Last week we removed the silicon witness samples for dust particle contamination monitoring placed on ESQB1 (Figure 1) during early November (Logbook Entry 49870); unfortunately, the horizontal wafer placed in the center of the bench is broken (Figure 2), so there are 4 wafers that will be analyzed with the camera system in ISO 3 Perugia Clean Room.

We placed 5 new samples, approximately as in the same positions as the previous ones (Figure 3):

- On top of AEI squeezer box, horizontal
- On ESB1 bench, near AEI squeezer box, horizontal
- On ESB1 bench, near AEI squeezer box, vertical
- On ESB1 bench, approximately in the middle of the rectangular part of ESQB1, horizontal
- On ESB1 bench, approximately in the middle of the rectangular part of ESQB1, vertical

In addition, we placed a horizontal wafer inside the external Detection Room, on top of threshold of tower structure, behind detection bench minitower (Figure 4)

Horizontal witness samples have been left in their open boxes, vertical witness samples have been mounted on a vertical support with two screws.
Each sample has the clean face exposed and the box lid facing down next to it (ready to be closed and transported away).
Two additional wafers (one horizontal and one vertical) have been left exposed on the bench for 1' and removed, in order to monitor the dust fallout due to handling.

Please do not move the samples and report any activity that may need to be performed in the close proximity of a sample and may compromise its representativity of the average cleanliness condition of its location.