Measurements ofBe10andAl26production cross sections with 12 GeV protons by accelerator mass spectrometry

The formation cross sections of ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$ and ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$ from Al, Fe, Co, Ni, Cu, Zn, Ag, and Au targets irradiated with 12 GeV protons were measured by accelerator mass spectrometry. The obtained cross sections were consistent with the excitation functions predicted from the literature values measured at other proton energies within the experimental uncertainties. The ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$ cross sections increased with an increase in the target mass. On the other hand, the ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$ cross sections decreased from Al to Ag targets, but increased somewhat from Ag to Au. The formation mechanisms of ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$ and ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$ including ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$, ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$, and ${}_{}{}^{24}{}_{}{}^{}\mathrm{Na}$ are discussed with respect to fitting of the experimental results to the calculated values using the universal formula of Campi et al. During the course of the discussion, we introduce a new parameter, the degree of neuton excess (N-Z)/A, in order to classify light fragments more clearly.