{HEAD ~ This modified accelerator} has {TAIL ~ a narrow sharp space distribution} of emitted x ray radiation even for a low energy x ray beam 
has
{ HEAD ~ This modified accelerator } has { TAIL ~ a narrow sharp space distribution } of emitted x ray radiation even for a low energy x ray beam
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH