2018/02/26 (Monday)
More on the bad channel from Run 58, q3/DIB1qI:
Trying to go through the symptoms, notes are not entirely clear. But apparently the Qbias-QETreturn measurement (in this case “QET return” is the connection to detector “ground” electrode on opposite side from the readout electrodes) showed too-high resistance at 96 K. And pulses were small. This may not have been a problem at the detector but rather maybe the connection to the bias resistor - either a break at the side coax or a break in the stripline. The resistance seen may have been through a short, and there may have been no connection at all.
In Run 58, DIB1 was connected to Side Coax ZB1-1-11 and SQUET ZC-39 and I think Stripline 19. We may want to avoid these.
In Run 63 we ran the iZIP pathfinder and used Side Coaxes ST-3-3, ST-3-9, ST-3-10. Probably we can re-use two of these.
Recently we've used non-modified SQUETs ZC-13, ZC-26, ZC-37. We can use two of these.
so we can avoid re-using any of the possibly bad hardware.
| 1255 | Begin disassembling Run 66 tower |
|---|---|
| 1305 | Removed adapter ring |
| 1320 | Side coaxes removed. The extenders were left on the tower, need to desolder the LED wires. |
| 1330 | Detector USD1 electrical checkout: |
| USD1 pinout map | ||||
|---|---|---|---|---|
| DIB1qO | DIB1qI | DIB2qO | DIB2qI | DIB1pin7 |
| q1 | q3 | q2 | q4 | g |
| Charge channels are numbered outer-to-inner | ||||
| A “1” is scratched onto housing above DIB1 (a little hard to see) | ||||
| DIB1 is the DIB nearest to the housing serial number | ||||
USD1 electrical checkout, cross-channel resistances:
| q1 | q2 | q3 | q4 | g | chassis | |
|---|---|---|---|---|---|---|
| q1 | - | 21.7 (21.5) | 35.1 (36.5) | 49.8 (49.8) | 15.1 (14.8) | open |
| q2 | - | - | 31.9 (33.9) | 39.0 (39.1) | 11.3 (11.2) | open |
| q3 | - | - | - | 59.1 (60.5) | 26.5 (27.0) | open |
| q4 | - | - | - | - | 39.0 (34.8) | open |
| g | - | - | - | - | - | open |
| resistances between four charge channels and ground connection on opposite side |
||||||
| (parantheses) indicate previous measurements from 2016 May 25 | ||||||
| All 4 LEDs show similar measurements to 2016 May 25 | ||||||
| 1340 | Tower disassembly continued: removed source/LED holder, along with the two side coax extenders with LED wires still soldered to them. |
|---|---|
| 1345 | Remove G101c from tower and return it to purge. |
| 1350 | Remove the soldered wires from the side coax extenders. |
| 1355 | The source holder plate that was used in the last run seems to be the correct one for this run - it has places to mount 2 large and 2 small sources. (The other one we used for the SiHV run has 3 large source mounts and 1 small one). So, we are removing the external LED chips from this plate since we don't need them for this run. Also remove tower thermometer for now. |
| 1710 | Mount 4 Am sources onto source plate designed for the 4-Q 100mm mask. I used the bare source in the center with the larger 18mm collimator. For the outermost source it was necessary to use the offset collimator with the small pin to lock it into the correct orientation. |