Absolute Cross Section Versus Energy of the ${\mathrm{Cu}}^{63}(\gamma , n)$ and ${\mathrm{Cu}}^{63}(\gamma , 2n)$ Reactions

Experimental values were found for the absolute cross section of both ${\mathrm{Cu}}^{63}(\gamma , n)$ and ($\gamma , 2n$) reactions versus quantum energy from threshold to 36 Mev. Statistical and systematic errors were limited by the use of (a) the direct electron beam of the Stanford 36-Mev linear accelerator, which produced bremsstrahlung immediately before and within the copper foils under bombardment, (b) an electron-beam collector which recorded the total accumulated charge in the incident flux, (c) a $4\pi$ scintillation counter which measured the activity of the resultant ${\mathrm{Cu}}^{62}$ and ${\mathrm{Cu}}^{61}$, and (d) electroplated foils of separated ${\mathrm{Cu}}^{63}$ isotope.