DriptaB, RickS

Following up on setting the Pcal XY comparison factor at 1.0027 (see LHO aLog 69240), we look at 12 hours from the long lock stretch last night: 07:00:00 UTC to 17:00:00 on 5/3/2023.  The attached plot shows the BNS range and output of the Pcal XY comparison channel in minute trends during this interval.

Using DTT as described in LHO aLog 69240, we can calculate the XY comparison factor.  The results are:

start time = 05/03/2023, 07:00 UTC  --> 3 hop (1.0003, or three hundredths of a percent (hop) above  unity)
start time = 05/03/2023, 08:00 UTC  --> 5 hop
start time = 05/03/2023, 09:00 UTC  --> 11 hop
start time = 05/03/2023, 10:00 UTC  --> 10 hop
start time = 05/03/2023, 11:00 UTC  --> 12 hop
start time = 05/03/2023, 12:00 UTC  --> 7 hop
start time = 05/03/2023, 13:00 UTC  --> 14 hop
start time = 05/03/2023, 14:00 UTC  --> 9 hop
start time = 05/03/2023, 15:00 UTC  --> 3 hop
start time = 05/03/2023, 16:00 UTC  --> 2 hop
start time = 05/03/2023, 17:00 UTC  --> 5 hop

The mean of the calculated coefficients is 7.4 hop with a standard deviation of 4 hop.

This seems to indicate that the chi_XY factor is closer to 1.0034 (27 hop already in the correction factors plus the residudual 7 hop measured during this lock stretch.

Though this seems to be an offset between the way we calculate this using DTT and how we are calculating it in the front-end code.  As the lower trace in the attached plot shows, the calculated factor is now clearly varying about 1.0, where the values calculated using DTT are offset by about 1.0007 (7 hop).