Research is under way at SLAC to develop accelerator structure for a next generation linear collider. A full-scale prototype $X$-band structure has been built in which the dipole mode frequencies were detuned to suppress the long-range transverse wake field by about 2 orders of magnitude. To verify that the detuning works as expected, a facility, the Accelerator Structure Setup, was constructed in the SLAC Linear Collider to measure the long-range wake field. This Letter presents the results from the measurement of the prototype $X$-band structure with this facility.

• Received 9 November 1994

DOI:https://doi.org/10.1103/PhysRevLett.74.2475