Yesterday the realloaction of arm locking has been moved from NI/WI marionettes to NE/WE marionette. The test was partially successful: no issue concerning locking stability has been observed, so the strategy should work as it used to do in O3. An issue has been observed regarding the noise on Hrec: there was an increase around 30 Hz, mainly happening when NI and NE were swapped. We suppose it could be a worse cancelation of CARM SLOW noise, due to a not updated model of NE MAR actuator used by Hrec, Before doing a new test and eventually try to remain in low noise configuration, a CALIBRATION check is probably needed. In order to check that the actuators are working correclty, a noise injection has been performed in LN3 on both the NE MAR Z coils, and it has been compared to a simila injection on NI MAR Z. Apart from a difference in gain by about 20 %, nothing wrong has been observed. A coefficient in NE DSP has been updated in order to eliminate this difference, but the issue concerning the excess noise has not been fixed.

A second issue regards the possibility to act on NI/WI MAR relays and disconnect the DACs from the coils: the process serving this task seems to have disappeared. Without this action, the swap of actuators is useless. Experts have been informed.