Radioactive Decay

Cindy So

Curvebank Project

Website with many mathematical curves Information on curves Animation of curve

http://curvebank.calstatela.edu/home/home.htm

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

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

Carbon-14 dating chart

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

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

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) = tT = 5728 years

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

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)

Calculations

Split time into 500 sections Used equation to calculate amount

remaining Needed to adjust the graph points into

the window screen

Calculations new.x = Ax + C

new.y = By + D

C = window.left – A * graph.left

D = window.bottom – B * graph.bottom

leftgraphrightgraph

leftwindowrightwindowA

..

..

bottomgraphtopgraph

bottomwindowtopwindowB

..

..

Mapping points

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

Check figures

new.x = 180x + 40 new.y = 240y + 60

(2,1) (400,300)

(0,0) (40,60)

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.

Benefits of JAR

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

Creating JAR files

jar cf jar-file input-file(s) jar tf jar-file

<applet code=AppletClassName.class archive="JarFileName.jar" width=width height=height> </applet>

Demo

http://curvebank.calstatela.edu/radiodecay/radiodecay.htm

The End