Radiation field inside the tunnel of the Linear Collider TESLA

Highly integrated electronic circuits are planned to be installed inside the tunnel of the TESLA collider. Life time und performance of complex control systems have to be investigated in a pulsed radiation field. First measurements around the cryo-modules of the TESLA Test Facility are presented indicating energy dose rate levels in the order of 1 Gy/h. Assuming a dynamic heat load of 0.1 W/m a dose rate of 10 mGy/h is predicted by a Monte-Carlo calculation. The comparison of the measured effective photon energy with the calculations shows that the radiation field mainly originates from accelerated dark current (electron energies above 20 MeV) rather than from onecell dark current (electron energies below 5 MeV).