Determination of impurities by neutron activation analysis, (2). Determination of Ar in air, He and Cu by neutron activation analysis

Neutron activation analysis has been applied to the determination of argon in air, helium and copper metal. Air and helium samples were sealed in polyethylene tubes and irradiated simultaneously with argon standard in the JRR-1 reactor at a neutron flux of about 3 x 10¹¹n/cm²/sec for 20 min. After the irradiation, they were mounted in a 3 x 3 in. sodium iodide crystal attached to a RCL 256 channel pulse height analyzer. Argon was determined by the γ ray spectrometry, comparing the height of photopeak at 1.29 MeV γ of samples with that of standard. Argon in copper metal was determined by means of radiochemical separation and γ ray spectrometry. A copper sample was irradiated simultaneously with argon standard in the JRR-1 reactor for 2 hr. The irradiated sample was dissolved in diluted HNO₃ in helium atmosphere and argon was absorbed in a charcoal trap cooled with liquid nitrogen. Argon collected in the trap was determined by the γ ray spectrometry. (author)