The photodisintegration of ¹³C through excited states ¹²C and ¹²B

Gamma ray spectra from the reactions ¹³C( gamma ,n gamma ') and ¹³C( gamma ,p gamma ') have been measured simultaneously in a Ge(Li) detector at 112 degrees using bremsstrahlung with end-point energies in the range 15-44 MeV in order to study the decay of the ¹³C giant resonance through excited states of the residual nuclei. The cross sections for neutron emission to the 4.44 and 15.1 MeV states in ¹²C and for proton emission to the 0.95 MeV state in ¹²B have been measured. The integrated ¹³C( gamma ,2n) cross section up to 40 MeV has been determined and found to be very small in comparison with the ( gamma ,n) cross section. The ( gamma ,n) and ( gamma ,p) cross sections for feeding the ground states and also certain excited states which do not decay by gamma emission have been deduced. The cross sections are compared with other measurements and theoretical calculations. The structure of the ¹³C giant resonance is discussed. The results support the evidence for isospin splitting of the giant resonance as predicted in a number of theoretical calculations.