Yesterday, Dripta set the XY comparison correction factors to 1.0 for both the Xend and Yend Pcals.
Last night we had a good 10-hour lock stretch during which we can assess the X/Y comparison factor, chi_XY.
The attached plot shows that it is about 1.0025.
Rick Savage, Dripta
We finally assessed chi_XY over a ~ 9-hour lock stretch using a DTT template made by Rick. We set start and end frequency to 410.1Hz and 410.4Hz respectively, BW = 0.001 Hz, Overlap = 50%, and Average=10. For the start times listed below the deviation of Pcal X/Y comparison factor, chi_XY, from 1.0 was calculated by hand:
start time = 05/02/2023, 00:30 UTC --> 27.5 hundredths of a percent (hop)
start time = 05/02/2023, 01:30 UTC --> 27.5 hop
start time = 05/02/2023, 02:30 UTC --> 28.7 hop
start time = 05/02/2023, 03:30 UTC --> 27.7 hop
start time = 05/02/2023, 04:30 UTC --> 25.7 hop
start time = 05/02/2023, 05:30 UTC --> 20.3 hop
start time = 05/02/2023, 06:30 UTC --> 28.1 hop
start time = 05/02/2023, 07:30 UTC --> 30.1 hop
The mean and the standard deviation of the above values are 26.95 hop and 2.77 hop respectively.
Using this new value of chi_XY = 1.0027, we calculated the new correction factors at the X and Y-end, C_X = 1.0012 and C_Y = 1.0015. The EPICS variables for the following channels were updated accordingly,
H1:CAL-PCALX_XY_COMPARE_CORR_FACT : 0.9988 (1/C_X)
H1:CAL-PCALX_XY_COMPARE_CORR_FACT : 1.0015
These changes have been accepted in SDF.