{TAIL ~ luminescent target} means , for converting to {HEAD ~ luminescence values} the photoelectron emission from test points  
{ TAIL ~ luminescent target } means , for converting to { HEAD ~ luminescence values } the photoelectron emission from test points
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH