I noticed a pressure "bump" at Y-end recently and have now confirmed that the ion pump mounted at BT port Y2-8 has been off for the past few days.  Today's troubleshooting including re-enabling the High Voltage output.  This resulted in power limited (700V @ 0.5 amp) energization (no ion pumping while inadequately energized).  Next, the HV cable was moved to he other HV channel with a similar result.  The controller-end of the HV cable was disconnected and a VOM used to measure the cable+pump resistance (2.5 Mohm, insufficient output voltage of the meter makes this test "almost" useless).  The HV cable was reconnected to the controller and the pump-end disconnected. In this configuration, the controller wouldn't output HV as the cable connector shield wasn't grounded and, it would seem, the cable isn't shorted.  

I noticed that the pump-end of the HV cable was noticeably "warm" after applying 700V at 0.5 amps.  This observation combined with the interpretation that the cable or pump-end connector aren't shorted indicates that the low resistance is internal to the pump itself.  Ahhh!  The fabled "whisker" theory.  

Monday, we will adapt a custom HV cable and use the "Big Gun" 10,000V 600 watt power supply to, hopefully, vaporize any troublesome whiskers that have formed between the electrodes.  

(Peter K, Gerardo M)

New OFI table is suspended in cage, some components on the cage assembly were loose, they were re-torqued.  The missing corner bracket was installed, and we replaced a couple of bad 1/4-20 flat head socket head cap screws.

Next, table balance and suspension damping.

J. Kissel, C. Vorvick

I've processed the data from last week's first B&K adventure into HAM2 which included the HAUX (a.k.a. HAM Auxiliary Suspensions, a.k.a. IMs or Input Mirrors) (LHO aLOG 39096). 

Recent efforts tightening and torquing the cage bolts to spec (e.g. LHO aLOG 38808) has helped increase the resonance frequencies and Qs of the first bending modes of cage to ~170 Hz in Longitudinal and 220 Hz in Transverse.

These modes are significantly better* than those at L1. 
*Here, by "better" I mean well-defined, high resonance frequencies, and features are similar between suspensions.
The data I use from LLO is the same as posted in LLO aLOG 3948 for IMs 1,2, and 4 from their 2012 vent, and the more recent LLO aLOG 25919 for the problematic IM3 from 2016. 

After discussing with Cheryl, there are several differences that elucidate this difference. 
(1) While LLO has used the "IO" dog clamps of several varieties (D1100640), LHO has used the champhered-ended "SUS" dog clamps (D1100641). These create a more well-defined contact point. 
(2) In addition, the layout of dog clamps around the base of the cage is significantly different; LHO revised the original layout, seeing how unstable the originally prescribed appeared. See table below for comparison of layouts:

Current   Former      Original    Revised
Name      Name        Layout      Layout
                      (LLO)       (LHO)
IM1       SM1         D1200623    T1400742
IM2       PMMT1       D1200625    T1400743
IM3       PMMT2       D1200626    T1400744
IM4       SM2         D1200624    (not revised)

Further confirming the difference -- IM4's clamping configuration does use the IO clamps, in a similar arrangement, and the frequency responses of the cage between H1 and L1 look quite similar -- in Longitudinal, but Transverse remains quite different.

In light of this data, I propose two things:
(1) At the earliest convenience (if there is still such convenience left), we should ECR Cheryl's improvements, implement them at LLO, and update documentation such that India gets similar benefit.

(2) Now that we've stiffened up the resonances, they've become higher Q. We should consider shoving some viton in between the suspension cage, and, say, each of its black-glass cage baffles. It shouldn't need much.

Day's Log Of Activities:

• 14:50 Cleaning Optics Lab (Peter K)
• 15:20 Multiple CER visits (Ed)
• 15:43 - 16:22 LVEA Cleaning (Christina, Vanessa)
• 15:30-15:40 Squeezer Bay & Optics lab visit (Corey)
• 16:00 HAM4 ISI Damping close out (Hugh)
• 16:10-16:35 Swedish TV Crew tour (Vern)
• 16:20 ITMx work in Beer Garden (Travis, Betsy)
• 16:49 HAM2/3 IO work (Cheryl)
• 18:40 HAM2 B&K-extravaganza
• 18:45 (2) 5th Grade Tours led by Elizabeth & Amber
• 19:08-21:11 BSC1/2/3 Work (Robert)
• 19:15-19:46 TCS Table work (Greg)
• 20:27 ITMx work continued (Betsy & Travis)
• 20:42 Checking EY Ion Pump (Kyle)
• 21:20 Optics Lab work (Gerardo)
• I see the Swedish Film duo taking shots with a camera on the hood of their rental. 

Never closer.  Another day in the tank aligning the ITMX main and reaction chains to the oplev, while simultaneously keeping all 132 potential mechanical interferences clear.  COB right now and we have something still rubbing.  Boo.

Also, the ITMY is mechanically rubbing somewhere too.  More next week.

All Corner Station H1 ISI Coil Driver chassis were removed from their racks and modified in trhe EE lab as per ECRs E1100821 & E1300535 .   These mods also include the swapping of a wire on the temp reset switch from the "normally closed" position to the "normally open" position. Also, a number of the surface mount +15VDC indicator LEDs were installed incorrectly and would not illuminate.

Chassis S1103566 in SEI rack C1 doesn't have the "keyed" 24VDC connector. It has the typical +/- 18VDC config and associated power cable.

Chassis S1103363 (HAM2) in SEI rack C2 was noted as having a -15V led not illuminated. Upon further investigation it was found to have a bad 7915 regulator which is what E1300535 was implemented to prevent.

All chassis were re-installed and are powered up. SEI team was informed. E-travelers will be updated.

Finished the last installs of the WHAM4 damping material: the C1 TMD & access walls & table top masses, the C2 V GS13 can and the C3 H GS13 can damping bands.

This was the last WHAM ISIs needing damping installs.  A few photos below for the archive.  Bonus photo feature: included in C1 is the Flexure Damping 'Lantern'!

Snapshot has alignment offsets for all IMC mirrors and IM1 and IM2 in the positions that produced a flashing IMC and a level centered beam to the FI.

We've been working on realignment of the ITMX QUad suspension for a few days now.  However, we continued to suffer from some low vertical on the right side of the reaction chain (viewed from back) which was strange since it is the side that did not suffer the broken wire.  Sometime between alignment a few days ago and yesterday the right side sagged ~1-2mm and was mechanically grounding on the non-adjustable UIM side stop.  While diagnosing this, we discovered that the left side wire (which we had replaced from the break) was an older version and was too long.  So, we embarked on making new wire segments in the staging building, resurrecting the jig, an o-scope and everything associated with it.

This afternoon, we replaced both top-to-UIM wire segments of issue with the newly fabb'ed ones.  This involved a good WIHA tool and all of the extra catch trays installed on the QUAD in order to do the fussy upside-down-one-handed install of the wire clamps screws.  A few hours later and we have the whole ITMx suspended again.  We are still low on the right side, but at least we are not mechanically grounding.  This QUAD always had a bit of a mis-roll counter to the main chain, so likely the full issue is at the very top stage.  New TFs in the coming days will tell us if it is back to "good enough".

Upon inspection of the removed right side wire segment, we see a faint hint that *maybe* just maybe this segment of wire slipped in the clamp (the previously bent ends are straightened out flat, while they are still bent on other segments installed).  This could have occured during the standard, yet jarring realignment last week.

Betsy/Travis

Morning Meeting

• 13:40-15:55 In Optics Lab (Peter King)
• 16:00 West Bay to look for Baffle tooling (Thomas)
• 16:14-17:57 TMD Assy in optics lab (Jeff)
• 16:20 Putting some HAM4 ISI doors on (Hugh)
• 16:31 Baffling work (moving stuff from HAM2 to HAM5 & installing HAM5 baffles) [Steven, Jim]
• 16:40 CER Work (Ed)
• 16:40 Dust Monitor HAM4 reboot (Ed)
• 16:45-18:18 MY Cryopump visit (Rakesh, Arnab, Kyle, Chandra)
• 16:47 Heading to HAM5 to talk to Steven (Gerardo)
• 16:47 ITMx work (Betsy, Travis)
• 17:39 Snow Valley crew for bubba
• 18:39 LVEA Tour For Swedish guests
• 20:45 Barish interview in Control Room begins.
• 20:30 EY Beckhoff went down, required a few reboots at EY (Dave) & then restart by Patrick.
• 21:19 OFI work (Peter & Gerardo)
• 21:28 Continuing ITMx work (Betsy & Travis)

Attached are the BRSx/y drifts.  Signals are fairly flat and NOT in the RED.

This time the IOC stopped running altogether.

Dave has gone to end Y to restart the computer in the hope that this will help alleviate the issue.

Corners 2 & 3 have their newly tuned TMDs installed and the access walls replaced.  Need to do the same on Corner1 and the install the East & West GS13 damper bands--all in chamber work.

Meanwhile, the SR2 and HWS optics can be returned to their locations.

J. Kissel

H1 ISI HAM4's tuned mass dampers have been retuned to match the first bending mode of HAM ISI blade springs post spring-tip-damper install (~139 Hz). Attached are the results for all three TMDs (pg. 1: before and after tuning; pg. 2: after tuning, compared against the blades).

Corner 2 and 3 of the retuned TMDs have been re-installed by Hugh shortly after this data was taken, Corner 1 will come a bit later. Pictures to come.

Details of the measurement setup are as described in LHO aLOG 38741.

Apparently, DM4 stopped responding approx 24 hours ago. It was reset at approx 16:55UTC.