# Energy limits of gamma rays

1. Aug 15, 2007

### dtsormpa

Hello you guys. I was wondering about the energy limits of the gamma rays. I allready know that the gamma ray spectrum varies from some MeV to 50 MeV (approximately). Does anyone know how can these limits be justified?

2. Aug 15, 2007

### mathman

The lower limit of gamma ray energy is basically a matter of definition. X-rays are the next lower type and the boundary is somewhat arbitrary One way of defining might be when coherent scattering (X-ray) is more important than Compton (gamma).

There is no defined upper limit. It is merely a question of what is physically possible.

3. Aug 15, 2007

### chroot

Staff Emeritus
The distinction betwen hard X-rays and gamma rays is usually taken be their origin. Gamma rays are generated by nuclear decays, while hard X-rays are produced by man-made electronics.

There is no upper limit on gamma-ray energy, though the GZK cutoff is a limit on the energy of gamma rays which are able to survive long travels across the universe.

- Warren