Displaying reports 6441-6460 of 83386.Go to page Start 319 320 321 322 323 324 325 326 327 End
Reports until 12:21, Friday 19 July 2024
H1 SQZ
camilla.compton@LIGO.ORG - posted 12:21, Friday 19 July 2024 - last comment - 16:12, Friday 19 July 2024(79246)
SQZ, SRM and PSAMs back to last last bad spot alignment

Vicky, Camilla

Took ZM4,5,6, SRM alignment and PSAMs back to their values on 2024/07/17 20:18 to 20:23 UTC as in 79193. Plot here. We hope this will allow the SQZ beam through the OFI.  SDFs for ZMs attached but not saved (incase we want to revert them if SQZ beam not seen), SRM optical align alignments were 2240, -3436 before as not svn monitored.  SRM WD was tripped, Tony reset this.

SQZ OPO is seed dither locked but I can't see the most of the beam power on the SQZT7 diode. Vicky pointed out I should use the RLF QPDs to check for FC1, ZM1,2,3 pointing, they looked bad but there was some light on the QPDs, moved alignment sliders to get the FC1, ZM1,2,3 osems to be the same as 2024/07/17 20:18 to 20:23 UTC. This made the beam completely off the QPDs so I reverted, plot and sdf attached. We started walking the beam with FC1 and ZM3 as in 75509. Then Daniel asked if we had the TECs on...d'oh. after the TECs were turned on we had the QPDs saturating and I reverted all ZM1,2,3 and FC1 changes.

After lunch: Can reduce SEED power and check centering on QPDs. Can open SQZT7 and check the beam is going though the irises.

Images attached to this report
Comments related to this report
camilla.compton@LIGO.ORG - 16:12, Friday 19 July 2024 (79248)

Jennie, Camilla, Naoki, TJ

Put SEED back to 75mW, IR PD still had 0.79mW (expect (1.3mW), we tried reverting ZM4,5 to the values this morning, before I corrected for the vent, this dropped the power further.

Only 0.7mW was making it to SQZT7. We dropped SEED power for  75mW to 5mW, started well centered on QPDA but -0.7 off QPDB_PIT, plot. We moved ZM3/FC1 to improve this to 0.88mW . We are normally +0.3 off in PIT, see attached. Later, once we were on SQZT7, Naoki noticed that this alignment wasn't good enough as SK beams were not co-aligned.  Photo attached.

On SQZT7 we used ZM4 to align to first iris and ZM5 to align to second iris, now H1:SQZ-OPO_IR_PD_DC_POWERMON increased to 0.96mW, still now 1.3mW we're expecting. Opened Beam divertor, TJ then checked that the SQZ beam was making it to SRM and back through the OFI!  We can even see SQZ light on AS_C, plot attached. Not easy to take a photo of the beam on the KTP yet.

The SQZ alignment we liked is attached, sdf'ed and was what we had at 2024/07/19 23:00UTC.

Next week, we can decide to keep this alignment or improve the SK co- alignment and realign ZM4,5 path. We should then take our set of power measurements through the OFI/SRM.

Images attached to this comment
H1 CAL (CAL)
dripta.bhattacharjee@LIGO.ORG - posted 10:52, Friday 19 July 2024 - last comment - 09:37, Tuesday 23 July 2024(79244)
PCAL EY End Station Measurements on Thursday, 18th July, 2024

Rick Savage, Dan Chen, Shingo Hido, Emmanuel Makelele and Dripta.

 

We went down to EY on Thursday, July 18th, 2024 to do a Pcal measurement, mostly to show the measurement procedure to our visitors. We used the procedure outlined in T1500062-V17 as a guide. A scanned copy of the filled out measurement procedures and log is attached.

Before we began the measurement, a picture of the beam spot position was taken. It shows that the beams were centered on the Rx sensor apreture (BeamSpotBefore photo attached).  

As noted in the scanned copy, after the first background measurement while WS was placed in the Tx module, the shutter stopped working. We could not open the shutter locally or remotely. The shutter has now been removed from the EY Tx module for troubleshooting. Pictures attached.

We continued with the measurement manually shuttering and unshuttering the laser. After taking all the measurements, a beam position picture was taken. It shows that the bemas remained centered and the Pcal beam spots did not drift significantly during the measurements (BeamSpotsAfter photo attached). 

Analysis and results/plots to follow. 

 

Images attached to this report
Non-image files attached to this report
Comments related to this report
dripta.bhattacharjee@LIGO.ORG - 09:37, Tuesday 23 July 2024 (79281)

The analysis and report can be found in git: https://git.ligo.org/Calibration/pcal/-/tree/MergingBranch/O4/ES/measurements/LHO_EndY/tD20240718?ref_type=heads

The report LHO_EndY_PD_ReportV3.pdf shows that the latest Rx reponsivity measurement is within 5 hop (hundredths of a percent) of the mean value and the optical efficiency is within 10 hops of the mean optical efficiency value. 

 

 

H1 CDS
erik.vonreis@LIGO.ORG - posted 10:30, Friday 19 July 2024 (79245)
cdsadmin

Conda packages updated on workstations.  diaggui was updated to version 4.1.3, fixing a bug in  excitation channel name nesting that could cause the excitation channel selection box to inadequatly nest channel names.

H1 General (Laser Safety, Laser Transition, OpsInfo)
anthony.sanchez@LIGO.ORG - posted 10:22, Friday 19 July 2024 (79243)
LVEA LASER HAZARD Transition

TJ has Transitioned the LVEA into LASER HAZARD for Work Permit:

https://services2.ligo-la.caltech.edu/LHO/workpermits/view.php?permit_id=11988
LHO VE (VE)
gerardo.moreno@LIGO.ORG - posted 09:45, Friday 19 July 2024 - last comment - 17:03, Friday 19 July 2024(79242)
Corner Station Dew Point Measurement

This morning I took a dew point measurement of the corner station purge air at the purge valve for the output mode cleaner tube, the following chambers were using the purge air, HAM5 with two soft covers on, and HAM6 with one soft cover.  HAM7 was not drawing any purge air.

Dew point measurement is -41.5 oC.

Images attached to this report
Comments related to this report
gerardo.moreno@LIGO.ORG - 17:03, Friday 19 July 2024 (79255)VE

And attached is the end of the day measurement.  Dew point of -43.2 oC.

Images attached to this comment
H1 ISC (IOO, SYS)
camilla.compton@LIGO.ORG - posted 08:49, Friday 19 July 2024 - last comment - 09:35, Friday 19 July 2024(79237)
Initial HAM6 Inspection: New discoloration on Fast Shutter

Sheila, Betsy, Camilla

With the HAM6 +X door off we did an initial inspection of HAM6, looking for anything that could have caused the pressure spikes seen in 7834678432

There was discoloration on the fast shutter, see lower half of the -X part of the "fast shutter cap" and viton piece: part (4) and  (10) of D1003318. Photos attached.  This was the only thing we could see out of the ordinary. 

From the Feb 2024 HAM6 closeout photos in 75791, this photo shows the fast shutter and no discoloration can be seen. 

We'll plan to inspect the fast shutter when closed today.

Images attached to this report
Comments related to this report
corey.gray@LIGO.ORG - 09:35, Friday 19 July 2024 (79241)EPO

Tagging for EPO.

LHO VE
david.barker@LIGO.ORG - posted 08:07, Friday 19 July 2024 (79233)
Fri CP1 Fill

Fri Jul 19 08:04:09 2024 INFO: Fill completed in 4min 6secs

Gerardo confirmed a good fill curbside.

Images attached to this report
H1 General
anthony.sanchez@LIGO.ORG - posted 07:39, Friday 19 July 2024 (79232)
Friday Ops Day Shift Start

TITLE: 07/19 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Ryan C
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 8mph Gusts, 5mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.11 μm/s
QUICK SUMMARY:

IFO currently DOWN for maintenace.
LVEA is currently LASER SAFE
Temps in the LVEA have come back down from their peak yesterday.

Expected work today (according to DCC Doc E2400260) :

H6 - Initial inspection of OM1, Refl Beam dump, cables, PDs, beam dumps, etc
H5 - Lock ISI
H5 - Remove OFI Black glass panel shroud pieces from at least +X side and roof.  TAKE CARE TO INVESTIGATE any clipping or anything out of nominal.
Remove HAM6 -X DOOR
H6 - Lock ISI
Pull CC wafers reachable in both chambers
H5 - Initial inspection of OFI and SRM optic surfaces, cables, beam dumps, etc
FTIR sample XX areas on table and around any damage areas (5 sample vials).
H5 - Transition to Laser Haz
Setup AUX laser systems, prioritize HAM5 alignment laser

 

Images attached to this report
H1 AOS (SEI)
neil.doerksen@LIGO.ORG - posted 20:18, Thursday 18 July 2024 - last comment - 09:31, Tuesday 01 October 2024(79231)
Dominant Axes During EQ Lockloss

Edit : Neil knows how to make links, now. Tony and Camilla were instrumental in this revelation.

This is an update to my previous post (Neil’s previous post on this topic) about looking for possible explinations why similar seismic wave velocities on-site may or may not knock us out of lock.

The same channels are used in addition to:

SEI- * ARM_GND_BLRMS_30M_100M
SEI- * ARM_GND_BLRMS_100M_300M
Where * is C, D, X, or Y.

I have looked at all earthquake events in O4b, and only ones which knocked us out of lock. This is to simplify the pattern search, for now. Here are the results.

Total events : 29

Events with ISI y-motion dominant : 11 (30-100 Hz) : 8 (100-300 Hz)
Events with ISI x-motion dominant : 3 (30-100 Hz) : 0 (100-300 Hz)
Events with ISI z-motion dominant : 9 (30-100 Hz) : 19 (100-300 Hz)

Events with ISI xy-motion dominant : 1 : 0 (Both axes are similar in amplitude.)
Events with ISI yz-motion dominant : 0 : 1
Events with ISI xz-motion dominant : 0 : 1

Events with IS xyz-motion dominant : 5 : 0

Total SEI- * ARM recorded events : 8
CARM dominant events : 7 : 8
C/XARM dominant events : 1 : 0

Conclusion is that in the 30-100 Hz band, it is equally likely to have either z- or y-axis motion be dominant. In the 100-300 Hz band, the ratio is about 1:2 for z and y motion being dominant during lockloss.

Clearly, common modes are a common (^_^) cause of lockloss.

Note that velocity amplitudes should be explored more.

Comments related to this report
neil.doerksen@LIGO.ORG - 09:31, Tuesday 01 October 2024 (80394)

NOTE : All units are in mHz, not Hz.

LHO VE
janos.csizmazia@LIGO.ORG - posted 19:29, Thursday 18 July 2024 (79230)
7-18 vent vacuum diary
Today's activities:
- The purge air dew point was measured at the purge port: (9:15 am) -42.5 deg C
- The relay tube was vented with Nitrogen, and was taken off: at the HAM5 side, the dog leg stayed, and at HAM7, one bellows was left there
- The HAM5/HAM6 annulus system was vented with Nitrogen, the AIPs have been turned off
- HAM5+X, HAM5-X, HAM6+X doors have been removed. Both HAM5 doors' inner O-ring are needed to be replaced, as they are damaged and worn out
- IP19 was valved out at the top of HAM7
- HAM7 was vented, but all doors are staying in place for now
- The pressures outside the corner have been stabilized now, and consistently dropping

The pressures:
- Corner, HAM7: atmosphere
- Y-manifold: 3E-8 Torr
- CP1: 3.9E-9 Torr
- CP2: 5.3E-9 Torr
H1 SUS (ISC)
thomas.shaffer@LIGO.ORG - posted 16:50, Thursday 18 July 2024 - last comment - 09:33, Friday 19 July 2024(79227)
OFI shroud partially removed

Mitchell R, TJ S.

We removed the one +X panel, three of the top panels, the +Y panel, and one on the -X side. This should give enough room to work on the OFI below and get power meters into all places needed.

Some panels had minor blemishes on them, I'll have to reference the photos we took when installing to make sure they aren't new.

Dust counts when entering chamber were 0's or 10. They were checked periodically with similar readings.

Images attached to this report
Comments related to this report
corey.gray@LIGO.ORG - 09:33, Friday 19 July 2024 (79240)EPO

Tagging for EPO.

H1 SEI
jim.warner@LIGO.ORG - posted 16:39, Thursday 18 July 2024 (79047)
HAM8 H1 GS13 troubleshooting, bad shield connection edition

On a Tuesday a couple weeks back I went to HAM8 and looked at connections between the shield pins for all of the single axis seismometers on HAM8, both at the rack and at the feedthru on the chamber. For the H1 seismometer I found that pin 9 (labeled as GS13-2 Sig+ on D1002706) is grounded to pin 5, which is the shield, this would explain why the sensor has a gain of 1/2 compared to the other seismometers. None of the other GS13s show this shield connection to signal. However, 2 of the L4C pairs have multiple wires connected to the shield, I haven't run down what they are yet. All of the wires that are connected to shield are connected at both the rack and the flange, so the issue is somewhere in vacuum. Can't really tell more at this point without opening the chamber. I plan to check HAM7 at some point, but that is a borrow from 3ifo.

Mitch and I did some tests on what spare A+ cables we could find in the staging building, 2 D1000227 pigtails and 2 220(?) 25pin extensions. We couldn't find or cause any connections between the shields and signal wires, but it wasn't an exhaustive test. I'm also huddling some GS13s on the table, I will try to see if there are any wire-shield connections with the cables that are plugged into those sensors.

LHO General
ibrahim.abouelfettouh@LIGO.ORG - posted 16:34, Thursday 18 July 2024 (79226)
OPS Day Shift Summary

TITLE: 07/18 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY:

IFO is in CORRECTIVE MAINTENANCE for VENTING

Productive day where we found the culprit (yet to be seen if there are more) to our OFI issues in the form of a burn on the KTP Optic of the OFI (alog 79223). After this point, there were impromptu meetings discussing how to proceed. A slight shift of priorities was announced and the check-list is as follows (E2400260):

WED JULY 17

  1. ✅ Check that after HEPI locking SQZ and single bounce beams both go to AS_C, find SRM and SR2 slider values to simulate alignments from early April and from June.
  2. ✅ Check ITM OPLEVs
  3. ✅ Close GV1,2sheila.d, FC tube GVs
  4. ✅ Vent Corner, HI Volts on/off, see their M-doc. Full laser Safe transition. 

THUR JULY 18

  1. ✅ Vent and Remove Relay tube
  2. ✅ Remove Cameras from HAM6 door (alog 79213)
  3. ✅ Open HAM5 via  +X DOOR
  4. ✅ Open HAM6 via  +X DOOR
  5. ✅ Vent HAM7
  6. ✅ HI VOLT BYPASS back on (alog 79222)
  7. ✅ Remove HAM5 -X DOOR
  8. H6 - Initial inspection of OM1, Refl Beam dump, cables, PDs, beam dumps, etc
  9. H5 - Lock ISI
  10. H5 - Remove OFI Black glass panel shroud pieces from at least +X side and roof.  TAKE CARE TO INVESTIGATE any clipping or anything out of nominal.

FRI JULY 19

  1. Remove HAM6 -X DOOR
  2. H6 - Lock ISI
  3. Pull CC wafers reachable in both chambers
  4. H5 - Initial inspection of OFI and SRM optic surfaces, cables, beam dumps, etc
  5. FTIR sample XX areas on table and around any damage areas (5 sample vials).
  6. H5 - Transition to Laser Haz
  7. Setup AUX laser systems, prioritize HAM5 alignment laser 
  8. Using SQZ beam delivered from HAM7, make OFI Measurements in-situ:
    1. Measure loss after each component inc. SRM with power meter. 
  9. Transition back to Safe when done.

Aditionally, all TFs for pe-vent suspensions have submitted ALL_TF and comparison TF reports as comments to their initial alogs: alog 79189, alog 79188, alog 79198, alog 79202

These plans are of course tentative and depend on ongoing decisions in this living (and breathing) document. Well done to the quick, efficient and safe vent crew!

THIS JUST IN: Approximately 3s before hitting enter, the vent crew came back with more pictures of backsplashed debris from the two burn spots in the OFI. Stay tuned for more (alogs).

LOG:

Start Time System Name Location Lazer_Haz Task Time End
14:48 FAC Karen, Kim LVEA N Technical Cleaning 15:48
15:53 EE Fil, Camilla LVEA N Pulling off HAM6 Cameras 16:53
16:10 FAC Chris, Eric HAM6 N Breaking torque on HAM6 Door Bolts 19:20
16:12 FAC McCarthy HAM6 N Ensuring Safety during door work 18:12
16:14 FAC Bubba G EX & EY N Resuppling First Aid Kits 17:26
16:16 VAC Jordan, Tyler HAM6 N HAM6 Door Bolt Torque breaking 19:38
16:18 VAC Travis, Gerardo LVEA N Relay tube VAC work & HAM6 Door crew work. Travis out 19:15UTC 19:31
16:31 FAC Tyler FCES N Camera Acquisition 16:52
16:33 VAC Jason LVEA N Aux lasers for LVEA vent team 16:42
16:44 EE Keita LVEA N Fil BNC Cable HAM6 17:10
16:57 FAC Kim, Karen LVEA N Technical Cleaning 17:57
16:58 FAC Fil LVEA N Interlock 17:58
17:11 SQZ Keita, Jennie Optics lab Local Work on HAM5/6 laser 19:38
17:23 SQZ Camilla Optics lab Local Check if team has all the parts they need 18:40
17:45 CAL Tony PCAL lab LOCAL Gather stuff 18:03
18:41 SQZ TJ Optics Lab Local Part search Part 2 19:08
18:41 FAC Richard LVEA N Supervision 19:01
18:42 PCAL Rick, Guest LVEA N Walking Tour 19:20
19:05   Betsy LVEA N Check on crew 19:25
19:39 EE Fil CER N ISI WD Cable Reset 20:28
19:43 PCAL Rick, Dripta, Emmanuel, Shingo, Dan EY YES PCAL Measurements 21:54
20:23 FAC Tyler LVEA N HAM5 -X Door Removal Prep 21:51
20:28 VAC Chris, Jordan, Travis LVEA N HAM5 -X Door Removal 21:51
21:32 SUS Mitchell, Betsy, TJ, Sheila LVEA N HAM5 Door + OFI 23:32
22:26   Oli LVEA N Parts dropoff 22:30
22:42   Ibrahim LVEA N Sensor calibration 22:45
23:28 PCAL Tony, Emmanuel PCAL Lab Local LHO PS4 PS5 Measurement 00:28
H1 SUS (SUS)
rahul.kumar@LIGO.ORG - posted 16:18, Thursday 18 July 2024 - last comment - 09:32, Friday 19 July 2024(79224)
Magnet-standoff assembly bonded to SRM-07 (HSTS spare optic)

Spare optic SRM07 arrived at LHO yesterday from LLO, after prisms were bonded to it's sides (see LLO alog 71969 for details). After inspecting the optic in bonding lab, I started preparing for bonding the magnet-standoff on the AR side. At first I prepared 8-10 magnet-standoff of both north and south polarity. The magnets were glued to the standoffs using Masterbond EP-30 - as per assembly drawing D0902432_V2.

The optic with AR side facing up (arrow at the top of the optic points towards the HR side) was placed on the gluing jig and aligned with the scribe lines. Once the edge of the optic was well aligned with the jig, metal plungers with the magnet-standoffs were inserted inside (the jig) - after applying the Masterbond EP-30 to the bottom tip of the standoffs using a pin (for reference see pic here). This set up was left for curing for 24hrs approximately, following which the jigs were removed. Given below are the details with pictures for reference,

- SRM07 arrived at LHO in pelican case - image01.

- optic inside the transport can - image02

- optic placed on the optical bench for inspection - image03

- Metal jig were placed on top of the AR side of the optic and aligned with the scribe lines and the optic edge (locked with stops having silica tip ends)- image04

- magnet-standoffs with plungers inserted into the jigs - image05

- magnet standoff prepared in lab - image06

- jigs removed and SRM07 with magnets glued to its AR side is visible - image07 and image08

- Optic with labels showing the four magnets and their polarity - image09 - see controls arrangement poster for reference.

Images attached to this report
Comments related to this report
corey.gray@LIGO.ORG - 09:32, Friday 19 July 2024 (79239)EPO

Tagging for EPO.

H1 AOS (IOO, ISC, SYS)
betsy.weaver@LIGO.ORG - posted 14:26, Thursday 18 July 2024 - last comment - 09:31, Friday 19 July 2024(79223)
Quick inspection of the first OFI comonents visible as the door came off

Looks like there is visible damage on the KTP optic of the OFI.

 

TBC...

Images attached to this report
Comments related to this report
camilla.compton@LIGO.ORG - 17:11, Thursday 18 July 2024 (79228)IOO, ISC, SYS

Betsy, Sheila, TJ, Mitchell, Camilla

On second inspection, after TJ and Mitch removed some of the OFI shroud 79227, you can clearly see two crater holes in the KTP wedge on the input (SRM) sideG2100316 OFI doc. The output (OMC) side of the KTP wedge looked smooth. Photo and photo. 

There is splatter on the Fused Silica wedge optic, holder and surrounding beam dumps facing the KTP crater holes. Photo and photo. Maybe there was more splatters on the KTP holder too.

Photos of the SRM AR surface looked fine, but it was hard to see: photo

Zoomed out photos of the OFI with shroud removed to aid with planning: here and here. 

Additional photos from everyone on googledrive here. 

Images attached to this comment
camilla.compton@LIGO.ORG - 08:37, Friday 19 July 2024 (79234)

Attached is a view looking through the OFI from the SRM side back towards HAM6. As well as the two crater spots, you can see the black dots of splatter on the FS wedge. 

Images attached to this comment
corey.gray@LIGO.ORG - 09:31, Friday 19 July 2024 (79238)EPO

Tagging for EPO.

H1 SQZ (ISC, SQZ)
jennifer.wright@LIGO.ORG - posted 14:10, Tuesday 16 April 2024 - last comment - 19:04, Thursday 18 July 2024(77204)
OMC Scan with PSL beam

Jennie W, Sheila,

 

We turned off the 9 and 45 MHZ sideband EOMs and unplugged the 118 MHz modulation at the PSL racks. See this alog for how to do this.

 

We locked the IMC and mis-aligned ITMX.

 

DC centering loops 3 and 4 were turned on.

 

Sheila took the OMC lock guardian to PREP OMC scan and turned on the OMC ASC.

We waited for this to converge then turned it off.

 

We turned input power up to 10W from 2W and then locked the OMC in length manually by using the PZT offset slider to search for a high peak ~ 15mA.

After finding it we turned on the locking with a gain of 24 and the boost and int filters on (we checked the settings we needed in the guardian as we couldn't get the OMC guardian to lock it for us).

 

Then we turned off the OMC ASC.

 

We tuned up the OM3 and OMC alignment slightly to maximise the power on OMC-DCPD_SUM_OUTPUT and minimise it on OMC-REFL_A_LF_OUT16.

OM3 was moved down in yaw only from -108 to -117 and OMC was moved down in yaw from 210.5 to 195.5 and down in pitch from 350.4 to 340.4. The final values for the sliders are here.

 

Quiet time locked after aligning 16:21:03 UTC - 16:24:13 UTC

OMC-REFL_A_LF_OUT16 = 0.652644 mW

OMC-DCPD_SUM_OUTPUT = 15.6162 mA

 

Quiet time unlocked 16:25:31 UTC -16:27:35 UTC

OMC-REFL_A_LF_OUT16 = 30.106 mW

OMC-DCPD_SUM_OUTPUT = 0.000456763 mA

 

We took the IMC guardian offline and shuttered the green light going into both arms at the ISC tables, and with ISC_LOCK guardian in idle so it wouldn't keep trying to relock IMC.

Quiet time dark measurement 16:43:38 - 14:46:19 UTC

OMC-REFL_A_LF_OUT16 = -0.0132979 mW

OMC-DCPD_SUM_OUTPUT = -0.00106226 mA

 

The scan template is saved as /ligo/home/jennifer.wright/Documents/OMC_scan/2024_04_16_OMC_scan.xml

With the references for the time series of the three pertinent channels as:

Ref 0 OMC-DCPD_SUM_OUT_DQ

Ref 1 OMC-PZT2_EXC

Ref 2 OMC-PZT2_MON_DC_OUT_DQ

 

Images attached to this report
Comments related to this report
jennifer.wright@LIGO.ORG - 19:01, Monday 06 May 2024 (77670)

I ran Sheila's code from this entry, altered with the measured input/output coupler transmission of the current OMC which can be found on Page 116 on LIGO-T1500060.

The output gives this for the cavity parameters:

Power on refl diode when cavity is off resonance: 30.138 mW

Incident power on OMC breadboard (before QPD pickoff): 30.589 mW

Power on refl diode on resonance: 3.879 mW

Measured effiency (DCPD current/responsivity if QE=1)/ incident power on OMC breadboard: 59.5 %

assumed QE: 100 %

power in transmission (for this QE) 18.203 mW

HOM content infered: 9.763 %

Cavity transmission inferred: 66.439 %

predicted efficiency () (R_inputBS * mode_matching * cavity_transmission * QE): 59.509 %

omc efficency for 00 mode (including pick off BS, cavity transmission, and QE): 65.948 %

round trip loss: 3504 (ppm) Finesse: 335.443

 

I will cross-check the HOM content inferred by analyaing the C02 mode height from a cavity scan.

jennifer.wright@LIGO.ORG - 19:04, Thursday 18 July 2024 (79229)

The mode-matching inferred from the height of the carrier 02 mode vs. the carrier 00 mode from the scan is 0.0983 mode mis-match = 9.83%.

The mode scan fit and the C02/C20 fit are attached.

The code is on labutils /dev branch

The code for the full scan can be ran using:

python OMCscan_nosidebands9.py 1397320410 80 "Cold OM2, 10W PSL, pre-output loss" "single bounce" --verbose -m -o 2

The code for the C02 fitting can be done using:

fit_two_peaks_no_sidebands9.py

Where the blue trace is the data, the orange is the fit, and the purple is the function plotted with the inital guesses for the fit parameters as a cross-check.

Non-image files attached to this comment
Displaying reports 6441-6460 of 83386.Go to page Start 319 320 321 322 323 324 325 326 327 End