1. May 20, 2007

Im doing some Coursework in for... tomorow :S I know my own fault! but Ive only just come across the Problem and Ive been doing it for the last few Days.
Im designing an experiment Investigating the effect of Thickness of Aluminium against the Rate of Beta Particles passing through, so that people can find how thick it is based on the rate. Ive desiged most of it, just a few queries but quite important ones!

-Im wondering what a graph of Thickness/Rate would actually look like... Exponential or Linear? I think it would be a negative linear gradient decreasing rate against increasing thickness.

-Should I be plotting a lg Thickness/lg Rate? and what effect on the graph does plotting logs do? why do you do it? Ive come across Gravity/Distance from Centre which is Exp. Graph but log one was linear which may give me a better graph for calibrating the thickness against rate as i need a calibration graph so people can measure thickness with the rate.

-Finally, I know that Radioactivity decays with time... i do know something! heh. Should i be using a radioactive material with a long half life so the Rate of Beta Particles will not differ over time, OR does the rate stay the same?
Ive found Iodine 113 which i consider a perticularly safe material because its used in hospitals ect. and only 8day half life. but i figure activity will be changing every day so it needs to be callibrated almost every day to get accurate readings! not good! so i figured i need a fairly long half life (100's Years) so that the rate chages a little.

Sorry About My Bad Communicationaly Skills! Hope You can Help me! Ask be if Nothing makes Sense!

2. May 20, 2007

### malawi_glenn

Bethes formula : stopping power, familiar? [there are tow of them, one for heavy charged, and one for electrons]

Also with increasing life time, you will not get so many Beta particles / time.. otherwise you need a big samle. Say that you want 1000 decays / second, then you can calculate how much you need of every element if you know the elements half life.

Last edited: May 20, 2007
3. May 20, 2007