A wire position monitor (wpm) system to control the cold mass movements inside the TTF Cryomodule

A system able to measure, on-line, movements and vibrations of the cold mass (CM) during cool down and steady state operation has been developed and installed inside the first TTF Cryomodule. The system includes two independent lines, with 18 WPMs each, and an improved version of BPM type. Laboratory tests on a shorter prototype have shown that the system is able to monitor the CM displacements with a few micron sensitivity, the absolute error being less than 50 microns in the range of /spl plusmn/2.5 mm. Fast read out and an FFT technique allow also to detect and analyze possible CM vibrations.