ICE NEAR 0℃: RADIOLYSIS AND ABSORBED DOSE CALORIMETRY

摘要

The production of H_2O_2 vs absorbed dose was measured for deaerated ice and H_2-saturated ice at -23, -10 and -0.8℃. For the first time, the establishment of a steady state was demonstrated. The dose required to reach a steady state of 0.7-0.8 μmol·dm~(-3) H_2O_2 was about 20 Gy in clear, annealed crystals at -0.8 and -10℃. The steady state concentration of H_2O_2 was about 70% higher in annealed ice than in freshly-frozen ice. 200-400 Gy was needed to reach a steady state concentration of 1.2 μmol·dm~(-3) H_2O_3 in cracked crystals at -23℃. In H_2-saturated ice at -23, -10 and -0.8℃, H_2O_2 reached a steady state concentration of about 0.2 μmol·dm~(-3) at less than 8 Gy. Ice near 0℃, after pre-irradiation to a steady state, has a heat defect of zero which is a useful condition for ice calorimetry.