Accelerator dosimetry at free electron lasers in Hamburg

Abstract: On 27 April 2006 a vacuum ultra violet free electron laser (FEL) named free electron laser in Hamburg (FLASH) producing intense beams of 13.1nm laser light became operational. A 260m long, 1GeV superconducting electron linear accelerator (linac) drives the FLASH. The electron linac is made of an array of superconducting niobium cavities developed at DESY on TESLA technology. During the FEL operation a parasitic radiation field of photoneutrons and bremsstrahlung gamma rays persists in the linac containment tunnel. Sophisticated measurement and control devices, based on radiation-sensitive commercial off the shelf (COTS) microelectronic components, have been installed near the FLASH linac. Therefore, it becomes necessary to characterise these stray radiations, in order to predict the radiation effects on electronics. This paper summarises the features of novel radiation dosimeters and accelerator dosimetry techniques developed by our group. The utilisation of valuable radiation dosimetry data gathered from the experiments at FLASH to predict the radiation field characteristics of the future European X-ray free electron laser (XFEL) driven by a 20GeV superconducting electron linac is highlighted. [Copyright &y& Elsevier]