We observe a continuous horizontal beam drift in SA1 after the M1 incident. It seems not to converge, so one can wonder where this will go....
Attached screenshot shows the M2 piezo actuator RY that keeps the beam at the same position on the M3 PBLM. These are about 130 m apart, The drift is 1V/12 hours. 0.01V corresponds to a beam motion by 35 um. So the drift velocity is 0.3 mm/hour. In the past days this had at least once lead to strong leakage around M2. But the two feedbacks in the FXE path are keeping the beam usable most of the time. |