Today we entered in IB tower. The scope of this intervention was to put the bench horizontal (around tx in the VRS) as planned in the actions that should be undertaken to cope with the vertical wedges of BS and POP (see VIR-0267A-15). In order to do it we have placed a very accurate water level on SIB1 bench (20 urad/div) as one can see on the first picture.

The level has been placed on the East side of the bench. In order to cope with the extra weight we have removed 1.5kg of our balacing weights. Then, Paolo could move SIB1 bench around tx to put the bench horizontal. On the second picture, we can see a view of the level when we were almost perfectly horizontal. The calibration of the local control system has been checked using the level and the error is lower than 10%.

In order to have the bench perfectly horizontal we had to tilt SIB1 bench by about 1.5 mard around tx (x is West-East direction).

East and west legs have been shifted by about 4mm towards east to cope with the 3.8 mm shift of SIB1 carried out yesterday (will be reported in a future logentry).

The bench blocking screws have been re-adjusted so that SIB1 bench can be blocked in a position close to the new reference position.

We have also unblocked the meniscus lens counter weight (located south side of the bench). It will be used in the future to compensate for unbalacing of the bench created by the meniscus lens longitudinal adjustment respect to PR mirror.

The tower will be closed tomorrow morning and the evacuation should start right after. From Friday, we will recover the bench alignment with SIB1 put horizontal.