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2017/10/13 (Friday)

Previous Day

DCRC testing

1600 Test DCRC52(6) from Berkeley some more. So far we haven't been able to make it freeze with any of the “bad” charge trace lengths that affect DCRC1/3/4. We'll test values shown to be bad on DCRC4.
DCRC Triggering P Length P pre Q Length (dec) Q Length (bin) Q pre Lasts (min) Outcome
6 Rand 20Hz 8192 0 24 11000 0 >5 pass
6 Rand 20Hz 8192 0 56 111000 0 >5 pass
6 Rand 20Hz 8192 0 88 1011000 0 >5 pass
6 Rand 20Hz 8192 0 344 101011000 0 >5 pass
6 Rand 20Hz 8192 0 856 1101011000 0 >5 pass
6 Rand 20Hz 8192 0 1880 11101011000 0 >5 pass
6 Rand 20Hz 8192 0 3928 111101011000 0 >5 pass
6 Rand 20Hz 8192 0 20312 100111101011000 0 >5 pass
6 Rand 20Hz 8192 0 151384 100100111101011000 0 >5 pass

Tower Disassembly/Reassembly

Status: shorts between pA, pB, pE have been fixed by bending wirebonds. Knocked the detector around a bit to convince ourselves the fixes would hold. Tower is reassembled. Electrical checkout done except for LEDs on DIBs.
1520 Perform tower electrical check for DIB LEDs:
Tower Level Checkout
Detector S1502 Date 2017-09-13 Who MF
DIB 1 Face 5 Side Coax ZB1-1-9
+lead - lead signal typical prev. measured
9 chassis LED1 Rforward 8 to 9 MΩ < 0.1 nS < 0.1 nS
9 chassis LED1 Vforward 1.0 to 1.1 V OL OL
chassis 9 LED1 Rreverse <1 nS < 0.1 nS < 0.1 nS
10 chassis LED2 Rforward 8 to 9 MΩ < 0.1 nS <0.1 nS
10 chassis LED2 Vforward 1.0 to 1.1 V OL OL
chassis 10 LED2 Rreverse <1 nS 0.1 nS <0.1 nS
DIB 3 Face 3 Side Coax ZB1-1-11
+lead - lead signal typical prev. measured
9 chassis LED1 Rforward 8 to 9 MΩ 0.77 MΩ <0.1 nS
9 chassis LED1 Vforward 1.0 to 1.1 V 1.103 V 1.096 V
chassis 9 LED1 Rreverse <1 nS 0.3 nS 769 kΩ
10 chassis LED2 Rforward 8 to 9 MΩ 0.715 MΩ 0.685 MΩ
10 chassis LED2 Vforward 1.0 to 1.1 V 1.072 V 1.067 V
chassis 10 LED2 Rreverse <1 nS 22 MΩ 16 MΩ
DIB 4 Face 2 Side Coax ZB1-6
+lead - lead signal typical prev. measured
9 chassis LED1 Rforward 8 to 9 MΩ 0.79 MΩ 0.775 MΩ
9 chassis LED1 Vforward 1.0 to 1.1 V 1.106 V 1.102 V
chassis 9 LED1 Rreverse <1 nS < 0.1 nS < 0.1 nS
10 chassis LED2 Rforward 8 to 9 MΩ 0.763 MΩ 0.754 MΩ
10 chassis LED2 Vforward 1.0 to 1.1 V 1.105 V 1.101 V
chassis 10 LED2 Rreverse <1 nS 0.2 nS 0.1 nS
1550 Begin installing tower.
1630 Installing 100mK shields
1710 Installed 100mK shield and heatsinks.

Putting 3He Pump Back in Service

Status: New oil in 3He pump. Pumped mixture out of cryopump and into dump overnight. Still a little mixture in Trap 2.
1725 P1 (cryopump) = 0.180 mbar and falling. G2 (dump) = 738.5 mbar and rising.
0850 P1 (cryopump) = 0.034 mbar. Steady fall overnight, pretty flat now. G2 (dump) = 732.0 mbar. This has decreased overnight, possibly just due to change in atmospheric pressure. It's lower than the ~780 mbar level we had before the oil change it seems. Did we lose a little mixture? Should do a careful comparison.
0850 3He Pump oil level = 40%. Bouncy meniscus, some bubbles.
0855 Close black valve on cryopump. P1 falls a little, to 0.020 mbar.
0900 Close Vent speedivalve. P1 falls slightly, to 0.018 mbar. We have now pumped out the cryopump.
0900 Open V12b+speedivalve to view Trap 2 pressure on G1. G1 actually falls from 5 to 2 mbar. (More air had leaked into IGH than there was mix still in the trap.)
0905 Close V7, open V2. Now pumping out Trap 2 to dump through V12b+speedi, V2, V8, V6, V9.
0905 G1/P1 (Trap 2) → 1.8/0.300 mbar. G2 (dump) increases, 732→735 mbar.
0940 G1/P1 (Trap 2) = 1.9/0.260 mbar. Pretty flat. G2 (dump) = 734.3 mbar. (G2 falling at same rate as before, possibly due to the weather.)
1050 G1/P1 (Trap 2) = 1.8/0.200 mbar. Pretty flat. G2 (dump) = 733.3 mbar. This is certainly long enough. Stop pumping out Trap 2.
1100 Prepare to cryoclean mixture. Put Cold Trap 2 in bath and fill bath with LN2.
1110 Begin cryocleaning mixture through Trap 2. V6 open to 12.8%.
1115 Flow stopped, increase V6 to 13.1% to re-establish flow.
1125 Flow stopped, increase V6 to 13.4% to re-establish flow. This was too much - close V6, then restart. Open V6 to 13.1% to establish flow.
1135 Flow stopped, increase V6 to 13.3% to re-establish flow.
1155 Stop cryocleaning after 45 minutes.
1225 Trap 2 is pumped out. G2(dump) = 734.0 mbar, pretty flat. Remove Trap 2 from bath to let warm up. Put Trap 1 into bath for a second cleaning.
1230 Begin cryocleaning mixture through Trap 1. V6 open to 13.3%.
1235 Flow stopped (or very slow), increase V6 to 13.4% to re-establish flow.
1315 Oops - looks like I had V9 open during the cleaning. So wasn't really flowing through the trap.
1320 Begin cryocleaning mixture through Trap 1. V6 open to 13.1%. This time V9 is closed as it should be.
1330 Flow stopped, increase V6 to 13.2% to re-establish flow.
1400 Flow stopped, increase V6 to 13.3% to re-establish flow.
1410 Stop cryocleaning after 50 minutes.
1440 Trap 1 is pumped out. G2(dump) = 730.0 mbar, rising slowly. Remove Trap 1 from bath to let warm up.
1440 Open (warm) Trap 2 to G1. G1 = 331 mbar. That's a lot of contamination! Pump out with scroll pump.
1455 Replace Trap 2 in LN2 bath.
1500 Begin cryocleaning mixture through Trap 2. V6 open to 13.0%.
1500 Flow stopped, increase V6 to 13.1% to re-establish flow.
1505 Flow stopped, increase V6 to 13.2% to re-establish flow.
1530 Flow stopped, increase V6 to 13.3% to re-establish flow.
1550 Stop cryocleaning after 50 minutes.
1615 Trap 2 is pumped out. G2(dump) = 733.7 mbar, rising slowly. Remove Trap 2 from bath to let warm up.
1620 Open (warm) Trap 1 to G1. G1 = 5.0 mbar. That's a lot less than last time. Pump out with scroll pump.
1640 Put Trap 1 back in LN2 bath.
1705 G2 (dump, with 3He pumping for a while, V6 closed) = 734.5 mbar. Close V9 and turn off pump.
1620 Trap 2 is nearly room temperature and open to G1. G1 = 5.2 mbar. Pump out with scroll pump.
Cryocleaning log
date duration (minutes) contaminants removed (mbar)
Oct 13 45 331
Oct 13 50 5.0
Oct 13 50 5.2
This already looks good, compare last run. Although it does look like we did shorter cleanings today than last couple runs.
1720 Pumped out Trap 2 but may not be complete, still a little cool. Should pump it out again later.
Mixture amounts
Date/time G1 [mbar] Barometric [inHg] Dump, corrected [mbar] notes
2017-Oct-02 13:05 780.6 29.90 779.9 before oil change
2017-Oct-12 17:25 738.5 29.92 738.5 after oil change
2017-Oct-13 08:50 732.0 30.13 739.1
2017-Oct-13 17:05 734.5 30.12 741.3
looks like we dropped from 780 to 740 mbar of mixture after the oil change.

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