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