Tritium is {HEAD ~ a soft beta emitter} and {TAIL ~ the radiation} will not penetrate the glass wall of the envelope 
Tritium is { HEAD ~ a soft beta emitter } and { TAIL ~ the radiation } will not penetrate the glass wall of the envelope
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH