As part of the effort to characterize stray light due to dust particle contamination (especially in the SQZ subsystem), on Thursday, June 11 we placed a series of silicon witness samples (kindly provided by Antonio P) in several positions around the DetLab and the AEI squeezer box. In particular:

• ESQB table, inside plexiglass box, space between the FI train and the telescope: one 2" and one 3" wafers placed horizontally, plus one 2" wafer in vertical
• ESQB table, on top of plexiglass box: one 3" horizontal
• Next to particle counter: one 3" horizontal
• On top of external detection bench: one 3" horizontal
• On top of threshold of tower structure, behind detection bench minitower: one 3" horizontal

Each witness sample, with the exception of the vertical one, has been left in its (open) box, clean face exposed, with its box lid facing down next to it (ready to be closed and transported away). The idea is to remove and analyze them in about 1 month time (with the exeption of one or two control samples to be removed earlier).

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.

Attached PDF shows more precisely the location of the samples.