1. Radioactive Decay Cindy So

2. Curvebank Project Website with many mathematical curves Information on curves Animation of curve http://curvebank.calstatela.edu/home/ho me.htm http://curvebank.calstatela.edu/home/ho me.htm

3. What is Radioactive decay? Decay is occurs in the parent isotope creates a daughter isotope Decay to form a more stable atom Readjustment of neutrons and protons Random process Impossible to predict the decay of individual atoms

4. Why is it important? Used to determine dates of objects Uranium-lead dating Highly respected Error of dates of three billion years old is no more than two million years Potassium-argon dating Carbon-14 date more recent objects

5. Carbon-14 dating chart

6. Earth’s Age 4.55 billion years Compromise of two ages Zircon - oldest known minerals is about 4.404 billion years Ca-Al-rich inclusions – oldest known solid constituents within meteorites – are 4.567 billion years old

7. General Equation Exponential decay: A = A o e kt Calculations with potassium-argon dating A = A o e kt 0.945 = 1 e(-5.29x10 -10 )t ln(0.945) = (-5.29x10 -10 )t t = 107 million years

8. Half-life Referred using half-lifes Time for radioactive substance to decay by half Calculation using carbon-14 A = A o e kt 0.5 = 1 e (-0.000121)t ln(0.5) = (-0.000121) = t T = 5728 years

9. Types of decay Each radioactive isotope decay differently Carbon-14 has half-life of 5730 years Cobalt-60 has half-life of 0.7916 years Sodium-24 has half-life of 18 hours Krypton-81 has half-life of 13 seconds

10. Goal of project Main goal: graph the radioactive decay curve Information needed: Range of time (x-axis) Decay rate and its type Not needed Amount (y-axis)

11. Calculations Split time into 500 sections Used equation to calculate amount remaining Needed to adjust the graph points into the window screen

12. Calculations new.x = Ax + C new.y = By + D C = window.left – A * graph.left D = window.bottom – B * graph.bottom

13. Mapping points

14. A = (400-40) / (2-0) = 180 B = (300-60) / (1-0) = 240 C = 40 – (180 * 0) = 40 D = 60 – (240 * 0) = 60 new.x = 180x + 40 new.y = 240y + 60

15. Check figures new.x = 180x + 40 new.y = 240y + 60 (2,1)  (400,300) (0,0)  (40,60)

16. JAR files Java TM Archive (JAR) bundle multiple files into a single archive file. contains the class files and auxiliary resources associated with applets and applications.

17. Benefits of JAR Security Decreased download time Compression Packaging for extensions Package Sealing Package Versioning Portability

18. Creating JAR files jar cf jar-file input-file(s) jar tf jar-file

19. Demo http://curvebank.calstatela.edu/radiodeca y/radiodecay.htm

20. The End