Drive folder with data files and some pictures:  https://drive.google.com/drive/folders/1Sr27kQTOO2kciBY7v-wYBP06tWLVEjiP

Lab notes @ CERN

11/10/2020

11:00 – First look at MB2.  Noticed on some of the PDMs that some of the tile PCB are more delaminated than others.  PDM 25 also had the FEB connectors more inserted than any other PDMs.  No other differences noticed.

11:30 – Connected SMU and switching matrix to MB2.  Power w/o steering module.  Checked that all channels match by running photo current tests with and w/o a flashlight on one corner.  Using the computer form Pisa with Labview scripts from Matteo.  Everything is ok.

12:00 – Replace plastic shields around Proto-0 for IV curve measurements in dark conditions.  PDM 1 breakdown is around 63V.  Looks ok.  PDM 2 is over 65V…. Seems high.

12:30 - PDM 6 People walking, disrupted the light conditions.  IV curve will be jagged.  Will go for lunch.  Closing door and turning off exterior lights.  Current will decrease

15:30 – IV curves look fine.  …/MB2_retriveval_CERN/data_files/iv_warm_1

16:00 – Took forward IV curves.  Saved as …/MB2_retriveval_CERN/data_files/forward_warm_1.  They look fine.  Checked old pictures of the lamination of the tile PCB and they have always varied in thickness, from before the LNGS LN test.

16:45 – Power FEBs on to look at noise spectra with 20V bias on the tiles.  

18:00 – PDM 2, 4, 6, and 25 have very odd power spectra.  George said they look like they’re not connected.

18:30 – Saving FFT to disk for analysis.  Saved as …/MB2_retriveval_CERN/data_files/noise_warm_1

19:00 – PDM 2,4,6 and 25 have one of the differential lines disconnected.  Using a light and looking at the differential outputs on the scope, this is obvious.  20V bias and FEBs powered at 5V.  Saved as …/MB2_retriveval_CERN/data_files/waveform_light_1

19:30 – Started another round of reverse IV curves in dark conditions.  Saved as …/MB2_retriveval_CERN/data_files/iv_warm_2

21:15 – IV still going.  EP will come back to shut off the LV supplies

12/12/2020

10:00 – Checking connectivity of all the differential lines.  One side of PDM 6 is not connected.  2, 4, and 25 are connected.  Doesn’t explain what we saw yesterday.  Channel 2 and 4 now are responding to light on both differential lines.  The only thing that has changed is unplugging the external signal cable and plugging it back in.  PDM 6 is the only one now not responding on both lines.

10:30 – Checking the power spectra.  PDM 4 and 6 are bad on both differential lines.  PDM 2 looks fine.  Seems to be non-repeatable.

11:00 – Disconnected the signal patch board from the finger strip.  Holding the patch and reconnecting the entire signal path and pinging now shows PDM 6 and 25 have one differential line disconnected.

11:30 – Checking the power spectra on every PDM channel directly from the fingerstrip with a flat cable.

12:30 – PDMs 2, 4, 6 power spectra from the fingerstrip look normal.  Both connections are there.  Light response is normal.  Channel 13, however, now has one differential line disconnected and the other looks abnormal.  Saving waveform data with 60Hz light on as waveform_light_2.

All of this is pointing to multiple connection issues…

15:00 – It looks like PDM 13 is disconnected from the fingerstrip, or at least it is pulled further away than the others.  This is likely also due to the removal of the patch.  PDM 2 also looks pulled a bit further.

15:30 – Unmounted MB2 and put on the stand to do an optical inspection.  The microscope didn’t allow a close enough look at the wirebonds to search for any broken ones.  A close look by eye didn’t reveal any obvious damage.

16:00 – Packed everything up.  MB2 needs a closer look, likely needs to be disassembled.