BHR Upgrade Phase I - Vent of Fall 2021

1. Venting process

Mon Oct 18th, 2021

• Checked the main volume is isolated.
• TP1 and TP2 were made isolated from other volumes. Stopped TP1. Closed V4 to isolate TP1 from TP2.
• TP3 was made isolated. TP3 was stopped.
• We wanted to vent annuli, but it was not allowed as VA6 was open. We closed VA6 and vented the annuli with VAVEE.
• We wanted to vent the volume between VA6, V5, VM3, V7 together with TP1. So V7 was opened. This did not change the TP1 pressure (P2 = 1.7mmTorr) .
• We wanted to connect the TP1 volume with the main volume. But this was not allowed as TP1 was not rotating. We will vent TP1 through TP2 once the vent of the main volume is done.
• Started venting the main volume@Oct 18, 2021 9:45AM PDT
• We started from 10mTorr/min, and increased the vent speed to 200mTorr/min, 700mTorr/min, and now it is 1Torr/min @ 20Torr
• 280Torr @11:50AM
• 1atm @~2PM

We wanted to vent TP1. We rerun the TP2 and tried to slowly introduce the air via TP2. But the interlock prevents the action.

1.1. Elog posts

• 40m/16410: Vent Started/Completed

2. Part I: Optics removal on westside of BS Table

• We removed the following optics from the BSC table and stored them in X-end flowbench with fan on. See attachment 1 and 2.
  1. IPPOS SM2
  2. GRX SM2
  3. PRM OL1
  4. PRMOL4
  5. IPPOS SM3
  6. IPANG SM1
  7. PRM OL2
  8. Unidentified optic inbetween IPPOS45P and IPPOS SM3
  9. Beam block behing PR3
  10. Beam block behind GR PBS
  11. GR PBS
  12. GRPERI1L (Periscope)
  13. PRMOL3
  14. IPPOS45P
  15. Cylindrical counterweight on North-west end of table.
  16. Cheap rectangular mirror on South west end of table (probably used for some camera, but not in use anymore)
  17. IPANGSM2
• We also changed the direction of clamp of MMT1 to move it away from the center of the able (where PRM will be placed)
• We screwed in the earthquake stops on PRM and BS from front face and top.
• We unscrewed the cable post for BS and PRM oplevs and loved it in between SR3 and BS and screwed it lightly.
• We moved the PRM, turned it anti-clockwise 90 degrees and brought it in between TT2 and BS. Now there is a clear line of sight between TT2 and PR2 on ITMY table.

• We opened the laser head shutter.
• we scanned around the PMC resonance and locked it. We then opened the PSL shutter, touched the MC1, MC2 and MC3 alignment (mostly yaw) and managed to lock the IMC.
• The transmission peaked at ~ 1070 counts (typical is 14000 counts, so at 10% of PSL power we would expect a peak transmission of 1400 counts, so there might still be some room for improvement).
• The lock was engaged at ~ 16:53, we'll see for how long it lasts.

2.1. Elog posts

• 40m/16425: Removed optics from BSC

• 40m/16429: Locked PMC and IMC

3. Part II: Relocation of TT2 and MMT1/2 alignment to TT2

4. Part III: PRC Folding mirror placement

1. 40m/16432: Removal of PR2 mirror

2. Placing a fixed mirror on a new PR2 location.

3. Replacing PR3 with SOS with new optic (E1800089).

4. Aligning TT2, PR2 and PR3 to get beam to BS center.
5. Set up 2-3 irises.
6. Put in PR2 in SOS.
7. Align the beams back to the irises.

5. Part IV: SR3 replacement

1. Clear East side of BS table. Following optics need to be removed:
   • OM4-PJ
   • GRX_SM1
   • OM3
   • BSOL1

6. Part V: SRM Oplev setup

7. Part VI: POY Path setup

8. Part VII: LO Path up to LO2 setup

9. Part VIII: AS Path setup

• Clear the ITMY table. Following optics need to be removed:
  • POYM1
  • ITMY OL1
  • ITMY OL2
  • ..

10. Part IX: BHDBS Path setup

• Setting up LO3, LO4, BHDBS

11. Part X: POP Path setup

12. Part XI: POX Path setup

13. Part XII: AS RFPD Path setup

14. Part XIII: Green transmission paths

15. Part XIV: ITMX oplevs

Can we push the mirrors back to keep more clearance?

16. Part XV: ITMY oplevs

17. Part XVI: Place PRM and SRM

18. Part XVII: BS, PRM oplevs

19. Part XVIII: Pre-pump alignment and clearance check

20. Pump down