The discrimination of {TAIL ~ an anomaly} of gas composition of {HEAD ~ the laser gas} can be accomplished by simple means 
The discrimination of { TAIL ~ an anomaly } of gas composition of { HEAD ~ the laser gas } can be accomplished by simple means
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH