[Kenta, Alex, Washimi, Yokozawan, Carl]
We would like to improve jitter coupling projections. Previously the mode cleaner was used to excite jitter 40-200Hz and IMMT2 trans QPDs were used as witness sensors to project that jitter noise to DARM. The mode cleaner was only excied in one degree of freedom, exciting MCE. We had tried but failed to excite the other degree of freedom (with MCI and MCO). The shaker tests might indicate jitter noise can be excited on the PSL table. We therefore planned today to excite angle at mirror M17 on the PSL table with a linear combination of IMC PZT1 and PZT2 to see if we find the same coupling function as the shaker test noise projection around 210Hz. We found that PZT1 was saturated and that QPDA1 was very noisey so wee did not make the measurement exactly as planned. The PZT needs manual ofloading, we will do that tomorrow. QPDA1 glitches seem to comer fom the piezo in the centerring loop on the QPD. When the loop is opened the glitches stop (but the low frequency beam position noise increases). We made a measurement in PZT2 pitch that can be used for noise projection. One a swept sin measurement and another a broadband measurement focussingon the 210Hz coupling frequency (attached). Projectionswill be processed tomorrow.
