Reports until 13:16, Monday 15 August 2016
H1 CAL (CAL)
sudarshan.karki@LIGO.ORG - posted 13:16, Monday 15 August 2016 - last comment - 16:21, Monday 15 August 2016(29104)
Calibration EPICS Value
Comparison of Calibration Epics Values (Calibration parameters at t = t0) during O1 and ER9.

Param.        Description           2015/09/29         2016/08/03             2016/08/10 
---------------------------------------------------------------------------------------------------------
EP1           ~1/Atst0 (ftst)              2.2005e+16        2.1066e+16          4.9121e+17         

EP2          ~Delta C/(1+G)        0.9895                 0.9934                  0.9934         
EP3          1/Apu0 (fctrl)               2.1115e+16         2.1077e+16           2.1077e+16         

EP4          Atst0 (fctrl)                  5.4972e-17          5.6354e-17            5.6354e-17    
 
EP5          Apu0 (fctrl)                  4.7360e-17          4.7446e-17            4.7446e-17            

EP6          Cres(fpcal2)                1.1307e+06          8.9859e+05           8.9859e+05
EP7          D0(fpcal2)                  1.7599e+07          1.5871e+11           1.5871e+11    
 
EP8          Atst0 (fpcal2)               1.2178e-18           1.13718e-18          1.13718e-18          

EP9          Apu0 (fpcal2)               2.0898e-19           2.0235e-19            2.0235e-19
 
The numbers in the first column are from O1. The numbers in second and third column are  ER9  values. All values in column 2 and column 3 are same except EP1. There was dicrepancy in this value because we changed the way the tst line was  injected during ER9 (compared to O1) and didnot account properly for the change. However, EP6 and EP7 values changed significatly between O1 and ER9. Change in EP6  accounts for the change in optical gain and is real. However 4 order of magnitude change in EP7 looks fishy. 
Comments related to this report
darkhan.tuyenbayev@LIGO.ORG - 16:21, Monday 15 August 2016 (29108)CAL

Evan H., Darkhan T.,

Details

  • A calibration line for calculating the time-dependence of ESD actuation strength during ER9 was injected from SUS-ETMY_LKIN_P (see LHO alog 28164). Later we found that the amplitude of this line in the DARM spectrum recorded during ER9) was unsufficient for tracking the ESD actuation strength. So, the EPICS values for time-dependendent factors were recalculated on Aug 10 for using a calibration line injected from SUS-ETMY_L3_CAL_LINE.

The transfer function for the SUS-ETMY_L3_CAL_LINE line includes DRIVE_ALIGN filter, which is not the case for a line injected from SUS-ETMY_LKIN_P. The gain of this filter at cal. line frequency is ~22, this explains EP1 value change.

  • As Sudarshan pointed in the original alog, the optical gain measured prior to ER9 was ~20% lower compared to O1 (explains change in EP6).
  • One of the explanations for a several-order-of-magnitude change in EP7 (D0 at 331.9 Hz), could be that during ER9 we, by mistake, did not turn on the notch at 331.9 Hz. In O1 run this notch was in LSC-DARM, FM7 (see LHO alog 20075). After adding a second set of filter modules (now LSC-DARM1 and LSC-DARM2) the notch was moved to LSC-DARM2, FM4, but was not turned on during ER9.

Note: LSC-DARM2, FM4 will be turned on during nominal low-noise operation in ER10/O2 (must not forget to include this into Matlab DARM model).