Randy T., Camilla C., TJ S.

After the chiller was found tripped off and water was found in the plastic "leak containment apparatus" last week (alog89931), we expected to have to replace the expansion joint as we did in January 2024 (alog75657). Turns out, the expansion joint is okay but the fittings have loosened themselves overtime not just on this line but some of the others as well. More details below.

Today when Randy went to go swap the joint out for a used spare, he noticed that the fittings were very loose, not only on the TCSX supply line, but on a few others. He re-tightened all fittings and we decided to test it out slowly with water. Camilla tried to turn on the chiller, but it would shut itself off saying "low flow". She and I then closed the 3way valve in back which makes the chiller run in a closed loop within the chiller. This worked to get it to run. We then slowly opened that valve to slowly allow water to start flowing down the supply line. Randy was waiting and watching at the joint and never saw any water leaking out during the ~5 min test.

At this point we think that the water just leaked out of the loose fittings when the quick connect was disconnected last week. The updated chiller settings most likely helped and turned off the chiller before the pressure reached levels that could cause damage to the system. We will add checking the tightness to the quarterly pipe check FAMIS task. 

Next steps - start on replacing the TCSX table flex lines, and work on making a unistrut cage around the quick connects to avoid bumps in the future.

TITLE: 04/21 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

Covering the morning Ops shift & handing off to RyanS.
LOG:

• 1431-1553 Technical cleaning @lvea (nellie.kim)
  • 1553-1703  kim will head to  @ex
  • 1553-1630 nellie @my
• 1500-1604 Property inventory checks in livea & optics lab (christina)
• 1547-1552 Checking to see if FARO did an auto-power-up this morning (ryanc)
• 1557-1629 cp1 turbo (new) leak checking (jordan, gerardo)
• 1615-1645 3ifo checks in lvea & then out-bldgs (tyler)
• 1615 FAMIS checks (chris)
• 1619 FARO procedure tests in northbay (jason.ryanC)
• 1628-1645 pipe bridge, tcsx (tj.randy)
  • 1645 TCSy chiller turned OFF (tj)
  • 1645 randy swapping out tcsx expansion joint on piping platform
• 1628 Pcal lab grabbing parts for EY (tony)
  • Went to EY after and was done at EY at 1735.
• 1629-1703 EY annulus pump check (jordan.gerardo)
• 1645 Guardian server work (WP13186) begins with TJ having me taking SEI nodes to desired states (mainly ISI DAMPED HEPI OFFLINE)
  • Eric & TJ beginning guardian server work.
  • 1708 Connection error for many/all guardian nodes
• 1655 h1ioplsc0 restart to try and fix timing errors (dave, W13187); will do a daq restart around 1130.
• 1703 hepi actuator stuff @bsc2 (mitch,jim)
• 1717-1733 return to cp1 turbo (new) leak checking (jordan, gerardo)
• 1720 EY property inventory (fil)
• 1724 Flushing TCSx system test (camilla, randy)
• 1729 Ibrahim looking for randy
• 1739 handing off to RyanS.

Tue Apr 21 10:10:27 2026 INFO: Fill completed in 10min 24secs

WP13186 TJ, Dave, Erik:

10:07 h1guardian1 powered down for OS upgrade to Debian13.

TITLE: 04/21 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 4mph Gusts, 2mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.29 μm/s 
QUICK SUMMARY:

BSC2 work continues, CDS work.  HAM5 & 6 HEPI has been down overnight due to HEPI pump system issues noted yesterday.

Workstations were updated and rebooted.  This was an OS packages update.  Conda packages were not updated.

Madi, Camilla

Started ETMX Ring Heater test for HWS testing, turned up from 1W/segment to 2W/segment. Plan to leave until tomorrow.

TITLE: 04/20 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: Some BSC2 and cabling work done today. HAM5 and HAM6 HEPI are going to be down overnight since the HEPI pump is having issues.
LOG:

In prep for WP13185 to replace the flex lines on the table and the expansion joint, I've drained and vacuumed the TCSX table and then I just used gravity to drain most of the water in the supply line, enough so that the expansion joint is free of water.

WP13182 BRS-EX recovery

Jim, Patrick, Dave

I tried to reboot, but ended up power cycling, h1brsex. Patrick started the code and IOC. Since then it has been attempting to damp over the past few hours.

FAMIS 31134

The ISS diffracted power has drifted down a bit over the past few days, so I'll bring that back up towards 4%. No other major events of note.

Mon Apr 20 10:09:19 2026 INFO: Fill completed in 9min 16secs

TITLE: 04/20 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 9mph Gusts, 5mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.19 μm/s 
QUICK SUMMARY:

BSC2 work today

ETMY SWWD tripped at 01:17 PDT this morning due to an EQ. I have reset the DAC drives.

Sun Apr 19 10:06:23 2026 INFO: Fill completed in 6min 19secs

Closes FAMIS 28639

Last checked in alog 89720

TCSX read 30.8 - nothing added

TCSY read 10.6 - nothing added\

No water in small cup under the slow leak

TCSX is reading HIGH PRESSURE FAULT. See attached picture. 

(Travis, Randy, Gerardo)

On Monday, the -Y door went on the HAM1 chamber with some minor issues not noted on previous installations, for some reason we had two minor misalignments: one, the door did not hung parallel to the HAM's flange,small tilt towards the outside on the upper part of the door, maybe the pick point slid forward.  Two, the door required a clocking move, we pinned two holes spanning 5:12 O'clock, then rotated the door clockwise a bit until all of the holes aligned, then a small movement on the -Z to complete the alignment about 1/8".  After all of that the door looks pretty concentric to the chamber flange.

Something to note, a dirty glove was found inside the chamber, yes inside the chamber under the support tube on the -Y side of the chamber, as I write, I nod, because it does not take much time to get this dirty thing out of the chamber.

From the previous alog post, Sheila measured a power drop across BL2 lens.

Here I modeled the loss of the 700um beam waist across the 2.5mm BL2 lens aperture.

The expression for the transmitted power obtained by modifying the Gaussian beam equation to include a displacement d² = d_x² + d_y² is shown here.

And here's the contour plot for the loss (1-T) across the lens aperture for a beam transversing across various spots on the lens.

Varun, Stefan

We measured the (one-way) SRC Gouy phase to be 28.97deg +-0.11deg (statistical) +-0.43deg (systematic).
We used a method pioneered in KAGRA (klog 9241 and 9246). A similar method was used for the PRC Gouy phase measurement(alog 52504).

Plots:
 - Plot 1: SRC scan across 6 fringes. Blue: AS_C_SUM, Red: AS_C_SEG2 (both derived from IOP channels). Magenta: round trip Gouy phase fit from the two results.
 - Plot 2: Raw data strech of 6 best fringes.

Method:
- Align BS and SRM (in SRY) carefully (especially BS)
- Misalign SRM by 70 urad (we did pos pitch)
- Let SRMI freely swing (i.e. SRM and BS aligned, PRC misaligned)
- SRCL1 and MICH1 gains 0 (we don't need the control loops)
- Put an offset in SRCL2_OFFSET (we used -1e6cts)
- Turn off all whitening on ASC-AS_C
- We want the LSC trigger to fire and stay latched (and apply the offset) when ASC-AS_C reaches the darkest possible spot.
  This corresponds to the BS in the correct position, increasing the finesse of the SRC to its maximum.
- We achieved that with a negative trigger matrix element, a slightly positive enable threshold (since AS_C swing slightly negative), and a very negative disable threshold
  We used: H1:LSC-TRIG_MTRX_4_14 =-100, H1:LSC-SRCL_TRIG_THRESH_ON = 0.015, H1:LSC-SRCL_TRIG_THRESH_OFF = -100
- To read the data we need the highest possible data rate. So in addition to H1:ASC-AS_C_NSUM_OUT we recorded the IOP channels
  H1:IOP-ASC0_MADC6_TP_CH9, H1:IOP-ASC0_MADC6_TP_CH10, H1:IOP-ASC0_MADC6_TP_CH11, H1:IOP-ASC0_MADC6_TP_CH12
- Those IOP channels are before the fixed anti-whitening filter. So we did the anti-whitening filter in diaggui ('zpk([40],[0.4],1,"n")').
- The 4 quadrants of ASC-AS_C saw different combinations of the higher order modes.
- We used SEG4 (CH9) for finding the 00 modes.
- We used SEG2 (CH11) and the sum of all 4 segments for 10 modes (red and blue traces respecively).
- We chose a bank of 6 fringes with very low AS_DC values - those have the highest finesse.
- A spline fit was used to interpolate the time to degrees in-between 00 peaks.
- We calculated the mean from the red and blue traces separately. Their mean is reported as final value.
- We calculated the standard deviation of the mean from the red and blue traces separately. The maximum of the two errors is reported as statistical  error.
- The difference between the red and blue result is reported as systematic error.

The code and raw data is found in /ligo/home/controls/sballmer/20191022.