2025/06/30 (Monday)

Status	Run 83 ended. Himangshu back from leave. Evaluating Status for 1K pot test
1000	Turbo pump is turned off, switch is off. Valve on top of pump closed so IVC is still in vacuum. Switch on Turbo pump
1030	Remember that gauge reading is on top of pump Tee now, not underneath the Tee. So connecting scroll to Tee and pump the volume out to get to vacuum
1040	Gauge reading : 1.2e-4 mbar and going down. Turbo pump is working fine .
	Lead sheets need to be removed or wrapped with plastic in Room 53. Mike said he can help if not on Tue or Thusrday

1048	The Tee leak is quite more than earlier seen. Pressure gauge reading jumped from 4.6e-4 to 8.6e-3 in about a minute. That's more than the about the time needed to add He during exchange gas step. We might be adding more air than expected through this leak, which might be a cause of frequent clogs in the later cooldown steps
1055	Turning off Turbo and undo the whole Tee structure to apply vacuum grease to all four o-rings
1151	Cleaner all 4 o-rings with ISO and then applied vacuum grease. Rechecked with turbo, leak is still quite high (e-4 to e-2 in 16 seconds) . Attaching Leak detector to point out which o-ring is leaky
1335	Leak checking Tee: Initial Gauge Pressure: 1.9e-4 mbar, At 1 min 50 sec, Pressure: 1e-3 mbar, At 3 min 17 sec, 1.9e-3 mbar, At 4 min 52 sec, Pressure: 3.0e-3 mbar. The only change is the connection to the leak detector line(replaced blank with leak detector bellow).

minutes	mbar (P2)
1409	Pump out 1K pot with scroll pump. With needle valve completely closed, close off pump and see how fast pressure rises:
0	8e-2
0.5	2e-1
0.75	3e-1
1.0	3.8e-1
1.25	4e-1
1.5	4.5e-1
1.75	5.2e-1
2.0	6e-1
2.5	6.7e-1
3.0	8e-1
1439	Try another test to see how fast the 1K Pot pressure rises when the pump is closed off, but this time with needle valve open 5 full rotations:
1500	Steps: Keep Main bath valve closed, MB at atm pressure. Open 1K speedivalve to pump out. Open needle valve 5 full rotations. Close scroll pump valve. Within <30 seconds, P2 went off-scale, G3 is at 300 mbar
	With the scroll pump valve open, we start the needle valve 0.25 turns at a time
turns	mbar (P2)
0	0.1
0.25	0.6
0.5	1.7
0.75	3.0
1.0	3.5
1.5	5
2.0	5
3.0	5.5
4.0	5.5
5.0	5.5
1506	This tells us that there is no blockage on the connection through the needle valve at room temperature. I recall that doing the similar test during cooldown, I was trying to pump on the 1K with needle valve open wide and I donot see any change in pressure on P2, which indicates that there was a blockage at He4 temperatures.