The material of construction of the grid walls of this invention is glass with a high content of {HEAD ~ lead oxide}, or {TAIL ~ other high atomic number oxide} 
The material of construction of the grid walls of this invention is glass with a high content of { HEAD ~ lead oxide } , or { TAIL ~ other high atomic number oxide }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL