Beam 07 : A flow of electromagnetic or particulate radiation that is either unidirectional by nature, or has been collimated or restricted to a small solid angle
Jefferson Lab, Radiation Worker Glossary, Newport News, VA, USA 2007. http://www.jlab.org/div_dept/train/rad_guide/gloss ary.html, (Rad Sfty, Prot and Cont - Amer) {1005}