On 20/11/2018:

At 9:00 we walked into the lab, David R reported he found all the pumps OFF. A thunderstorm occurred overnight causing a power outage.

Last night we had switched off the electronics (Preamp power, RAL amp rack, and NIM bin).

This morning we determined everything was ok to switch on.

Using eLog entries #26 and #27 as reference we mounted the following detectors and foils:

• Far S2: 2323-18, 12um mylar
• Near S2: 2623-26, 12um mylar
• Silicon pin diode: 0.9um mylar

The pin diode used in previous tests had something deposited (fingerprint?) on the crystal, so we replaced this with a new clean diode.

We mounted the detectors and foils inside the chamber, the target ladder was kept in its configuration with all blank frames (see eLog entry # 41). See attached picture 1 for the 12um mylar mounted in front of the far S2.

We mounted preamp I on the near position and preamp II on the far position, as will be used during the measurement.

We sealed the chamber to ensure it was light tight.

We applied pramp power, expected currents were drawn.

With no S2 bias we see high noise on the majority of the RAL amplifiers for both preamps I and II. We switched off the lab lighting and found the chamber was indeed light tight - there were no observable changes in noise.

We discovered CH2 of the Silena HV module does not supply bias.

We applied -10V bias to both S2's. The far S2 is biased using CH1 and the near S2 is biased using CH4 of the HV module. The leakage currents read: Far S2 = 0.35uA, Near S2 = 1.81uA.

With bias RAL X CH 0 baseline RMS noise ~ 55mV.

We biased the pin diode with its operating -70V using CH3 of the HV module, leak I = 0.01uA.

We decided to switch off all biases and prepare for tests under vacuum with an alpha source.

CH1 and 4 of the HV module were set to -130V ready for the S2's