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I want to calculate the Radiation length in a Molecule with the Formula given on wikipedia. How do I calculate Z and A for a molecule to put it into the Formula?

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I'll see if I can find something on this in my books at home if no one else has answered it by then. If you just want to know pair production rates and such, you can use XCOM (, but I'm not sure how to incorporate the bremsstrahlung... – AdamRedwine Jul 25 '12 at 12:11
I am learning for an exam and I noticed that I did not calculate A and Z correctly on an exercise sheet. The right answer for Water (H2O) is Z = 7,5 and A = 12,5 but I do not really know how to get there. – miceterminator Jul 25 '12 at 12:18
In that case, check your textbook index for "effective atomic number." – AdamRedwine Jul 25 '12 at 13:46
Thanks I believe that is what I am looking for. – miceterminator Jul 25 '12 at 15:59
Better than the wikipedia is to go the the Particle Data Group for such calculation. You want the Chapter of the Review of Particle Physics on the "Passage of Particles Through Matter" – dmckee Jul 25 '12 at 15:59

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