Matt, Trent, Jennie W , Sheila, Craig, Elenna
Executive Summary:
- We found that the new scan indicates the OMC may have new mode spacing between sagittal and tangential modes. We took a 100s scan of the new OMC and without sidebands on, and we zoomed in on the C02 mode peak to examine the astigmatic peak separation, but we found none, as shown in image 3.
The first image is the entire scan, and we are curious to know if the astigmatic separation is much larger than before, leading to a MUCH smaller second peak that our fitting function skips over. The OMCscan fit with nonlinear corrections can be found here
How we did the scan:
- We did 2 100s scan, sweeping H1:OMC-PZT_EXC and reading H1:OMC-DCPD_SUM_OUT_DQ
- We added a Dark offset of .0034 mA to DCPD
- the scan template required that we set the PZT2 offset to - 50
After talking to Keita, he said it is perfectly possible the HOM between between 02/20 is different to the previous OMC and so there might be a very small peak for one that is hidden in the much larger peak. The next step would be to remove the taller peak from the spectrum using the fitted parameters and see what peak is left there.
I checked dcc document LIGO-T1500060. According to this alog, we have OMC #1 now. The new TMS we have between the horizontal and vertical modes should be 0.1092 MHz taken from the vertical and horizotnal TMS in table 19 of LIGO-T1500060. The previous OMC installed was #3 which had a vertical/horizontal mode spacing of 0.2942 MHz taken from table 25.