Radiation dosimetry in FLASH tunnel using passive dosimeters

Sophisticated electronic devices comprised of sensitive microelectronic components have been installed in the close proximity of the 720 MeV superconducting electron linear accelerator (linac) driving FLASH, the Free Electron Laser in Hamburg, presently in operation at DESY in Hamburg. Microelectronic chips are inherently vulnerable to ionising radiations, usually generated during routine operation of high-energy particle accelerator facilities like FLASH. Hence, in order to assess the radiation effect on microelectronic chips and to develop suitable mitigation strategy, it becomes imperative to characterise the radiation field in the FLASH environment. We have evaluated the neutron and gamma energy (spectra) and dose distributions at critical locations in the FLASH tunnel using superheated emulsion (bubble) detectors, GaAs light emitting diodes (LED), LiF-Thermoluminescence dosimeters (TLD) and radiochromic (Gafchromic EBT) films. This report highlights the application of the passive dosimeters for an accurate analysis of the radiation field in produced by high-energy electron linear accelerators. (orig.)