Absorption of gamma rays experiment (opinions?)

[don1231915]

Hey
I recently did an experiment on the absorption of gamma rays
I calculated the thickness and the no. of counts, got a nice exponential curve.
So, I used lead as the absorbent or shielding material for gamma...
Any suggestions what else I can use for gamma?

I thought about sausages or water or a stone maybe? Is that a good idea.
However, I have no idea how I would calculate the thickness of stones or water?

Please advice me on this!


THANK YOU SO MUCH!

 

[Bob S]

Aluminum or copper would be a good choice if you could find enough. Look at the table of material properties in

http://pdg.lbl.gov/2009/reviews/rpp2009-rev-atomic-nuclear-prop.pdf

especially the column labeled Rad length (radiation length), which is the 1/e penetration length for high energy gamma rays and electrons. Note at bottom of page the radiation length of water and other materials is given. The penetration in water is about 5.6 times more per gram per cm².** Also see the NIST attenuation table for elements:

http://physics.nist.gov/PhysRefData/XrayMassCoef/tab3.html

Gamma ray attenuation is primarily by Compton scattering and deep core photoejection (photoelectric effect). Low Z materials like aluminum have very little deep core photoejection relative to lead.

Your attenuation measurements will depend on whether you are measuring just the unscattered incident photons, or all the transmitted photons including Compton scattered photons.

**[added] At gamma ray energies near 1 MeV, the gamma ray absorption length is inversely proportional to the density of electrons per cubic cm.

Bob S