Question

How to detect Gamma rays ?

Answer 1

You can use a gamma ray detector which can see a wider range of frequencies than the eye.

Answer 2

http://imagine.gsfc.nasa.gov/science/toolbox/gamma_detectors2.html

Answer 3

We can use the ionization chamber. Using an ionization chamber, gamma rays are detected by photoelectrons, Compton electrons or electron-positron pairs, which are produced by such incoming gamma rays.