# Gamma ray experiment

#### Liquidxlax

1. Homework Statement

In my honours lab we had to perform the Gamma ray experiment in which we have to measure the operating voltage of a Geiger Muller tube for a radio active source say Cs-137.

With this we want to measure the linear absorption coefficients of lead and aluminium. Test the 1/r2 dependance. We wanted to also perform computer analysis in which we did counts over certain intervals for a number of counts and of course measure the dead time of our Geiger tube.

When writing the report we have to discuss the history of this experiment and the theory it is based on. Unfortunately i'm not to sure on the theory behind it, when we're given the equipment and are told to figure it out ;(

I'm guessing this experiment is partially based on the Compton effect, because gamma rays that do not scatter in the right direction obviously will not reach the geiger tube.

Some insight would be great.

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#### daveb

When you say theory behind the experiment, you mean the exponential attenuation through the material, the 1/r2 dependence of the flux, the electronics of the GM tube, counting statistics, or what (or maybe all) - these are all different ideas.

#### Liquidxlax

When you say theory behind the experiment, you mean the exponential attenuation through the material, the 1/r2 dependence of the flux, the electronics of the GM tube, counting statistics, or what (or maybe all) - these are all different ideas.
mostly the exponential attenuation through the material, and why it occurs, I know how the geiger tube works, why the 1/r^2 dependance is.

#### daveb

Wikepedia has a good discussion of the http://en.wikipedia.org/wiki/Beer%E2%80%93Lambert_law" [Broken] which is the mathematical basis for attenuation.

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#### Liquidxlax

Wikepedia has a good discussion of the http://en.wikipedia.org/wiki/Beer%E2%80%93Lambert_law" [Broken] which is the mathematical basis for attenuation.
thanks i'll look into it

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