Reports until 19:48, Saturday 07 July 2012
H2 SEI
matthew.evans@LIGO.ORG - posted 19:48, Saturday 07 July 2012 - last comment - 06:06, Monday 09 July 2012(3360)
EY ISI not isolating - bias added to RZ

The EY ISI was also tripped.  I reset it, so we have damping, but I don't know the secret handshakes for turning on the isolation, so we will live without.

I added an offset to the input of the ST!-ISO_RZ filter bank, turned off the Cont_1 filter, and set the output gain to 200.  This results in essentially no alignment bias for ETMY and TMSY.  Of course, the isolation won't work like this, but I couldn't find any other way to bias the alignment of the ISI.  SEI team: please make this right!

Comments related to this report
matthew.evans@LIGO.ORG - 14:25, Sunday 08 July 2012 (3366)
Link

Having figured out how to reset the HEPI watchdog, I moved the RZ bias to HEPI.  In the process I discovered that the HEPI DC Biases have no ramps or filters, so they are pretty disruptive.  This lead me to use the ISC YAW filter offset (mislabeled V).  Here I discovered that the HEPI ISC paths are not in the order speciied on the screen, so I have to send my offset to RX to get RZ.  Furthermore, we seem to still have the "poor choice of calibration units" problem, since the offset needed to make 14k counts on the H sensors was greater than 106.

The ISI settings are now as before.  Note: we have no isolation on either ISI just damping.

fabrice.matichard@LIGO.ORG - 06:06, Monday 09 July 2012 (3367)
Link 

Matt,

on IY, the ISI controls are already designed and installed. To Turn it on: in the ISI screen, there's a button called "Commands", which opens a screen with turn on buttons called "Damp Sage 1", "Isolate Stage2", "Isolate System"... 

on EY we have been giving priority to HEPI commissioning (sensor correction) over ISI feedback loops. My understanding was that "ISI Damping + HEPI sensor correction"  would also be a good state for the OAT commissioning. We can certainly change priority (focus on ISI feedback and come back to HEPI Sensor Correction later on). Just let us know what's best for you.