Nuclear Excitation Functions. I.Na23(d,p)Na24,Br81(d,p)Br82, andBr(d,2n)Kr(34 hr.)

Abstract

Excitation functions for production of the radioactive isotopes ${\mathrm{Na}}^{24}$ (14.8 hr.), ${\mathrm{Br}}^{82}$ (34 hr.), and Kr (34 hr.) were obtained by bombardment of a stack of NaBr films obtained by evaporation in high vacuum onto aluminum foil. Deuteron energy determinations were made by measurement of range in aluminum; the maximum deuteron energy used in these experiments was 13.5 Mev. The activities of each isotope were measured on a calibrated gamma-ray counter which yielded three excitation curves and the absolute disintegration rates for the ${\mathrm{Na}}^{24}$ and the ${\mathrm{Br}}^{82}$ whose disintegration schemes are known. The reaction ${\mathrm{Br}}^{81}(d,p){\mathrm{Br}}^{82}$ exhibits an excitation function which begins at about 3 Mev, rises to a maximum absolute cross section of 3.8\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}25}$ ${\mathrm{cm}}^{2}$ at 8.5 Mev, and decreases with further increase in energy. The excitation of the reaction ${\mathrm{Na}}^{23}(d,p){\mathrm{Na}}^{24}$ shows the same shape but begins at about 1 Mev and reaches its maximum value of 4.7\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}25}$ ${\mathrm{cm}}^{2}$ at 6 Mev. The reaction $\mathrm{Br}(d,2n)\mathrm{Kr}$ shows a definite threshold at 5.3 Mev and rises almost linearly with increase in deuteron energy. Comparisons of these curves with the theory of Konopinski and Bethe indicate that the angular momentum with which the compound nucleus is formed is an important factor influencing the competition for the disruption of the compound nucleus.