VIRGO commissioning progress Paolo La Penna for the VIRGO collaboration European Gravitational Observatory N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 1 Status in December 2005 Virgo shutdown had started after C7 (19 September 2005) The new IB had been installed in the IB tower (end November 2005 The fake dihedron was still mounted on the bench The Nd:YAG beam (up to 5 W for the moment) had been sent into the bench: some light (with even some interference) was visible at the end of the MC The optics on the bench were being realigned using the IB actuators: this operation was performed staying inside the tower, with the laminar flux on and the LC closed The alignment of the IMC was going on (http://www.ego-gw.it/ILIAS-GW/WP1docs/lapenna_121205.ppt) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 2 Since then: The IMC was fully aligned in vacuum at about mid December. IMC locked at end of 2005. Beam at the end of the ITF at begin of January 2006. ITF alignment at mid of January. First ITF cavities lockings at end of January. Full RFC alignment at end of February. Full locking of the ITF going on now (mid of March). The full restart of the ITF, after IB installation, took about three months N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 3 I – Injection system restart N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 4 Operation performed on the Injection System Alignment and locking of the IMC in vacuum Alignment of the IB optics in vacuum Alignment of the beam on the ITF and telescopes tuning Alignment and locking of the RFC Setup and alignment of the EIB BMS IMC matching improvement IMC automatic alignment Power stabilization RFC automatic alignment N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 5 Changes in Virgo after September shutdown PR mirror IB+RFC EIB N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 6 Injection system Lower stage Upper stage N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 7 Difference old-new IB Old IB N5-WP1 8TH MEETING, Frascati, 20/03/2006 New IB Virgo Commissioning Status Paolo La Penna 8 IMC alignment: december 2005 HeNe autocollimation on the MC mirror Acting on the IB alignment (checked with a ccd) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 9 IMC alignment: december 2005 laser YAG beam direct beam centering on the MC mirror acting on the external steering mirrors N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 10 IMC alignment: december 2005 laser MC mirror alignment until IMC resonances are visible N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 11 IMC locking: december 2005 laser Pout 8 W IMC locking Feedback on laser pzt using the reflection as a trigger N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 12 ITF alignment: 13 january 2006 N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 13 RFC alignment and locking: february 2006 The Reference Cavity alignment has taken more time than expected A first attempt to align it using the 20 W beam failed A second attempt after having aligned a probe beam coming from the opposite direction, and looking at the RFC transmission, led to a poor RFC alignment (but it allowed to lock and start working on the ITF) A third attempt overlapping the probe beam and the 20 W beam was successful From the beginning to the end almost one month was necessary N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 14 YAG from inverse path: fringes Probe beam from the inverse path Probe beam superposed to a HeNe passing through the RFC in the lower part Camera looking at the coils frame (hit by the RFC transmission): mode flashing visible ccd Secondary YAG beam 1 V @ 25 Hz pzt scanning N5-WP1 8TH MEETING, Frascati, 20/03/2006 CCD and PhD looking at RFC reflection Virgo Commissioning Status ccd photodiode Paolo La Penna 15 Contrast improvement and alignment YAG probe Reflected beam Contrast = 0.7 N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 16 RFC alignment using PR alignment N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 17 RFC alignment using PR alignment N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 18 Near Field of M13 and Far Field 1m-f FF Screens N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna NF 19 M14 movement 1m-f FF Move M14 and observe overlapping with NF ccd N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status NF Paolo La Penna 20 M13 movement 1m-f FF Correct with M13 to overlap on the FF ccd Move M14 and observe overlapping with NF ccd N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status NF Paolo La Penna 21 After alignment: the 20 W beam resonates in the RFC ccd PhD N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 22 The RFC transmission is not visible with the RFC aligned Inverse path beam and direct beam are being superposed below acting on M13 and M4 mirrors When superimposed both beams should resonate ccd PhD N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 23 RFC locked, reflected 20 W YAG beam: 1 March 2006 Contrast = 54 % (it was 80% before the shutdown) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Good alignment + longitudinal mismatching Virgo Commissioning Status Paolo La Penna 24 RFC alignment: conclusion The RFC alignment was more difficult than expected: the cavity axis was not where it was expected, maybe the RFC was not aligned inside its tank, or it had moved slightly during new IB assembling The RFC is locked in a stable way, with the beam transmitted by the IMC: more stable with the alignment with respect to the previous setup We cannot see the RFC transmission N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 25 Further activities on RFC RFC locking filter change: a new filter has been implemented, which allows a reduction of the frequency noise of the prestabilized beam RFC automatic alignment: this activity is going on; it will allow to keep the beam aligned on the RFC using the two closed loop pzt placed before the RFC. This allows shifts of the beam on the upper part, in order to better align the upper part optics, without losing the RFC alignment N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 26 Problems encountered Several problems/failure have occurred: it has been necessary to open the IB tower twice DPS misaligned Wrong PSD electronics TS damaged Beam clipped PM stuck RFC_trans clipped N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 27 Further activities involving the injection system After the restart of the IB, some new features and other activities have been performed: Beam Steering System IMC matching improvement IMC automatic alignment restarted Input power stabilization (the photodiode measuring the IMC transmission has been changed) RFC automatic alignment PSD on the IB working (new homemade electronics) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 28 BMS: DC quadrants, ABP actuation BMS allows to keep beam aligned with respect to DC_quadrants placed on the External Injection Bench. The signal from the DC quadrants is sent to the ABP (Automatic Beam Positioning) mirrors (pzt steered mirrors). It allows a stable and repetitive positioning of the beam entering into the IMC; It allows performing pure translations and angle of the beam. ABPs NF QF FF QF (on laser bench) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 29 IMC matching With the help of BMS, IMC matching has been improved: 96% matching (it was 82%), 91% contrast (should correspond to about 1500 ppm losses in the IMC). IMC transmission is now about 8 W (at about the same level as before the shutdown) This power is entering into the ITF (we had 0.7 W entering into the ITF before the shutdown) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 30 IMC automatic alignment The AA of the MC is working again as before the shutdown (for the moment acting only on the MC mirror, correcting the FF_vert and the NF_horiz degrees of freedom. The (new) AA of the IB is ready to be implemented: it should replace the LC of the IB N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 31 Power Stabilization IMC_trans HF Master laser Diode current Data from spectrum analyser is 50 times lower in the 100Hz region than dataDisplay measurent (above) (to be investigated) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 32 RFC automatic alignment M15 RFC AA now separated from IMC AA M16 Wavefront sensing quadrants on the EIB Closed on the vertical DOF (1 Hz bandwidth) Horizontal DOF not working (M16_PZT horiz. not working properly) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 33 New PR mirror: monolithic and higher R (0.95 vs 0.925) Comparison between the old (black) and new monolithic (red) PR mirror N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 34 II- ITF restart N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 35 IB LC after RFC locking The IB LC filters were changed after restart: frequency noise was reintroduced N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 36 Frequency noise after RFC locking (ITF misaligned) IB transfer function Frequency noise N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 37 IB LC filter upgrade IB in high noise control IB in low noise control Blue curves: MC in high/low noise (factor 100 G difference) Red curves: MC in high/low noise (factor 100 G difference) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 38 MC-RFC locking filter: after restart Too small G SSFS couldn’t engage N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 39 Frequency noise after RFC locking (ITF misaligned) Purple: C7 Black: after new IB RFC locking N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 40 New MC-RFC locking filter upgrade N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 41 New frequency noise: SSFS can engage N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 42 Frequency noise: C7 (beam attenuated) vs now Now C7 N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 43 ITF restart: locking Since end of January: Photodiodes gains readjusted for the higher power (10 times more than before shutdown) Automatic alignment restarted: Tested the drift control of the two cavities Quadrant photodiodes gains adjusted Not gone further because it needs the full locking of the ITF PR-NI PR-NE CITF NE-WE-BS NA WA Recombined SSFS Variable Finesse with PR misaligned …. Now the full recycled ITF is being locked N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 44 SSFS B8p B2_3f_ACp PR (PRCL) B1p_DC BS (MICH) B5_ACp SSFS (CARM) B8_ACp NE-WE (DARM) L1 l1 l2 L2 B2_3f_ACp l0 SSFS using CARM for the Beam Frequency stabilization N5-WP1 8TH MEETING, Frascati, 20/03/2006 B5_ACp B1p_DC Virgo Commissioning Status Paolo La Penna 45 SSFS restart The restart of SSFS required some gain tuning because: RFC locking filter was different Frequency noise was different RFC gains are different After tuning readjustment, IB LC filters and RFC locking filter SSFS is now working properly N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 46 Towards the dark fringe B8p STEP 7 B2_3f_ACp PR (PRCL) B1p_DC BS (MICH) B5_ACp SSFS (CARM) B8_ACp NE-WE (DARM) L1 l1 l2 B2_3f_ACp L2 l0 SSFS using CARM B5_ACp B1p_DC N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status DF 0.05 Paolo La Penna 47 ITF locking Here we are Status on 16th March: ITF locked up to step 7 (0.05 of the dark fringe) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 48 Parabolic telescope T2: M6 mirror misalignment 3 closed loop picomotors Tilted: tx (650 mrad) and ty (850 mrad) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 49 Effect of M6 misalignment M6 aligned (beam at 3 km) M6 misaligned (beam at 3 km) (Qx=650 mrad Qy=850 mrad) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 50 Resulting beam shape Beam size at NE: wx= 60mm wy= 60mm Beam size on Cam5: wx= 0.7mm wy= 0.42mm To fit these measurements, the beam parameters inside ITF with respect to BS position are (perfect matching for w=21.3, z=0): wx= 15mm, zx= -400m wy= 23mm, zy= 800m The matching on the FP cavities should be around 89% in these conditions: confirmed by measurement (88%). Beam parameters before shutdown: wx= 18mm, zx= -500m wy= 18mm, zy= 500m) N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 51 Short telescope T1 centering DY L1 L2 f=130 f=-80 D=60mm ccd N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 52 Beam shape after the Faraday isolator Dy=2 mm Dw/w = 2% N5-WP1 8TH MEETING, Frascati, 20/03/2006 Dy=4 mm Virgo Commissioning Status Dw/w = 9% Paolo La Penna 53 Conclusion The restart of the Injection System has required more than two months The new Injection System is now working The ITF is close to final locking with full power (8 W) Some problems involving the new IB remain open: The RFC matching is poor and the RFC transmission is not sent out of the IB tower The astigmatism of the beam has to be corrected For the moment the effort is in achieve the full locking again and, since we can go on in these conditions, to pospone the solving of this problems to a later moment N5-WP1 8TH MEETING, Frascati, 20/03/2006 Virgo Commissioning Status Paolo La Penna 54