Quadrupole Vibration Measurements of a TESLA Type II Cryomodule

Results of a study of the mechanical and vibrational features of a TESLA type II cryomodule are presented. The transmission of the ground vibrations to the quadrupole of the so-called ‘Superstruktur’ has been measured at room temperature, in the frequency range from 0.1 to 250 Hz, using inertial sensors. No evidence for resonances of the quad package support structure has been found within the explored frequency range. A comparison with measurements performed at liquid Helium temperature on an operating cryomodule with similar design is presented. No change in the transfer function is evident in transition from warm to cold conditions. The TESLA cryomodule mechanical layout, with the quadrupole placed at the end of the module, supported by the Helium Gas Return Pipe (GRP), meets the ILC (International Linear Collider) stability requirements in terms of quadrupole vibration.