Reports 1-1 of 1 Clear search Modify search
AdV-DET (Commissioning)
bonnand, gouaty, mantovani, casanueva - 0:37 Tuesday 11 December 2018 (43981) Print this report
Alignment investigations on SWEB, SNEB, SPRB

This morning (Dec 10th) we investigated the impact of the angular setpoints of the suspended benches (SNEB, SWEB, SPRB) on the sensitivity.

We started by recentering the B7 and B8 beams on the SNEB/SWEB camera by adjusting the bench setpoints.

The SWEB angular setpoints were adjusted between 09h10 and 09h15 utc. Initially the SWEB setpoints were TX = +100 urad, TY = 1795 urad. After the recentering on the camera the new setpoints are TX = +90 urad, TY = +1810 urad.

The SNEB angular setpoints were adjusted between 09h18 and 09h21 utc. Initially the SNEB setpoints were TX = -695 urad, TY = -75 urad. After the recentering on the camera the new setpoints are TX = -673 urad, TY = -75 urad.

We tested various angular positions of SWEB around its new setpoints. For each tested position, we took some data with a low frequency line (0.1 Hz) injected at the level of the suspension top stage to move the bench along the Z degree of freedom in order to be able to evaluate the scattered light coupling factor (data will be analyzed off-line). All measurements were performed with the bench tracking loop ON, unless otherwise specified:

1/ SWEB TY scan:

  • SWEB TY = 1815 urad (+5 urad) reached at 09h28m20

09h33m54 Started line injection with amp=50

09h35m05 Started line injection with amp=100 (bench moving by ~+/-20 um)

09h37m36 Line switched off

  • SWEB TY = 1820 urad (+10 urad) reached at 09h38m25

09h39m29 Started line injection with amp = 100          

09h41m30 Line switched off

  • SWEB TY = 1810 urad (0 urad) reached at 09h42m25

09h43m49 Started line injection with amp = 100

09h45m53 Line switched off

  • SWEB TY = 1805 urad (-5 urad) reached at 09h46m30

09h48m18 Started line injection with amp = 100

09h50m40 Line switched off

  • SWEB TY = 1800 urad (-10 urad) reached at 09h51m05

09h52m19 Started line injection with amp = 100           Warning : glitch in the data. Situation back to normal at 09h53m48

09h55m39 Line switched off

  • SWEB TY = 1795 urad (-15 urad) reached at 09h56m10

09h58m14 Started line injection with amp = 100

10h00m37 Line switched off

  • SWEB TY = 1810 urad (0 urad) reached at 10h02m15
  • SWEB TY = 1805 urad (-5 urad) reached at 10h04m05
  • SWEB TY = 1810 urad (0 urad) reached at 10h06m10

2/ SWEB TX scan:

  • SWEB TX = 95 urad (+5 urad) reached at 10h07m25

10h08m42 Started line injection with amp = 100

10h10m43 Line switched off

  • SWEB TX = 100 urad (+10 urad) reached at 10h11m15

10h12m37 Started line injection with amp = 100

10h14m41 Line switched off

  • SWEB TX = 105 urad (+15 urad) reached at 10h15m35

10h16m47 Started line injection with amp = 100

10h18m49 Line switched off

  • SWEB TX = 90 urad (0) reached at 10h19m25
  • SWEB TX = 85 urad (-5 urad) reached at 10h21m20

10h23m23 Started line injection with amp = 100

10h25m45 Line switched off

  • SWEB TX = 80 urad (-10 urad) reaced at 10h26m10

10h27m18 Started line injection with amp = 100

10h30m19 Line switched off

  • SWEB TX = 75 urad (-15 urad) reached at 10h31m00

10h32m44 Started line injection with amp = 100

10h35m39 Line switched off

  • SWEB TX = 80 urad (-10 urad) reached at 10h36m00
  • SWEB TX = 90 urad (0 urad) reached at 10h38m40

10h40m09 Started line injection with amp = 100

Opening tracking loop at 10h42m18

10h44m29 Line switched off

Closing tracking loop at 10h46m48

We tested various angular positions of the SPRB bench. Its initial setpoints were TX = 170, TY = -600 urad:

  • SPRB TY = -595 (-5 urad) reached at 10h55m30
  • ITF unlocked at 11h01m40 (fast unlock)
  • ITF relocked in low noise 3 at 12h30 utc
  • SPRB TX = 170, TY = -595 at 12h44m00
  • SPRB TX = 170, TY = -590 at 12h45m30
  • SPRB TX = 165, TY = -590 at 12h49m00
  • SPRB TX = 160, TY = -590 at 12h51m00
  • SPRB TX = 175, TY = -590 at 12h53m10
  • SPRB TX = 180, TY = -590 at 12h55m00
  • ITF unlocked at 12h56m11
  • SPRB setpoints put back at TX = +170, TY = -595.

At first look it seems that the position TY=-590, TX=165 was a bit better then other positions, to be confirmed after deeper analysis.

Comments to this report:
mantovani - 9:54 Tuesday 11 December 2018 (43982) Print this report

The effect of the angular position of the SWEB bench has been roughly analized (using the high sea activity) by measuring the noise on DARM at each angular position (supposing that the noise is not changing during the sweep).

It is visible that the effect of the bench alignment on DARM is really strong, see Figure 1.

The DARM asd value at 19Hz can be plotted as a function of the bench position and it is visible in Figure 2 and 3 that the best position for ty is ~-7urad while for tx is ~-5urad.

This analisys wll be repeated analizing the coupling factor of the diffused ligth thanks to the z injections.

Images attached to this comment
Search Help
×

Warning

×