Yttrium Aluminium Garnet has a very fast response time of 50-60 ns and unlike plastic or most phosphor scintillators they do not degrade when bombarded by electrons or ions. They are very suitable for high current operations and have a very long lifetime. Light emission peaks about 560nm, response time below 5kV is better with YAG than for P47. The crystal should be coated with 50nm of aluminium before use. If the layer becomes damaged it can be removed with sodium hydroxide without damaging the surface of the