i need information about radiation detection and detectors?

Answer 1

There are many types of radiation; many are particles for which see:
http://en.wikipedia.org/wiki/Particle_detector

For electromagnetic radiation (gamma rays, infrared) see:
http://en.wikipedia.org/wiki/Radiometer
http://en.wikipedia.org/wiki/Infrared_detector
http://en.wikipedia.org/wiki/Gamma_ray

Answer 2

Essentially there are three kinds of radiation to be detected, Alpha , Beta and gamma rays. The hardest to detect is alpha the easiest is Gamma