Two Radioactive Substances from Magnesium after Deuteron Bombardment

Under bombardment by 3.3 MEV deuterons, magnesium becomes radioactive with the emission of negative electrons and gamma-rays, and with two decay periods: 10{}±{}{} min. and 15.8±{}0.5 hours. These periods are characteristic of Mg²⁷ (Fermi) and Na²⁴ (Lawrence). The reactions producing these bodies are: ${₁₂Mg²⁶+₁H²,=₁₂Mg²⁷+₁H¹; ₁₂Mg²⁷=₁₃Al²⁷+{β}+{γ}.}{₁₂Mg²⁶+₁H²,=₁₁Na²⁴+₂He⁴; ₁₁Na²⁴=₁₂Mg²⁴+{β}+{γ}.}$ The protons have not been looked for. The alpha-particles have a range of about 7 cm. The ${Mg}²⁷$ beta-rays have 2.0 MEV maximum energy, and the accompanying hard gamma-ray has about 1.3 MEV energy. The voltage excitation functions of these two activities have been measured, and have been found to follow different laws. The Mg²⁷ following the Oppenheimer and Phillips function and the Na²⁴ the older Gamow function. At 3 MEV one atom becomes Na²⁴ for each 9.6 atoms going to Mg²⁷. The thick target yield of Mg²⁷ atoms is about 5 per 10⁷ deuterons. The nuclear cross section (Mg²⁶) at 3 MEV is about 2.4×{}10^-26.