2016/09/16 (Friday)
| Status: LHe in bath, turbopumping IVC overnight. Mixture in fridge overnight. | |
| 0835 | MC(Cernox)/Sorb/1K Pot = 20.4/8.3/6.3 K, Turbo/IVC = 1.2/5.4 nbar, G1/G2 = 575/530 mbar, MB = 70.2% |
| Temperatures rose and peaked somewhere around midnight, then began falling | |
| 0845 | Tower/MC(H35)/Coldplate/Still = 20.7/17.2/offscale/11.6 K |
| 0850 | Fill LN2 cold trap bath |
| 0855 | Turn on 4He pump, open pump valve. Open the two valves to connect pump exhaust to recovery. Open V4a to pump out the G3 volume. |
| 0905 | Open 1K Pot needle valve to almost 180 degrees then close again. Pot temperature doesn't really change, odd Close 4He pump valve then open 1K Pot speedivalve. 1K Pot pressure around 0.7 bar, I guess it's full of helium… |
| 0910 | Open 4He pump valve a little to start pumping on 1K Pot. 1K Pot falls quickly to 3.6 K. Sorb also falls to 4.6 K. |
| 0915 | 1K Pot has risen to 5.4 K. Open 4He pump valve all the way. 1K Pot pressure falls to 0.3 mbar. |
| 0920 | Open 1K Pot needle valve about 50 degrees. 1K Pot → 2.5 K / 20 mbar. G1/G2 falling at about 20 mbar/minute. Sorb bottoms out at 4K minimum. Still falls to 3.2 K, Coldplate falls into readable range = 30 K |
| 0925 | 1K Pot = 2.0 K / 19 mbar, G1 (fridge) = 510 mbar and flat, kind of high. Try opening needle valve additional 10 degrees: 1K Pot → 1.8 K / 40 mbar, G1/G2 falling again. |
| 0935 | G1 (fridge) = 450 mbar and falling steadily at 7 mbar/min. 1K Pot steady at 1.75 K / 40 mbar. |
| 0955 | G1 (fridge) = 360 mbar and falling more slowly. 1K Pot = 1.67 K / 20 mbar. Open needle valve additional 5 or 10 degrees. 1K Pot → 1.7 K / 50 mbar, G1 falls more quickly |
| pause for meeting… | |
| 1015 | during meeting looks like 1K pot emptied, pressure fell below 10 mbar and temperature rose. Fridge pressure also began to rise. G1 fell to minimum of 270 mbar |
| 1115 | G1 (fridge) = 500 mbar and flat. 1K Pot = 3.3 K / 2.2 mbar. Open needle valve 10 more degrees. 1K Pot → 2.3 K / 30 mbar, G1 falling again. Open needle valve a few more times to get temperature below 2K |
| 1120 | MC(Cernox) has been falling Tower/MC(Cernox)/MC(H35)/Coldplate/Still = 11.3/11.1/10.3/4.4/3.1 K |
| 1125 | G1 (fridge) = 385 mbar and falling at 14 mbar/min, 1K Pot = 1.8 K / 45 mbar |
| 1140 | G1 (fridge) = 230 mbar and falling at 13 mbar/min, 1K Pot = 1.7 K / 20 mbar. Tweak open the needle valve further to get pressure back to about 40 mbar. |
| 1145 | Tower/MC(Cernox)/MC(H35)/Coldplate/Still = 3.2/2.7/2.5/3.2/2.2 K |
| 1155 | G1 (fridge) = 95 mbar, 1K Pot = 1.6 K / 15 mbar. Tweak open the needle valve further. |
| 1205 | G1 (fridge) = 65 mbar and flattening, 1K Pot = 1.7 K / 80 mbar (after a tweak). MC(H35) = 2.2 K |
| 1215 | Close V9, leaving 65 mbar in the dump. Turn on the 3He pump, pushing more mixture into the fridge. Also close V3 (a little late) so we are only pushing mixture into the condenser side. Small increase in G1, then it falls again, no other changes. |
| 1220 | Tower/MC(H35)/Coldplate/Still = 2.2/2.2/2.6/1.8 K. 1K Pot = 1.65 K / 22 mbar, tweak open needle valve more, → 1.7 K / 60 mbar. |
| 1225 | Start circulation. At V6 = 12.8% see response, G1/G2 were both 65 mbar, → 70/80 mbar. G2 higher - impedance in LN2 trap? |
| 1235 | at V6 = 13.2%, strong drop in Still temperature and increase in G2, small spike in 1K Pot |
| 1240 | V6 = 13.2%, Still = 1.63 K / 1000 mbar, G1/G2 = 90/120 mbar, Coldplate/MC(H35)/Tower = 2.03/1.68/1.74 K, 1K Pot = 1.64 K / 19.0 mbar tweak 1K Pot needle valve again |
| 1250 | V6 = 13.4%, Still = 1.47 K / 1000 mbar, G1/G2 = 105/140 mbar, Coldplate/MC(H35)/Tower = 1.83/1.54/1.59 K, 1K Pot = 1.68 K / 32.0 mbar |
| 1255 | V6 = 13.6%, Still = 1.33 K / 75 mbar, G1/G2 = 110/150 mbar, Coldplate/MC(H35)/Tower = 1.65/1.43/1.53 K, 1K Pot = 1.64 K / 19.0 mbar (tweak again) |
| 1300 | Apply power to the two DCRCs. |
| 1310 | V6 = 14.0%, Still = 1.08 K / 5.0 mbar, G1/G2 = 110/130 mbar, Coldplate/MC(H35)/Tower = 1.15/1.12/1.16 K, 1K Pot = 1.70 K / 40.0 mbar |
| 1315 | Initial look at pulses. Setup: EBoxDIB 2/3 → 3.2 MHz filters → Cables → remapping board I/remapping board II → HVside2board “DIB1”/“DIB2” → DCRC55(1)/50(3). Remapping boards have necessary(but not all possible) lines switched off. |
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| The readout channel is DCRC1qO. Some sinusoidal noise, no pulses seen. Applied 5 and 10 V to readout side using DCRC. Grounded the HV input to the board to ground the HV side. Set QET and SQUID biases to zero. (Some QET lines are attached to LEDs so want the biases to be zero.) No pulses seen so far. | |
| Set DCRC bias to 0. Applied voltage with HV board. |
| HV (V) | leakage (mV) | V_crystal (V) |
|---|---|---|
| 5 | 10.7 | 0.3 |
| 10 | 22.9 | -0.08 (consistent with 0) |
| 1320 | At HV=10V, sinusoidal noise (~0.07Vpp, ~160Hz) returns. Turn off HV, sinusoidal noise goes away. |
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| 1325 | V6 = 14.6%, Still = 1.00 K / 2.2 mbar, G1/G2 = 110/125 mbar, Coldplate/MC(H35)/Tower = 0.74/0.50/0.72 K, 1K Pot = 1.64 K / 18.0 mbar (tweak again) |
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| 1335 | V6 = 15.0%, Still = 1.02 K / 1.4 mbar, G1/G2 = 100/115 mbar, Coldplate/MC(H35)/Tower = 0.95/0.36/0.54 K, 1K Pot = 1.64 K / 18.0 mbar (tweak again) |
| 1345 | Open V6 100% |
| 1335 | V6 = 100%, Still = 0.97 K / 0.22 mbar, G1/G2 = 110/125 mbar, Coldplate/MC(H35)/Tower = 0.37/0.20/0.42 K, 1K Pot = 1.65 K / 22.0 mbar (tweak again) |
| 1400 | V6 = 100%, Still = 0.95 K / 0.14 mbar, G1/G2 = 90/100 mbar, Coldplate/MC(H35)/Tower = 0.29/0.086/0.36 K, 1K Pot = 1.65 K / 20.0 mbar (tweak again) |
| 1410 | Open V14 to let remaining mixture from dump into circulation. G1/G2 increase to 130/155 mbar then fall again. P1 maxes out but then drops quickly below 40 mbar. 1K Pot remains stable. MC rises from 80 to 140 mK. |
| 1420 | V14 open, Still = 0.93 K / 2.4 mbar, G1/G2 = 85/90 mbar, Coldplate/MC(H35)/Tower = 0.30/0.087/0.33 K, 1K Pot = 1.58 K / 8.5 mbar (tweak again) |
| 1435 | V14 open, Still = 0.97 K / 0.70 mbar, G1/G2 = 100/105 mbar, Coldplate/MC(H35)/Tower = 0.30/0.077/0.31 K, 1K Pot = 1.66 K / 24.0 mbar |
| 1440 | Close V14 |
| 1500 | V14 closed, Still = 0.89 K / 0.09 mbar, G1/G2 = 75/85 mbar, Coldplate/MC(H35)/Tower = 0.33/0.082/0.29 K, 1K Pot = 1.48 K / 4.0 mbar (tweak again!) |
| 1510 | MB = 56.1%. Fridge seems to be boiling in fast mode (or worse). At 9am tomorrow morning it will be down to 20%… |
| 1555 | V14 closed, Still = 0.98 K / 0.13 mbar, G1/G2 = 125/125 mbar, Coldplate/MC(H35)/Tower = 0.30/0.069/0.24 K, 1K Pot = 1.66 K / 26.0 mbar (tweak again) |
| 1635 | V14 closed, Still = 1.01 K / 0.15 mbar, G1/G2 = 135/135 mbar, Coldplate/MC(H35)/Tower = 0.30/0.065/0.21 K, 1K Pot = 1.74 K / 80.0 mbar (after a tweak) |
| 1740 | Conduct a series of small tests to determine 1) Whether the LEDs turn on and 2) What parameters should be used with both types of LEDs. Begin with IR LEDs and standard LED flashing parameters (LED pulse width = 100, Rep Rate= 5000, Current = -0.6) but change the Flash ON time to 0.5 s and the OFF time to 0.45 s, with a duration of 10 seconds. Take data while flashing just with DCRC1 with this setup and ConnectLEDVoltagesToPhononADCs enabled (Data 07160916_1659). Also we can see a pulse indicating the LED is active, it does not have the typical shape of the LED pulse. Take data again after reversing current to +0.6 (we had expected this LED to need positive current), but keep all other parameters the same (Data 07160916_1711). Pulses look more typical of LED pulse. Also notice that tower temperature increases from 175 mK to 228 mK during this flash. |
| 1742 | Switch from IR LEDs on DCRC1 to UV LEDs (using switch boards). While watching pulses in GUI, flash for 10 seconds using standard parameters and a current of +0.6. Peaky looking pulses are seen, but they do not have the shape of LED pulses (see Run 60 summary page for example). No significant change in temperature was seen. Switch current to -0.6 and flash for another 10 seconds while watching pulses. LED pulses looked more typical, with slanted downward edge before falling tail. During this flash the fridge temperature rose from 174 mK to 180 mK, significantly less than the IR temperature rise, but perhaps this is OK. Try one more DCRC1 UV flash with current at -0.8, seeing good LED peaks again and a temperature rise from 173 mK to 182 mK. It seems that at least one of the UV LED works, but more studies will have to wait till tomorrow. |
| 1743 | Now lets look at DCRC3 IR LEDs. Using the same settings, flash for 10 seconds on DCRC3 IR LEDs while watching pulses in GUI. As before, pulses appear standard. Flash for 10 seconds using both DCRC's, and see temperature increase from 159 mK to 257 mK. |
| 1745 | Commence 12 hour bake with IR LEDs on both DCRC's (currently connected through HV board). During bake tower temperature rises to 540 mK and seems stable. |
| 1758 | Notice that 1K Pot is at 1.45 K / 1.7 mbar. Open 1K Pot about 15 more degrees. Give time to settle. |
| 1803 | After 5 minutes the 1K Pot is at 1.93 K / 1 bar (off charts). Keep an eye on it. |
| 1818 | Fill LN2 cold trap full. |
| 1820 | 1K Pot at 1.7 K / 65 mbar. Tweak another 15 degrees. |
| 1826 | Calling it for the night. The bake seems fine, 1K Pot at 1.94 K / 1 bar (off charts) but the temperature isn't changing crazily or anything. G1 / G2 = 234 mbar / 230 mbar, and P1 = 0.24 mbar. He level at 49.7%. Leaving boards powered on overnight, with HV off of course. |