ICEBERG and PD in ICEBERG: News and plans for run 2C and after - PDF document

ICEBERG and PD in ICEBERG: News and plans for run 2C and after Carlos Escobar 12/17/19 • Extensive work on cryogenics and electrical installation both CE and, to a lesser extent, PD. From Shekhar ’ s scheduling wiki: https://wiki.dunescience.org/wiki/Run_Plan_and_Project_Schedule

From the above current schedule we see that the PD must be inside the APA by 1/8/20 a Wednesday. What is being done with the PD? • The two Arapuca modules are out waiting for fixes on the electrical wiring and connections that will bring them in conformity with the DUNE grounding rules. Quoting from Terri Shaw ’ s messages to me (12/5): We will need to do some rework on both the Photon Detector panels so that we do not have floating wires on the inside. Each (cold) single ended signal travelling on a twisted pair must be connected to ground. So we will have a ground for Bias, +2.5V and - 2.5V. These three grounds should also be connected to the active ganging board – this is where we need to add a couple new wires. The splitter box will need to be modified so that it accepts a floating +2.5V with return, floating -2.5V with return and a floating bias with return from the new MPOD/ISEG modules we obtain. The “floating” reference will need to be grounded at the splitter box which MUST be close to the feedthrough and mounted on the top of the cryostat with a good connection to detector ground. All new warm cabling will need to be produced. Miguel is going to draw schematic for what we propose, starting with “cold” electronics. Once approved, we will need a space to do a small amount of soldering between the active ganging board and the pins plugging into the APA How are we doing with the above tasks? My answer: well behind the schedule. And, the above list does not say anything about the power supplies for the op-amp in the ganging circuit and for biasing the MPPCs (Wiener MPODs). On top of that we found that there are TPB flakes everywhere in ICEBERG (at the bottom, mostly) and stuck on the TPC (on the wires, and on the field cage). How do we know they are TPB flakes, not pTp or other stuff? Flashing UV light on them they luminesce with typical bluish hue (pictures taken by Flor)

Also, swabs were taken from the bottom of the cryostat, samples were taken by Ana to Brazil and were analyzed with a mass spectrometer and shown to be TPB. We need to open the standard Arapuca cells and examine the extent of TPB loss. I propose to do it today if there are no objections from the group.