method of estimating and subtracting the hydrogen background in the natural carbon target used in the ¹²C + ¹²C experiment

he experimental data of 100A MeV 12C + 12C elastic scattering are checked by using two-body kinematic calculation and 12C+p elastic scattering. It is shown that the measured data are true and reliable. In the paper, the transformation between the excited energy spectra of the 12C+12C system and the ground state energy spectra of the 12C+p system is introduced. The method of subtraction of the hydrogen background in the natural carbon target used in the experiment is elaborately described and the results are discussed. It is indicated that this method of subtraction of hydrogen background is reasonable and can be used in the data analysis. Based on the elastic scattering cross section of the previous experiment of 12C+p at 95.3A MeV, the hydrogen content entered into the reaction is analyzed. The final hydrogen content in the natural carbon target is (2.73 ± 0.12)%.