Characterisation of the bremsstrahlung generated by a 450 MeV superconducting electron linac using the inverse calculation method based on a genetic algorithm

The bremsstrahlung energy spectrum generated by the 450 MeV electron linac driving the vacuum ultra violet free electron laser FLASH (free electron laser in Hamburg) operated by DESY was measured with TLD-700 detectors and unfolded using a technique based on a genetic algorithm. The half (1/2), one-fourth (1/4) and tenth (1/10) value layer thickness of lead were estimated to be 1.0, 4.0 and 20 mm, respectively. The peak and average photon energy were calculated from the unfolded bremsstrahlung spectrum and found to be 0.5 and 0.8 MeV, respectively.