This morning whilst I was setting up the ribbon cabling (see eLog entry #8) I was considering collecting a voltage bias vs leakage current curve for one/two of the S2 detectors, depending on time available.

This would involve using the central section of the chamber and the straight spacer box to mount the preamp on top of the lid.

Note: we currently cannot use the angled spacer boxes for the chamber yet, because these need to be trimmed by Antonio (the technician) to allow more space for the ribbon cables and also allow the box to sit flat on top of the vacuum feedthrough. We will be seeing Antonio on monday morning to prioritise required machine work.

However, I then remembered that after we stopped the pumps last night we did not vent the chamber. This morning at 10:52 the labview program used to control the pumps read the following pressures:

• Turbo Up 1 = 1000mBar
• Turbo Up 2 = 389mBar
• Turbo Down 1 = 86.1mBar
• Turbo Down 2 = 49.7mBar
• Chamber Up = 1000mBar
• Chamber Down = 139mBar

I emailed Lucio to see if he could come in this weekend to vent the chamber and we could then mount and test two of the S2 detectors, one after the other. Otherwise we can do this monday morning.

As an aside there is some serendipity here, the pressures I read this morning indicate if there is a leak in the chamber it is more likely to be found upstream.