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<br /> <br />III. FACILITIES AND EQUIPMENT <br /> <br />~~") <br />..;. . <br /> <br />}"\ <br />I <br />! <br /> <br />I <br />;"-, <br />'-',..-' ' <br />_.....":) <br /> <br />.. <br /> <br />.. <br /> <br />,TIVE <br />P~T <br />T'''-.' ... <br /> <br />~ ", <br /> <br />. L _ ... <br /> <br />..j <br />. I <br />,!\ ! <br />" <br />:j <br />, ' <br />" <br />! i <br />i' <br />i 1 <br />, I <br />, t " <br />..,.. ,I ',;' <br /> <br />'\ ,If IlIl <br />!.J Pi <br />}---.... .-- <br />..~ ~. ! <br />. i <br />L .~,~......__:1 <br /> <br />. <br /> <br />, '..' <br /> <br />r... <br /> <br />._ LAV <br /> <br />15 <br /> <br /> <br /> <br /> <br /> <br />Figure 17.-Typical Record from ZnS Airborne Detector Equipment. <br /> <br /> <br />Figure IS.-Laboratory ZnS Analyzer. <br /> <br />Background concentrations of Ag in snowmelt <br />samples and in snowcrystal replicas have been de- <br />termined in Phase I by the neutron activation an- <br />alysis technique. The actual analysis work was sub- <br />contracted since that was the least costly and fastest <br />method of getting results. Initial samples were <br />analyzed by the Hanford AEC facility as part of <br />one of their own programs; later analysis work was <br />done by Union Carbide Corp., Nuclear Products <br />Department, Tuxedo, N.Y. Activation analysis con- <br />sists of forming an isotope of a particular element <br />by bombarding a sample with the proper nuclear <br />particle. The distribution of energy levels in the <br />resultant isotopic radiation is then determined and <br />is directly convertible to mass. Detection threshold <br />with present methods is of the order of 10 picograms <br />(lOx 10-12 grams) . <br />Freezing nuclei count is monitored by a Bigg- <br />Warner expansion chamber device at Valley View <br />