2022/12/13 (Tuesday)
- Lab in-personnel: Matt
| Status | Run 76 ending |
|---|---|
| Setup | DCRC33(2)→HV control, NaI trigger signal → DCRCX(4) Lead/poly shield fully assembled. Boron-filled socks covering NaI detectors. PuBe removed from lab. |
| Warming up. Turbopumping cryostat vacuum jacket overnight. Mixture in dump. Mixture removed from LN2 Trap 1 but it still has contaminants. Some He exchange gas IVC. North and south lead removed from shield. NaI array powered down and vertical stack of NaI detectors (detectors 1-20) removed and put in cushioned boxes in LIGO lab. | |
| 1155 | Turbo on cryostat vacuum jacket (CVJ) = 140 nbar. With Turbo valved out for a minute CVJ = 4.0 ubar. That seems kind of high. Last time it got down to 0.74 ubar. |
| 1200 | MC(Cernox) = 277.2 K |
| MC hit 34 F = 274.26 K (approximately dew point) at 1:10 am this morning | |
| 1310 | Check contents of warm LN2 Trap 1: 155 mbar. Pump out with Scroll pump. |
| 1315 | Remove poly from North side of shield, store in storage closet |
| 1325 | Remove short boron socks from around bottom NaI detector layer. |
| 1330 | Remove PMT bases from ends of bottom layer NaI detectors 21, 22, 23 |
| Note: NaI Detector 21 is in West side and 23 on East side of thelab | |
| 1350 | Disconnect top bars from NaI rack that anchor it to the fridge stand. Then remove the NaI rack and put it in the LIGO lab. |
| 1355 | Remove lead sheets from floor of fridge shield, store in LIGO lab |
| 1410 | Remove E and W shield walls from lab, store them in storage closet |
| 1425 | Start pumping out IVC with Scroll pump. Planning to do the leak checks again, maybe we'll get a lower background at room temperature. Took 10 or 15 minutes to get below 0.1 mbar, then switched to Turbo pump. |
| 1545 | Leak detector on IVC = 927 pbarL/s. Squirt some helium at stripline elbow: signal increases to above 1000 pbarL/s. Repeat, signal peaks from 930 to 970 pbarL/s. |
| 1600 | Raise stripline elbow by wedging apart the two compression rings and shoving some washers between them. Connect leak checker to IVC again - background much higher, 3000 pbarL/s, but falling. |
| 1605 | LD on IVC relaxes to 800 pbarL/s. Squirt helium at stripline elbow, peaks to 850 pbarL/s. |
| 1610 | Try pushing vacuum grease into gap between compression rings and up using wood coffee stirrer. Try to work it all the way around, move the washers holding it up to one side to get that area too. |
| 1615 | LD on IVC = 745 pbarL/s. Squirt helium at stripline elbow, peaks to 785 pbarL/s. |
| 1620 | Remove washers and lower stripline elbow down as low as possible, so compression rings are touching. |
| 1620 | LD on IVC = 730 pbarL/s. Squirt helium at stripline elbow, peaks to 778 pbarL/s. No improvement. |
| 1625 | LD on IVC = 690 pbarL/s. Let mixture into fridge through V14, V3, V1, Still Gate valve, Condenser Speedivalve. No change in leak signal. |
| 1630 | Pump mixture back to dump. Open V6 to 13% at first, wait for fridge pressure to start to fall. Then open V6 to ~30%. |
| 1645 | Finish pumping mixture to dump. Close fridge valves and all IVC valves, turn off 3He pump. |