commissioning

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					Virgo commissioning status
          M.Barsuglia
          LAL Orsay




                             1
               The central interferometer
                       Spring 2001- Summer 2002



          BS




Test of the technical choices during end of the construction
Acquire experience (no prototype in the Virgo community)
                                                               2
          Technical choice validation

• Suspensions
      • direct measurement of the attenuation at 4 Hz
      • hierarchical control (top stage, reference mass)
      • long term operation, robustness…

• Digital controls
      • control of SA resonances, lock acquisition, WFS

• Output mode-cleaner
      • contrast improvement

• Local controls


                                                           3
                  Suspension system

                       Top stage




                               Last stage




Seismic filters
                                            4
Detection system




                   5
OMC locking

                     Transmitted power



    TEM00   TEM00
                    TEM00      TEM00




                             c2 signal


                                     6
        CITF sensitivity during e-runs



Alignment                          Sept
control                            2001




  Frequency noise
                                   July
                                   2002


                                      7
             Lock robustness during e-runs

Run   #losses          duty cycle   longest lock
E0       1               98%           ~   51   h
E1       1               85%           ~   27   h
E2       3               98%           ~   41   h
E3       4               98%           ~   40   h
E4       4               73%           ~   14   h

             ITF stored power
                                           ~ 200 W




                                                     8
July 2002  September 2003: Upgrade to Virgo
• mirrors installation
• arm completion, vacuum
• ITF upgrades (mode-cleaner, local controls, …)

September 2003: Virgo commissioning




                                                   9
               Commissioning plan

• North arm
      • Lock acquisition
      • output mode-cleaner
      • 3-days engineering run
      • frequency stabilization
      • WFS
      • hierarchical control (top stage, marionetta, reference mass)

• West arm
• Recombined ITF
• full ITF
                                                               10
      Interferometer operation: shifts
• 2 8-hours shifts during commissioning


         Morning Shift (8h-15h)                   Evening Shift (16h-23h)
                Task #1                                    Task #2
        1 Interferometer operator                1 Interferometer operator
                            1 Interferometer coordinator
                              1 Computer operator
         1-3 People working on                  1-3 People working on
         commissioning task #1                  commissioning task #2

                              Daily meeting (15h-16h)


• 2 tasks in parallel


                                                                             11
                North cavity locking scheme
                                  • angular control (pitch, yaw)
                                  • no longitudinal damping
       PR
                    BS




~6W

                              50 Hz BW, digital control
                         |Gain|
   1 pole at 0.01 Hz
   2 zeros at 10 Hz
   2 poles at 800 Hz
   1 pole at 1000 Hz
                                                  frequency        Hz
                                                                    12
              Signals and simulation
              Lock acquisition speed threshold ~ 10 mm/s

                       m


                                                      Linearized error
                                                           signal


                                                     No Linearized error
                                                            signal




                Correction           Transmitted P
Time domain
Simulation
(Siesta)

                                                               13
                    locking
                              • Locking at the first
                              trial
Transmitted power             • first lock ~ 1 hour
                              • frequency noise




                                          Frequency noise
                                          reduction


                                                       14
            Lock acquisition statistics
                                      with the linearized error signal

 24 locking events collected locking and delocking the cavity
 23 lock acquisition at the first attempt, only 1 failed locking
attempt




                                                                     15
                 Lock acquisition statistics
 Relative velocity between the mirrors computed for each locking attempt




                                                     2.5 mm/s: mean value
                                                        of the velocity



                                               8 mm/s: maximum velocity for
                      Failed locking
                        attempt               the lock acquisition success

                       v ~ 12.5 μm s


                                               12.5 mm/s: velocity of the
                                              failed event
             8
                                       μm s                                 16
                Output mode-cleaner locking

Transmitted P           c2           Reflected P


                             2 min




  Error signal          State        Temperature




                                                   17
         Output mode-cleaner locking -II




        1. Cavity locked with ~ 1% of the light

            2. Mode-cleaner locked

3. Control transferred to this phd ~ 99% of the light

                      Sensitivity (m/Hz)

                                 Before OMC
                         After OMC




                                                        18
North cavity noise budget


        Control noise ?

                 Frequency
                 noise
                             MC length
                              control
                               noise


                                      Electronic
                                     noise (ADC)



Shot noise




                                              19
                    50 Hz
          Ref Cav




laser

300 kHz


                            50 Hz



                                    20
    Transmitted P during C1 run
        3 days 14-17 november



                                Seismic Noise
                                   problem




tests
                    Lock lost


                                                21
                         300 mHz problem

• large seismic noise during the run @300 mHz
• new inertial control scheme “less inertial”
• roll resonance at 300 mHz excited
• new local controls: transform rollyaw
• solutions  come back to an inertial control and notch at 300 mHz




                                                               22
           Tidals during C1 run

Correction sent to the end test mass




                                       50 mm




                                               23
               Commissioning plan

• North arm
      • Lock acquisition
      • output mode-cleaner
      • 3-days engineering run
      • frequency stabilization
      • WFS
      • hierarchical control

• West arm
• Recombined ITF
• full ITF
                                    24
                    Frequency stabilization



                         50 Hz
          Ref Cav




laser

300 kHz


                                              50 Hz



                                                      25
                    Frequency stabilization
                          3 actions:
                          - unlock reference cavity
                          - change IMC curved mirror locking point
                          - open second stage of frequency stabilization


                         50 Hz
          Ref Cav




laser

300 kHz


                                                            50 Hz
                                             10 kHz

                                                                    26
                      Frequency stabilization


                      DC control of laser frequency allows OMC locking


                                50 Hz                                      1 Hz
            Ref Cav




laser

  300 kHz




                                                    20 kHz.

                                                                          27
           Frequency stabilization: first tests
Cavity trans P    Test mass corr    2nd stage ON   Cavity err sig




                 Cavity corr OFF   2nd stage ON

       • switch
       • oscillations
       • simulink model
                                                               28
       • next try this week
                             WFS control




                                                 matrix


• matrix measured
• transition from local controls  WSF control


                                                          29
                                West arm locking

• started last friday
• first locks ~ few minutes

         • local controls problem  alignment fluctuations




                                      3 min


                                                             30
               Commissioning plan

• North arm
      • lock acquisition
      • output mode-cleaner
      • 3-days engineering run
      • frequency stabilization
      • WFS
      • hierarchical control (top stage, marionetta, reference mass)

• West arm
• Recombined ITF
• full ITF
                                                               31
Hierarchical control: 3 points




                             32
              Hierarchical control: top stage

 Done during the CITF                     Slow corrections (f < 70 mHz)
 commissioning

Force applied to mirror

                    No feedback to top stage
         3.5 mN




             with feedback to top stage
                                                          Fast corrections (f > 70 mHz)


                                                                                33
            Hierarchical control: marionetta

• acquire the lock with the reference mass
• move the control to the marionettaDAC noise reduction
• complicated transfer function  simulations




                                                           34
               Commissioning plan

• North arm
      • Lock acquisition
      • output mode-cleaner
      • 3-days engineering run
      • frequency stabilization
      • WFS
      • hierarchical control

• West arm
• Recombined ITF (january)
• full ITF
                                    35
            Recombined ITF
     B8




            west arm




                       north arm
                                   B7




            B5


B2    B1p

                                        36
     Lock acquisition
       B8

                   Step 1: lock north arm
                   Step 2: lock west and mich




                                            B7




              B5


B2      B1p

                                                 37
                     Recombined ITF: simulation

    north cavity locked   west cavity locked     mic locked




   Acq_north ON            Acq_west_mic ON




Trigger north satisfied   Trigger west&mic satisfied          38
               Commissioning plan

• North arm
      • Locking, output mode-cleaner (done)
      • 3-days engineering run
      • frequency stabilization, WFS (in progress)
      • hierarchical control (top stage, marionetta, reference mass)

• West arm (in progress)
• Recombined ITF (january)
• full ITF



                                                               39
        Lock acquisition for full ITF

• Lock acquisition LIGO scheme
• Time-Domain simulation (Siesta)




                                        40
                          Summary

• North arm
      • Lock acquisition (done)
      • output mode-cleaner (done)
      • 3-days engineering run (done)
      • frequency stabilization (in progress)
      • WFS (in progress)
      • hierarchical control (january)

• West arm (in progress)
• Recombined ITF (january)
• full ITF (?)
• Science (?)
                                                41

				
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posted:8/3/2012
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