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H1 SEI

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sheila.dwyer@LIGO.ORG - posted 18:47, Thursday 27 March 2014 - last comment - 10:49, Friday 28 March 2014(11039)

New Seismic untrip instructions

Here is an update on the instruction for untripping seismic, with some new tips from Fabrice, especially for ETMX.

Untrip HEPI WD, use Commands2 window to isolate level 1 on all chambers except BS which is level2

Untrip ISI WD (you may need to raise T240 Threshold)

reset CPS offsets,

go into stage 1 bias screen hit reset CPS offsets, then hit store targets.
Repeat in stage 2 bias screen.

Check that everything is in high gain: (this is also good to check if you are already isolated but have a lot of motion)

Click on the three T240 screens, check that the filter modules labeled gain are ON
In the L4C screen check that the filter modules labeled gain are OFF
in the GS13 screen check that the filter modules labeled gain are OFF

If you have been struggling with switching the blend filters, you may want to zero the T240s. You can do this in the three T240 screens by tuning on the AutoZ filter module in the X filter module, then turning it off.

Use commands, isolate level 3 for most chambers. For ETMX start with Commands, Isolate Stage 1 Level 2. Once this script is finished, isolate stage 2 level 3.

Switch Blends:

Go to stage 2 bleds switch all to Tcrappy. If this failed you can 1st switch Z from Start to Tcrappy, once it has switched RY, RZ, RX, Y, and X.
Wait a long time......until the T240s are have hundreds of counts.
Repeat for stage 2.
There is a switch all button, that might save you from having to do one at a time, but can often trip the ISIs.

good luck...

Comments related to this report

fabrice.matichard@LIGO.ORG - 19:01, Thursday 27 March 2014 (11048)

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We just tried again. The following sequence seems robust for ETMX:

a) Isolate Stage 1 Level 2

b) Isolate Stage 2 Level 3

c) Swith Stage 2 to TCrappy (Using Switch All)

d) Swith Stage 1 to TCrappy (Using Switch All)

We are working on the Guardian to simplify all of this. It will handle all the parameters and sequences specific to each chamber (controls level, blend filters, alignement dofs to be restored...)

hugh.radkins@LIGO.ORG - 07:59, Friday 28 March 2014 (11052)

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It is my understanding that you should NOT zero the T240, certainly not just to try it. In a new installatioin or the T240 is suspected of being out of level, then one should look at the U V W signals and AutoZ if they are not close to zero once the machine has stabilized. Before I was told this, it was my experience that pressing the AutoZ did NOT speed up the Trillium settleing process. Rich Mittleman--please weigh in here.

brian.lantz@LIGO.ORG - 09:37, Friday 28 March 2014 (11055)

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I agree with Hugh that re-zeroing the T240 should not be done while the T240 is in the midst of settling from a large dynamic shift. The re-zeroing is used to reset the mass-center of the instrument. This can shift with temperature or DC level changes. One should be sure the instrument has fully stabilized, otherwise you run the risk of 'recentering' to some off-center location.
the Manufacture's (Nanometrics) instuctions can be found in section 2.4.2 of the T240 OBS manual (1). 
https://dcc.ligo.org/LIGO-T0900323  (2)
-Brian


(1) OBS - Ocean Bottom Seismometer. we use this because it is smaller, and we provide our own pressure vessel.
(2) yes, we have received permission to put a copy in the DCC.

sheila.dwyer@LIGO.ORG - 10:49, Friday 28 March 2014 (11056)

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Thank you for clarifying...

Fabrice asks that we also add a step at the begining of the procedure where we plot the WD trip, zoom in and post it in the alog. Hopefully this we result in seismic people analyzing them and figuring out why we have so many trips.

This is important because our current rate of trips (and the time it takes to recover from them) will be a serious impediment to commsioning once we need to use 7 chambers all at the same time.