Status and perspectives of the Virgo detector

Transcription

1 Status and perspectives of the Virgo detector Viviana Fafone Università di Roma Tor Vergata and INFN On behalf of the Virgo collaboration TAUP 2009, 1-5 July 2009 V. Fafone Status and perspectives of the Virgo Detector TAUP

2 Steps from Virgo to Virgo+ May '07 - Sep '07 First Virgo Science Run (VSR1) Oct '07 - May '08 Commissioning Scattered light mitigation: replaced brewster window by cryotrap TCS installation, mirror magnets strength reduction 9 May '08 Vacuum viewport failure May - Oct '08 Virgo+ shutdown Injection system, infrastructure and electronics upgrade NE payload recovery, replacement of all viewports Oct '08 - now Commissioning Remaining electronics upgrade Commissioning with more input power and TCS Noise hunting 7 Jul '09 Start Second Virgo Science Run (VSR2) 2010 Monolithic suspension upgrade? V. Fafone Status and perspectives of the Virgo Detector TAUP

3 Incident recovery Caused by weak design of view-port, identified and tested safer model Replaced about 90 view-ports throughout whole interferometer Cleaned and tested North-End tower New payload at North-End: coating of already polished spare mirror V. Fafone Status and perspectives of the Virgo Detector TAUP

4 Interferometer restart Interferometer no longer showed bi-stability during lock acquisition Different working point: modulation frequency changed by 700 Hz Maybe caused by slightly different radius of curvature of new mirror V. Fafone Status and perspectives of the Virgo Detector TAUP

5 Virgo+ upgrade: electronics New ADCs: from 16 to 18 bit New quadrants read-out electronics for alignment Virgo+ upgrade: infrastructure Replaced complete wiring of main power and grounding in central building Replaced and doubled UPS Replaced 15 kv transformer New hot water pipes Lowered speed of airconditioning V. Fafone Status and perspectives of the Virgo Detector TAUP

6 Virgo+ upgrade: injection system New laser amplifier: up to 60 W (25 W at interferometer input) New pre-mode-cleaner Remotely tunable in-vacuum Faraday Isolator Heavier input-mode-cleaner end-mirror V. Fafone Status and perspectives of the Virgo Detector TAUP

7 Thermal Compensation System Absorption of a small fraction of the laser beam (few ppm of 10kW) inside the Virgo mirrors => lensing effects => aberration of the beam, bad error signals Essential for compensating thermal lensing in input mirrors when working with high input powers Annulus and central spot from CO2 laser on both input mirrors. They can be operated independently. Not yet stabilized in amplitude, some evidence for introduced noise V. Fafone Status and perspectives of the Virgo Detector TAUP

8 Phase camera Field amplitude Phase of field components wrt a reference field (without aberration) Beam scanned on pinhole detector, signal demodulated to separate carrier and sidebands Located on dark fringe before output-mode-cleaner (B1p) Extensively used, but more as 'amplitude camera' TCS fine alignment, 'cold interferometer' experiments Characterization of thermal effects V. Fafone Status and perspectives of the Virgo Detector TAUP

9 High power operation Power increased in steps from 8 W (VSR1) to 17 W now limited by mismatching of reference cavity due to thermal effects No major problems with interferometer stability Some alignments loops more critical Currently about 1.5 W on both mirrors: interferometer similar to 8W 'Cold interferometer' with about 2x 6W More optical gain, ideal frequency stabilization TF, but TCS too noisy without TCS with TCS V. Fafone Status and perspectives of the Virgo Detector TAUP

10 Noise budget Low frequency Some environmental Some scattering Laser bench resonances Actuator noise Medium frequency Coating thermal noise Detection bench resonances TCS noise? High frequency Noise budget is well understood Shot noise V. Fafone Status and perspectives of the Virgo Detector TAUP

11 Sensitivity May 2007: ~3 Mpc May 2009: ~8 Mpc V. Fafone Status and perspectives of the Virgo Detector TAUP

12 Future work During the run (commissioning breaks) TCS power stabilization? More noise hunting Stabilization of 'etalon effect' Long term Monolithically suspended mirrors, finesse 50 -> 150 V. Fafone Status and perspectives of the Virgo Detector TAUP

13 Whereweare (13 15 Feb 2009) Present limits: In the Hz range the main noise source is the thermal noise expected for the Virgo Herasil end mirrors We need to change the mirrors if we want to profit from the larger injected power. V. Fafone Status and perspectives of the Virgo Detector TAUP

14 New mirrors and coatings New Suprasil end and input mirrors The loss angle expected for this material is about 10-9, a new perspective is open in the middle frequency range; Further improvement with higher finesse: F=150 instead of the current 50. New coatings (TiO2 dopants: lower mechanical dissipation) New cleanliness procedures Use of a special protecting film; Virgo, 50W, F=150 BNS: 24.7 Mpc BBH: 126 Mpc V. Fafone Status and perspectives of the Virgo Detector TAUP

15 Monolithic suspensions Virgo+ with monolithic suspension Thanks to the lower mechanical dissipation of the fused silica, a monolithic suspension promises an excellent performance by reducing all the losses Virgo+ average sight BNS: 53.6 Mpc BBH: 284 Mpc V. Fafone Status and perspectives of the Virgo Detector TAUP

16 Monolithic suspensions (2) The assembly Steel box to host the upper silica clamp on the marionetta Coupling to the mirror flats with New Ears Silica Clamps on the marionette Silicate bonding Silica anchors Silica ears bonded to the mirror flats V. Fafone Status and perspectives of the Virgo Detector TAUP

17 Monolithic suspensions (3) Silica wires: fiber production Fiber production validated Implemented the fiber welding with the laser on the lower and upper silica clamps; V. Fafone Status and perspectives of the Virgo Detector TAUP

18 Monolithic suspensions (4) The payload Marionette (110 kg): amagnetic steel AISI 316L, dielectric arms (peek) no eddy current and magnetization effects; designed to be fully compatible with the monolithic suspensions assembly; equipped with mirror for LC purposes; step motor to displace a balancing weight; Recoil Mass (60 kg): amagnetic steel AISI 316L outer cylindric mass (500 mm diam); dielectric inner ring (peek CF30) no stray currents or magnetization effects it carries four coils for e.m. actuation on magnets attached on the mirror rear side; suspended with steel C85 wires (0.6 mm diam.) option: it can carry the markers for the LC purposes equipped with safety stop (peek made) Mirror (21 kg): FS with lateral flats (350 mm diam), silica ears attached with silicate bonding suspended with silica wires (285 μm diam) magnets attached on rear side option: markers attached on front side (LC) V. Fafone Status and perspectives of the Virgo Detector TAUP

19 Concluding Robust interferometer 81 hour lock during Easter WSR13/E14 (June 12 th -15 th, 2009): 95% duty cycle Stable horizon: Mpc fluctuating with input mirror etalon effect Low glitch rate: factor 10 lower than VSR1 Ready to start VSR2 Preparing for installation of monolithic suspensions V. Fafone Status and perspectives of the Virgo Detector TAUP