Physics.
a beam of particles of one kind selected from the group of particles produced when a beam of particles from an accelerator (primary beam) strikes a target.
Physics.
a beam of particles of one kind selected from the group of particles produced when a beam of particles from an accelerator (primary beam) strikes a target.
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012