Radioactive Decay

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Radioactive Decay

• Cindy So

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Curvebank Project

• Website with many mathematical curves
• Information on curves
• Animation of curve
• http//curvebank.calstatela.edu/home/home.htm

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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

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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

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Carbon-14 dating chart
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Earths 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

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General Equation

• Exponential decay
• A Aoekt
• Calculations with potassium-argon dating
• A Aoekt
• 0.945 1 e(-5.29x10-10)t
• ln(0.945) (-5.29x10-10)t
• t 107 million years

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Half-life

• Referred using half-lifes
• Time for radioactive substance to decay by half
• Calculation using carbon-14
• A Aoekt
• 0.5 1 e(-0.000121)t
• ln(0.5) (-0.000121) t
• T 5728 years

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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

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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)

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Calculations

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

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Calculations

• new.x Ax C
• new.y By D
• C window.left A graph.left
• D window.bottom B graph.bottom

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Mapping points
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Mapping points

• 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

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Check figures

• new.x 180x 40
• new.y 240y 60
• (2,1) ? (400,300)
• (0,0) ? (40,60)

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JAR files

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

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Benefits of JAR

• Security
• Decreased download time
• Compression
• Packaging for extensions
• Package Sealing
• Package Versioning
• Portability

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Creating JAR files

• jar cf jar-file input-file(s)
• jar tf jar-file
• ltapplet codeAppletClassName.class
  archive"JarFileName.jar" widthwidth
  heightheightgt lt/appletgt

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Demo

• http//curvebank.calstatela.edu/radiodecay/radiode
  cay.htm

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The End