Spallation of Aluminum by 28-GeV Protons

In the bombardment of Al foils with 28-GeV protons the following cross sections (in mb) for production of the indicated nuclides were obtained: Be⁷, 7.9±{}0.5; F¹⁸, 6.0±{}0.3; C¹¹, 4.7±{}0.2; Na²², 9.8±{}0.6; N¹³, 1.18±{}0.07; Na²⁴, 8.3±{}0.5; O¹⁵, 3.5±{}1.0; Mg²⁷, 0.067±{}0.006. An upper limit for the Ne²⁴ cross section of 0.6 mb was obtained. The Mg²⁷ cross section has been corrected for secondary reactions and represents only production by primary protons, presumably by the (p, pπ⁺) reaction. The measurements were made relative to the production of C¹¹ activity in polyethylene and polystyrene foils. The production of Be⁷ in the plastic foils was also observed and corresponds to a cross section of 7.7±{}0.4 mb per carbon nucleus. By comparison of these cross sections with those at lower bombarding energies, no significant trend of the excitation functions is observable.