discovered that when salts of uranium are in an unexposed photographic plate carefully protected from light, the plate becomes exposed. • the salts exhibit phosphorescence and are able to produce fluorescence. Since these effects are produced both by salts and by pure uranium, radioactivity must be a property Cindy T.

5. Marie and Pierre Curie 1898 • Won the Nobel Prize in 1903 for their research on the phenomena Marie named radioactivity. • Marie and Pierre Curie extended the work on radioactivity, demonstrating the radioactive properties of thorium. • Their work also led to the discovery of two new elements--polonium and radium in 1898. THE CURIES Cindy T.

6. Others who contributed... Frédéric and Irène Joliot-Curie discovered the first example of artificial radioactivity in 1934 by bombarding nonradioactive elements with alpha particles. In 1899 E. Rutherford discovered and named alpha and beta radiation, and in 1900 P. Villard identified gamma radiation. Frédéric and Irène Joliot-Curie Harriet Brooks Harriet Brooks' first real discovery came from working with radium, After studying and observing the emanation from radium, Brooks decided that it had to be a gas. Cindy T. E. Rutherford

7. Radioactivity Radioactivity refers to the phenomenon in which particles are emitted from the nucleus of an atom due to nuclear instability The products of radioactivity—alpha, beta, and gamma—were distinguished when scientists found that they could be separated by either a magnetic or electric field Vy Dang

8. Radioactive Elements Melissa Chan

9. Not all nuclei are stable; however, they will decay into a more stable atom. This radioactive decay is completely spontaneous. There are three ways that a nucleus can decay. It may give out : • an alpha particle (symbol a) • a beta particle (symbol b) • a gamma ray (symbol g) Melissa Chan

10. Radioactive Decay Equations Alpha Beta Gamma Mass Number E Atomic Number Element Symbol

11. Half-Life The one way to apply half-life is the explain the process of radioactive decay and its relationship to the concept of half-life. The primary intent is to demonstrate how the half-life of a radionuclide can be used in practical ways to "fingerprint" radioactive materials, to "date" organic materials, to estimate the age of the earth, and to optimize the medical benefits of radionuclide usage. Melissa Chan

12. Half-Life Calculations Definition: The length of time for half of a given number of atoms of a radioactive nuclide to decay Equations: n = Number of half life cycles = Time passed Half life of isotope Original amount(g) x 0.5n = Final remaining amount(g) Final amount (g) x 2n = Original amount (g) Vy Dang

13. Radiation Units Gray (Gy): One joule of energy per kilogram of tissue; absorbed dose Rad: Absorbed dose Becquerel (Bq): Measure of actual radioactivity in material; S.I. unit Curie (Ci): Activity of radioactive source Sievert (Sv): Takes into account biological effects of different types of radiation REM: Converted dose-equivalent from rads or grays; biologically effective dose Roentgens: Intensity of radiation source Dose Equivalent (DE): may be regarded as an expression of dose in terms of its biological effect. Conversions: 1 Bq = 1 disintegration per second (dps)1 Ci = 3.7 x 1010dps1 Ci = 3.7 x 1010Bq 1 gray = 100 rads1 sievert = 100 rem1 becquerel = 27 picocuries or 2.7 x 10-11 curies Vy Dang

14. Sources of Radiation Vy Dang

15. Two types of radiation: nonionizing and ionizing • Grays (Gy) measure the energy of radiation absorbed by the target in joules per kilogram. • Rems (Sv) measure dose quantity in joules per kilogram. • The Rems and Grays both measure the effect of radiation on the target, but the rem takes into account the effects of different types of radiation on human tissue. Jackie

16. Some forms of Exposure • Amount of exposure differs. • Sun’s ultraviolet rays • Water • Atmosphere • Electromagnetic fields • Nuclear bombs and reactors • Occupation Jackie

17. Nonionizing Radiation • The kind we are exposed to day-to-day (i.e. low-frequency electromagnetic fields) • Generally harmless • Electric appliances, power lines, radio/TV broadcasting, thunderstorms, radar, telecommunicates, light, etc. • Can pass through human bodies without apparent effects • Microwaves: high intensities can cause heating of tissue and burn injuries to skin • Ultraviolet: cause skin cancer • Cell phones: expose sensitive parts of the human body to radiation; try not to use often Jackie

18. The more dangerous type Where radioactive particles remove the valenceelectrons of the elements in living materials and changes the chemical reactivity of the affected atoms. Damages biological molecules (proteins/nucleic acids) and ruptures cell membranes. Ionizing Radiation Jackie

19. Biological Effects Jackie

20. Vy Dang

21. Geiger Counter Cindy Garza Invented from a German Physicist Hans Geiger.

22. Works by measuring the amount of ionization produced. Radiation particles enter the tube and turn into ions. Ions are electrically charged. Cindy Garza

23. The Geiger Counter Are: Nuclear Chemist nuclear power plants Teachers emergency services HAZMAT Homeland security EMT’s Golf ball companies. Cindy Garza

24. The detector uses americium- 241. It sends out a beam of neutrons in a straight line When smoke enter the detector the smoke breaks the line, and that’s when it rings. Cindy Garza

25. Conclusion… The present advancement in the understanding of nuclear radiation has been brought about by numerous people through years of research and experimentation. Its complexity is shown in the many units involved. This exploration has guided you through the fundamentals of nuclear radiation. It is now your turn to dive deeper into the areas specific to your interests. Perhaps one day your name will be written in the book of radioactive history… Vy Dang

26. The End

27. Works Cited Achey, Phillip M. ""Radiation Biology"" McGRAW-HILL ENCYCLOPEDIA OF Science & Technology. 9th ed. 15 vols. Chicago, IL: McGraw-Hill, 2002. Farndon, John . "The Curies." MAS Ultra - School Edition. 11/08/07 <http://search.ebscohost.com/login.aspx?direct=true&db=ulh&AN=9389372&site=src-live>. Harvey, Blatt. America's Environmental Report Card. Cambridge, MA: MIT P, 2005. Hicks, Jennifer. "Harriet Brooks: Working with Radioactivity ." Ebsco. 11/08/07 <http://search.ebscohost.com/login.aspx?direct=true&db=mih&AN=19998096&site=src-live>. "Images SI INC." Images SI INC. 2007 . Images SI, Inc. 12 Nov 2007 <http://www.imagesco.com/>. Lerner, K. Lee, and Lerner W. Brenda, eds. "Radioactive Fallout." The GALE ENCYCLOPEDIA of SCIENCE. 3rd ed. 5 vols. Detroit, MI: Thomson Gale, 2004. Lerner, K. Lee, and Lerner W. Brenda, eds. "Radioactive pollution." The GALE ENCYCLOPEDIA of SCIENCE. 3rd ed. 5 vols. Detroit, MI: Thomson Gale, 2004. Mitcham, Carl. "Radiation." Encyclopedia of Science Technology and Ethics. 3 vols. Detroit, MI: Thomson Gale, 2005. "Radioactive Smoke Alarms." Radioactive Smoke Alarms. December 1999. 12 Nov 2007 <http://www.ccsa.asn.au/nic/UraniumUse/Smokealarms.htm>. “Radioactivity ." Columbia Encyclopedia. 11/08/07 <http://search.ebscohost.com/login.aspx?direct=true&db=umh&AN=IXBradioact&site=src-live>. Settle, Frank. "The Biological Effects of Nuclear Radiation." Chemcases. 2005. National Science Foundation. 9 Nov. 2007 <http://www.chemcases.com/2003version/nuclear/nc-14.htm>. Vy Dang