a CdS crystal annealed in an inert atmosphere at a temperature and for {HEAD ~ a period} of time to provide {TAIL ~ substantially maximum acoustic attenuation} at the operating frequency of the crystal; and 
to provide
a CdS crystal annealed in an inert atmosphere at a temperature and for { HEAD ~ a period } of time to provide { TAIL ~ substantially maximum acoustic attenuation } at the operating frequency of the crystal ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH