2014/01/27
| 1450 | Fill LN2 cold trap full. |
|---|---|
| 1620 | Interrupt cryocleaning to commence pumping mixture to the dump. |
| 1725 | Initial throughput test gives throughput rate of roughly 7 mbar/min. This is much less than the expected rate of ~45 mbar/min. |
| 1805 | Throughput test Berkeley-style yields values listed in Tables 1 & 2. This is lower than that in test during a previous run (2013/10/26). |
| It is possible that poor throughput is due to higher mixing chamber temperature of 93-97 K during these tests. As we do not have any phonon channels on this crystal, it may be worth cooling down to liquid helium temperatures to determine what sort of base temperature we hit. |
| Table 1: Berkeley-Style Throughput Test 1 Results. | |||
|---|---|---|---|
| Time [s] | P1 [μbar] | G1 [± 1 mbar] | G2 [± 1 mbar] |
| 0 | 14 ± 0.5 | 677 | 609 |
| 20 | 15 ± 0.5 | 670 | 602 |
| 40 | 18 ± 0.5 | 671 | 602 |
| 60 | 38 ± 1 | 671 | 601 |
| 80 | 85 ± 2.5 | 671 | 601 |
| 100 | 160 ± 5 | 671 | 600 |
| 120 | 220 ± 5 | 671 | 600 |
| 140 | 300 ± 10 | 670 | 600 |
| 160 | 360 ± 10 | 670 | 599 |
| 180 | 400 ± 25 | 670 | 599 |
| 200 | 450 ± 25 | 670 | 599 |
| 220 | 550 ± 25 | 670 | 598 |
| 240 | 650 ± 25 | 670 | 598 |
| 260 | 750 ± 25 | 670 | 597 |
| 280 | 850 ± 25 | 670 | 597 |
| 300 | 950 ± 25 | 670 | 597 |
| Table 1: Berkeley-Style Throughput Test 2 Results. | |||
|---|---|---|---|
| Time [s] | P1 [μbar] | G1 [± 1 mbar] | G2 [± 1 mbar] |
| 0 | 17 ± 0.5 | 678 | 609 |
| 20 | 17 ± 0.5 | 671 | 602 |
| 40 | 20 ± 0.5 | 671 | 602 |
| 60 | 40 ± 1 | 671 | 601 |
| 80 | 90 ± 2.5 | 671 | 601 |
| 100 | 160 ± 5 | 671 | 600 |
| 120 | 220 ± 5 | 671 | 600 |
| 140 | 300 ± 10 | 671 | 599 |
| 160 | 360 ± 10 | 671 | 599 |
| 180 | 400 ± 25 | 671 | 598 |
| 200 | 450 ± 25 | 671 | 598 |
| 220 | 550 ± 25 | 671 | 598 |
| 240 | 650 ± 25 | 671 | 597 |
| 260 | 700 ± 25 | 671 | 597 |
| 280 | 850 ± 25 | 671 | 597 |
| 300 | 950 ± 25 | 671 | 597 |
| 1845 | Having recovered mixture (653 mbar - appears as though we lost some due to our leaky circulation pump last run), close gate valve and condenser line speedivalve to isolate fridge. Close all valves on IGH except V9. |
|---|---|
| Noticed that stopper had popped out from port into main bath at top of fridge. Port lies next to that used for transfer sticks. Probably popped out due to relatively high main bath pressure. Not sure when this occurred, and air may have leaked in. Evacuate main bath, and pressure drops below 0.5 mbar, indicating that there is probably no condensed water vapour inside main bath. Probably safe to commence transfer. Overpressurise main bath with He-4 gas. | |
| 1900 | Fill IVC with 0.046 mbar He-4 exchange gas. Commence helium transfer. |