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Paolo La Penna ILIAS N5-WP1 meeting Commissioning Progress Hannover, July 2004 C4 sensitivity
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Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
VIRGO commissioning progress report
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Status in C4
Recombined locked (full Virgo with PR misaligned)
Arms automatic alignment
Top stage tidal hierarchical control
Second stage of frequency stabilization (laser frequency controlled with the ITF common mode)
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
C4 sensitivity
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
After C4: hardware operation
Installation of new terminal benches support: terminal photodiode movements solved, possibility to perform DC drifts control
Rearrange optics on terminal benches: spherical aberrations solved, Gouy phase and telescope tuning for AA possible
MC mirror cleaning & check: attempt to reduce the scattering inside the Mode Cleaner, with no result (scattering still there)
….
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
After C4: action performed
IB drift from the NE quadrants DC: not finished BS drift control from the WE quadrants DC: complete BS automatic alignment (as on the WI mirror): not yet finished Low noise coil drivers (switch from high power for lock acquisition
to low noise for lock keeping): complete Compact DSP cards to overcome DSP memory limits: complete IB local control acting from the marionette: complete ‘New’ cavities automatic alignment: complete Cavity full hierarchical control via marionette: not yet finished M6 replacement (beam attenuation to 10%) to reduce the
feedback from the PR in the IMC: complete
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
After C4: main control upgrades summary
NE filter 7 control: chain resonance (16 mHz) and filter 7 movement damping
IB control from the marionette: reduction of resonances in the IB control (introduced through the bench coils)
New coil drivers: reduction of DAC noise on the RM coils
Beam splitter automatic alignment: BS drift control and AC AA on the BS as on the WI mirror
Marionette control started (demonstrated successfully on a single arm) but need AA and SSFS to go on
Recycling locking started (stable lock of state 3) but need AA and new M6 to go on (PR feedback inside the IMC makes the system unstable)
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Filter 7 control
LVDT used as sensor and actuator (in different frequency ranges) to damp the Filter 7 motion;
Damp the 16 mHz motion (chain mode), active up
to 100 mHz;
Used only for damping
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Chain resonance damping from Filter 7
ONOFF
OFF
32 mHz
16 mHz32 mHz
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
IB marionette control
In C4 the Injection Bench was controlled locally through the IB bench coils;
Many resonances (bench, wires, Reference Cavity, …) where detected in the ITF signal;
A new control of the IB through the marionette has reduced or made disappear many of these peaks.
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
IB marionette control
IB coils control
Marionette control
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
New low noise coil drivers
10-1
100
101
102
103
10-20
10-15
10-10
10-5
Actuators noise: current status
Frequency (Hz)
m/H
z1/2
Reference Mass - Mirror Actuators NoiseFilter #7 - Marionetta Actuators NoiseVIRGO Sentivity
DAC noise: 300 nV/sqrt(Hz) (17.5 effective bits) Coil Driver noise: 80 nV/sqrt(Hz)
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
New low noise coil drivers
The required additional force for lock acquisition is provided by a transconductive amplifier.
During lock acquisition phase only DAC 1 is used.
During linear phase DAC 1 output set to zero and DAC 2 is used to keep the lock.
LCoil3mH
1
2
RCoil10
Ref. Mass Coil
+
-
OUT
R2
R
R1R
Coil DriverDAC 2
RN
500
DAC 1Transconductance Amplifier
1
2
Relay
+
-
OUT
R1
R
R2
R
C11 2
De-emphasys Filter
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
BS control
AC control of the AA added to the BS: local controls switched off;
DC BS drift using the West End quadrants on;
Never tested AC and drift correction together;
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Cavity marionette control
Full hierarchical control of a cavity closed: RM+Marionette+IP tidal control
Yet without AA and Second Stage of Frequency Stabilization
Tested soon the full hierarchical control with AA and SSFS
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
North cavity full hierarchical control
No change in the cavity power when control starts
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
North cavity full hierarchical control
RMS reduction by a factor 3 at low frequency
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Recycling locking: state 3
• Lock of the central cavity (CITF) on the sidebands + lock of the north arm (on the carrier) achieved
B2_ P B1_ Q
B2_ Q
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Virgo in state 3: effect of the PR alignment in the IMC
When the PR is aligned fringes in the power inside the IMC appears: frequency noise, prenvents locking
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Beam attenuation: M6 replacement
The light reflected in the IMC is partially scattered by the MC in the Virgo beam direction, creating spurious fringes;
The fringes in the IMC make frequency noise,which prevents the PR locking;
To temporary solve the problem of the PR feedback in the IMC it has been decided to attenuate the beam entering in the ITF by a factor 10 (factor 100 attenuation of fringes in the IMC;
To do this the last mirror injecting the beam in the ITF has been replaced with a 10% reflective mirror.
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
M6 replaced with a 10% reflecting
From the laser
To the interferometer
M6 IMC
Reference Cavity
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
After M6 replacement
Virgo is now working with 10% of the C4 power (about 0.7 W on the PR instead of the former 7 W);
Electronics and controls scaled to 10% power;
Recombined realigned and locked;
Arms automatic alignment restarted;
Fringes in the IMC when the ITF and the PR are aligned are strongly reduced;
Tests for full Virgo locking have started.
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Future upgrade: new Injection Bench?
The PR reflection inside the IMC are a problem: the MC scattering in the IMC axis direction creates instabilities;
An isolation is necessary: on the present Injection Bench there is no space for a Faraday Isolator;
A new Injection Bench will be probably made: its main difference will be the presence of a Faraday Isolator;
The expected installation should take place in the begin of next year. In the meanwhile Virgo will work with 10% of its power.
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
New Injection Bench
900 mm
Faraday Isolator
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Progress in sensitivity
10 100 1000 1000010-2010-1910-1810-1710-1610-1510-1410-1310-1210-1110-1010-910-8
C1 (North Arm) C2 (North Arm) C3 (North Arm) C3 (recombined) C4 (recombined) Design
m/s
qrt(H
z)
Hz
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Changes with respect to C4
Sensitivity measured before replacing M6 with the 10 % reflecting mirror (7 September 2004):
Low noise RM coils drivers;No BS control at the level of the RM (no drift;
correction, no marionetta notches compensation);BS drift control (WE quadrants DC through BS
marionette);IB marionette control;Input mirrors coils disconnected
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
7 September data taking
BS control upgrade
Frequency stab.problems (?)
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Next steps
In the next month the activity will be directed to the locking of the full Virgo;
The PR locking test have already started;
In the 10-100 Hz the noise is dominated by frequency or angular jitter noise coming from the Injection system: coupling with acoustic noise? IB internal resonances? This problem is being investigated.
Paolo La PennaILIAS N5-WP1 meetingCommissioning Progress
Hannover, 23-34 July 2004
Next run planned conditions
PR locking Arms marionette control Better BS control New coils drivers Full Automatic Alignment … When? (in one month from now?)