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2017/10/09 (Monday)

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DCRC testing

0918 Power cycle DCRC3, now it's responsive to telnet again.
0944 Looking through ODB, notice that DCRC3 currently has QO threshold trigger enabled. How long has this been on? Looking at ODB files, it seems DCRC3 did have this charge threshold enabled for the tests Friday afternoon.
1030 Repeated some of those DCRC3 tests from Friday. It seems having the threshold trigger enabled may not have mattered. Either the threshold was set too high for triggers to happen or threshold triggering doesn't contribute to freezing.
1102 Also tried some test signal triggering. DCRC3 freezes with bad trace lengths (bold in the table below) for test signal triggers too. Furthermore, prepulse length seemed not to matter.
later Setting the phonon trace length to one of the “bad” values doesn't freeze it, nor does half of the “bad” value.
DCRC Triggering P Length P pre Q Length Q pre Lasts (min) Outcome
3 Rand 20Hz 8192 256 16384 512 >5 PASS
3 Rand 20Hz 8192 500 16384 500 >5 PASS
3 Rand 20Hz 8192 256 151384 512 <1 FAIL
3 Rand 20Hz 8192 500 151384 500 <1 FAIL
3 Rand 20Hz 8192 500 16888 500 >5 PASS
3 Rand 20Hz 8192 500 3928 500 <1 FAIL
3 TestSig 20Hz 8192 500 3928 500 <2 FAIL
3 TestSig 20Hz 8192 500 16384 500 >5 PASS
3 TestSig 20Hz 8192 500 151384 500 <1 FAIL
3 TestSig 20Hz 3928 500 16384 500 >3 PASS
3 TestSig 20Hz 1964 500 16384 500 >5 PASS
1700 Power down DCRC3. Plug DCRC4 into miniBOB and power on.
2035 After starting up, DCRC4 initially has 0x00,0x01=0000,0000 and 0x02=0x03=0x14=0000
2039 Disable DCRC3 and enable DCRC4 in ODB. Set DCRC4 as master. Turn off DCRC-based triggering, enable 20Hz randoms.
2043 After starting dcrc_driver, 0x00=updating and 0x02=0x03=0x14=0000
DCRC Triggering P Length P pre Q Length Q pre Lasts (min) Outcome
4 Rand 20Hz 8192 500 16384 500 >5 PASS
4 Rand 20Hz 8192 500 3928 500 <2 FAIL
4 Rand 20Hz 8192 500 151384 500 <2 FAIL
4 Rand 20Hz 8192 500 151384 0 <1 FAIL
2100 So it seems DCRCs 50, 55, and X (all C.1s) freeze up when run with these evil charge trace lengths.
2150 Confirm with pulse viewer that the frozen 0x00 corresponds to “stuck” output.
2236 After doing the most resent RESET, I've been unable to reconnect to the DCRC remotely. Maybe something funny is happening when I do this from home.

Changing 3He Pump Oil

1000 G2 (3He pump outlet) = 543.4 mbar. Pump is off, V9 is closed.
1000 Connect cryopump to vent at back of IGH. Open cryopump hose to G1, → 435 mbar. Pump this out with scroll pump.
1005 Check pressure in cryopump itself by opening black valve on cryopump. G1 does not increase. Must have held a good vacuum over several years since last used.
1030 Write up some procedures.
1055 stop pumping out cryopump.
1100 G2 = 540.2 mbar. Drifted a little since an hour ago
1105 Open V5 to open the 3He pump inlet to G1 and the cryopump. Was hoping that G1 would equalize with G2, that mixture would move backwards through pump and equalize on both sides. But this isn't happening. I wanted to cryopump mixture out of pump through the inlet side, but I guess this won't work.
1130 G2 has gone down slightly since opening to cryopump, 540.8→540.2 mbar. It's flat now. G1 also flat at 2.5 mbar.
1135 Turn on 3He pump to pump mixture back out of the cryopump
1145 Stop pumping out cryopump. Isolate cryopump, close V5, turn off 3He pump.
1145 We'll need to cryopump out the 3He pump outlet, not the inlet. So we'll need to go through a LN2 cold trap. Open Trap 2 to G1, → 6 mbar. Pump this out with scroll pump.
1200 Stop pumping out Trap 2.
1520 G2 (3He pump outlet) = 554.4 mbar. This has been falling slowly since turning off the pump at 11:45.
1520 Open V2, V7, Vent speedivalve, Cryopump black valve, to read cryopump on G1.
1520 Open V13b, which lets mixture from pump outlet into Trap 2. G2 falls 555→480 mbar, then continues to fall slowly
1525 Open V12b+speedivalve, which lets mixture from pump and Trap 2 into warm cryopump. G2 falls to 451 mbar, G1 rises to 506 mbar.
1530 Lower cryopump slowly into LHe Dewar. G1&G2 quickly fall below 100 mbar.
1540 G2 has fallen to 0 mbar. Apparently it is not sensitive below around 10 mbar. G1 = 8 mbar and falling.
1550 G1 = 3.8 mbar and falling.
1550 Turn on 3He pump to push more mixture out of pump. G1 rises a little, peaks at 5.0 mbar, then falls again.
1605 G1 = 3.0 mbar and pretty flat.
1605 Close V13b, isolating 3He pump. Then turn off 3He pump.
1610 Remove cryopump from LHe Dewar. While still pulling it out, noticed that G1 rose to 1 bar. Quickly opened V4 to release pressure to dump. G1 was overpressured for about 1 minute.
1615 G1 (cryopump+dump) = 883.8 mbar. Cryopump warming quickly, now cool to the touch and damp.
1620 G1 = 884.0 mbar, flat. Outside surface of cryopump = 20.7 C, c/w lab = 23.3 C.
1625 G1 = 884.0 mbar, cryopump surface = 23.0 C.
1630 Close V4, which isolates the dump.
will wait until tomorrow to continue. First thing will be to put cryopump back into Dewar.
Cryopump next to LHe Dewar. The Dewar is pushed as close to the IGH as we
could get it. The cryopump hose is draped over the 1K Pot pumping line.
When lifting it to lower into Dewar, have to avoid still pumping line. It
barely lifts high enough to insert into Dewar with a little strain.

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