2022/07/28 (Thursday)
- Lab in-personnel: Matt, Giulia
| Status | Run 76 in progress |
|---|---|
| Setup | Cables 2/3/1 → diverter/nothing/nothing → Side2-readout HV CONN 1/3/2 → HV 1(L)/2(R) → DCRC50(3)/DCRC55(1), DCRC33(2)→HV control, NaI trigger signal → DCRCX(4) Lead/poly shield fully assembled. Boron-filled socks covering NaI detectors. PuBe behind lead wall on West side of lead/poly shield. |
| Fridge failure three days ago, looks like an impedance blockage. Warming up. Helium in cryostat vacuum jacket and IVC. All mixture in dump. Still and MC heaters on. Both LN2 traps warm, need contaminants pumped out. | |
| 0930 | MC/Sorb = 100/201 K |
| 0930 | Recovery = 6213?? cuft |
| 0940 | Check contents of warm LN2 Trap 1: 165 mbar (very high). Pump out with Scroll pump |
| 0950 | Check contents of warm LN2 Trap 2: 7.2 mbar. Kinda high considering how short a time it was used. Pump out with Scroll pump |
| 1205 | Check fridge pressures: LHe trap first, by opening V1: 378 mbar, very high. Pump out with scroll pump. |
| 1205 | Condenser/Still = 1.0/0.82 mbar; pump out with Scroll pump. |
| Throughput test procedure, Cold Trap 2: |
- All mixture in dump, LN2 trap 2 cold, condenser & still valves open (3He pump on - optional)
- Open V9, V13b, V12b+speedivalve, V3. Wait for G1 to be close to G2.
- Close V12b+speedivalve and V3, open V1
- monitor G1
| 1215 | Perform mixture throughput test at MC = 117 K using above procedure with 3He pump off. Let G1 rise to 520 mbar before Step 3, then it falls to 44 mbar and starts to rise. Throughput = 19.3 mbar/min. |
|---|---|
| Huh, this is not bad. Is the blockage already gone? Should repeat with pump on… | |
| 1235 | Perform mixture throughput test at MC = 119 K using above procedure with 3He pump on. Let G1 rise to 532 mbar before Step 3, then it falls to 47 mbar and starts to rise. Throughput = 19.8 mbar/min. |
| 1330 | Pump mixture from fridge to dump |
| 1335 | Start cryocleaning mixture through LN2 Cold Trap 2, V6 = 12.8% |
| 1335 | Check cryostat vacuum jacket: 0.1 mbar. Start pumping out with Turbo pump. |
| 1350 | Increase V6 → 12.9% to restart flow |
| 1350 | Increase V6 → 13.0% to speed up flow |
| 1405 | Stop cleaning through Trap 2 after 30 min. G2 flow pressure was 575-650 mbar. Pump mixture to dump. Removed 8.2(6.7) mbar. |
| 1425 | Turbo on Cryostat Vacuum Jacket = 140 nbar |
| 1425 | Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.9% |
| 1435 | Increase V6 → 13.0% to restart flow |
| 1455 | Stop cleaning through Trap 1 after 30 min. G2 flow pressure was 580-620 mbar. Pump mixture to dump. Removed 8.8(8.1) mbar. |
| 1500 | Remove PuBe source can from its paraffin drum, disconnect it from the plexiglass rod, and put it in plastic cup and lower it on string into lead/poly shield on NW corner. This is the same configuration as for the strong Ge activation - source should be at about SiHV detector level. We're going to take overnight NaI scan data. |
| 1505 | Turbo on Cryostat Vacuum Jacket = 76 nbar. With Turbo valved out for 1 minute CVJ = 1 ubar. |
| 1515 | Check contents of warm LN2 Trap 2: base pressure 1.7 mbar, trap pressure 9.9 mbar. Pump out with Scroll pump. Final pressure 3.2 mbar. |
| 1520 | MC/Sorb = 133/>250 K |
| 1540 | LHe Recovery = 6213?? cuft. Rate essentially 0. |
| 1545 | Close MB recovery valve |
| 1545 | Turn off MC and Still heaters |
| 1610 | Check contents of warm LN2 Trap 1: base pressure 1.8 mbar, trap pressure 10.6 mbar. Pump out with Scroll pump. Final pressure 2.5 mbar. |
| 1655 | Turbo on Cryostat Vacuum Jacket = 76 nbar. With Turbo valved out for 1 minute CVJ = 0.86 ubar. |