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