On Tue, 23 May 2006, David VanHorn wrote: >> That is glass fluorescence. It is not caused by ionising radiation. > > Not glass, electrons passing through nitrogen that has leaked into the tube. However a nice pale lime green fluorescence in the body of the glass usually means X rays ;-) Peter -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist