1 Virgo commissioning: Next steps December 12 st 2005 Hannover, ILIAS-GWA WG1 Matteo Barsuglia, LAL/CNRS

2 C6 (July 29th – Aug 12th) – Input power ~ 0.8 W – Partial automatic alignment – Science mode duty cycle 86% – Longest lock 40 hours – Best range for optimally oriented inspirals 0.5 Mpc – Automatic science mode recovering ~5 minutes C7 (Sept 14th - Sept 19th) –Input power ~ 0.8 W –10 d.o.f. automatic alignment and full hierarchical control –Science mode duty cycle 65% –Longest lock 14 hours –Best range for optimally oriented inspirals 1.65 Mpc –Automatic science mode recovering ~5 minutes C6 and C7 summary

3 Noise budget run C7 Shot noise Control noises

4 Short term milestones New injection bench commissioning and mode-cleaner restart Goal: Have a stable ~10 W beam transmitted by the input mode-cleaner ~ end of the year  See Paolo’s presentation Interferometer restart Goal: Measure a new sensitivity curve with high power interferometer ~ end of January

5 “Interferometer restart” milestones Full interferometer lock Differential mode automatic alignment Hierarchical control and low noise coil drivers Calibration and sensitivity curve measurement Beam alignment and beam matching  see Julien’s presentation North and west cavities lock and automatic alignment New PR transfer function and central area interferometer lock Full interferometer lock

6 Full lock - concerns Problems not fully understood or solved: frequency stabilization (SSFS) oscillations during lock acquisition (Seems to be connected with interferometer alignment) Offsets in the reflected signals Bistabilities (“jumps”) Problems related with the power increase: Stray light on the beam splitter Thermal effects ? (negligible from simulations) Problems related with new power recyling reflectivity (0.92  0.95) Not a problem from analytical computations

7 Linear alignment

8 Linear alignment milestones Differential mode (2 dof) 10 dof as C7 (all the mirrors under linear alignment except WI or BS) 12 dof (all the mirrors under linear alignment) 12 dof and beam control (injection bench controlled through B8 DC)

9 Noise hunting Shot noise at high frequency  increase the incoming power

10 Road-map for 2006 and 2007 Completion of recycled interferometer commissioning ~ 3 months (finish automatic alignment + refinement of other controls) Noise hunting ~ 4 months Science run I ~ starting during fall 2006 Shutdown (if needed) starting early 2007 ~ 2 months Noise hunting Science run II, starting second half of 2007

11 Goal for the first science run factor 10 in the optimally oriented inspiral horizon (1.5 Mpc  15 Mpc)  Priority f > Hz

12 Virgo design –M=0.017 A m 2 –Stainless Steel RM –Q eddy =1.8×10 8 Current design –M=0.05 A m 2 –Aluminum RM –Q eddy =9.4×10 5 Eddy currents problem

13 Noise hunting at high frequency Read-out noise (shot and electronic)  reach 500 W on the beam-splitter x 10 power Increase of recycling factor (R_PR: 0.92  0.95) Better input mode-cleaner matching Decrease losses between laser and mode-cleaner (better optical components on the laser bench)  See Edwige’s presentation Laser noises hunting: Frequency noise (Power increase and optimization of the servo) Oscillator phase noise (Marconi generator changed) Power noise at the modulation frequency (pre-modecleaner if needed) Power noise in the detection band (decrease acoustic couplings)

14 Noise hunting in the central region: actuators Virgo design

15 NE beam Noise hunting in the central region: Diffused light Many beams already dumped on end benches and external injection bench Experience with beam dumpers See Gabriele Vajente’s presentation in Perugia

16 Noise hunting in the central region: acoustic noise Acoustic mitigation in the laser lab on going All the racks with fan moved far from optical tables A coverage of the optical tables will be implemented in spring similar actions to the detection lab if needed

17 Shutdown after first science run Possible plans for the shutdown: Change beam splitter Change the mode-cleaner mirror Further acoustic mitigation Fix Eddy current problem

18 New beam splitter mirror IB WA NI wedge diameter now = 23 cm Increase size, new wedge Maybe increase reflectivity of 2nd face (increase SNR for pick-off signals)

19 New mode-cleaner curved mirror Defects in the MC curved mirror  losses ~ 800 ppm instead ~100 ppm The mirror can be replaced with a better one (and a bigger one?)

20 Second noise hunting phase Decrease also noise in the low frequency region (<50 Hz) and approach the design sensitivity Angular degrees of freedom noise  See Henrich’s presentation Longitudinal degrees of freedom noise Beam splitter noise Power recycling noise

21 Beam splitter noise reduction

22 Summary First sensitivity curve with high power ~ end of january Complete automatic alignment (12 dof + beam control) + refinements of other controls Noise hunting preparation on going (priority f>50 Hz) Science run during fall 2006 (goal 15 Mpc for optimally oriented inspirals) Plans for a shutdown in early 2007 Noise hunting at low frequency Second science run ( goal ~ Virgo design sensitivity)