Gamma absortion in atmosphere

[Gonzolo]

Hi, can someone tell me the extinction coefficient of a gamma ray in the atmosphere? How far does a gamma beam go in the atmosphere before its intensity reduces to half or to 1/e?

[mathman]

A long time ago, when I was working, I did calculations like this, but I can't remember the results. However, one thing that is very important is that it the distances you want are very strongly dependent on the gamma ray energy. 10 Mev rays go much further than 1 Mev rays.