Prova

Document Sample
Prova Powered By Docstoc
					VIRGO EXPERIMENT
 VIRGO: a large interferometer for
    Gravitational Wave detection
   started its first scientific run

            F. Frasconi I.N.F.N. Pisa
           for the Virgo Collaboration
     TAUP2007 Sendai , September 11-15, 2007
       The Interferometer at EGO site

        NIKHEF Amsterdam, LAPP Annecy, INFN
        Firenze-Urbino, INFN Genova, IPN Lyon,
       INFN Napoli, OCA Nice, LAL Orsay, ESPCI
         Paris, INFN Perugia, INFN Pisa, INFN
             Roma1, INFN Roma Tor Vergata




September 11, 2007   F. Frasconi / INFN Pisa     2
             VIRGO Optical scheme


           Input Mode Cleaner (145 m)

                                                        3 km long Fabry-Perot
                                                              Cavities

Laser 20 W                       Power
                               Recycling




                                                   Output Mode
                                                  Cleaner (4 cm)


September 11, 2007            F. Frasconi / INFN Pisa                           3
                     Injection System


• Based on a Nd:YVO4 laser source
  with 20 W power (l= 1.064 mm)




                      Laser
                      Cavity




September 11, 2007             F. Frasconi / INFN Pisa   4
               Injection System (cont.)
• Input mode cleaner cavity
  about 145 m long based on:
        - Injection Bench
        (fall 2005, New Installation)
        - End Mirror




  September 11, 2007         F. Frasconi / INFN Pisa   5
          Detection System (scheme)
• Suspended bench with optics for
  beam adjustments and OMC                           External
• Detection, amplification and                        Bench
  demodulation on external bench




      Suspended
        Bench




  September 11, 2007       F. Frasconi / INFN Pisa          6
               Detection System             (cont.)

                                                      Output Mode-Cleaner




Suspended bench




  September 11, 2007    F. Frasconi / INFN Pisa                        7
                                                      External bench
                  Mirror Suspensions
• The Superattenuator (SA) is the
  mechanical system adopted to
  isolate the optical components
  from seismic activities (local
  disturbances). It is based on the
  working principle of a multistage
  pendulum.
• Thanks to the isolation
  performance the system is
  compliant with future detector
  upgrades.


  September 11, 2007     F. Frasconi / INFN Pisa   8
               Main features of SA

•Two types of SA: Short
Chains & Long Chains;
•Hybrid system: active
control below 4 Hz & passive
attenuation starting from 4
Hz;
•Measured attenuation
upper limit: 1015 at 10 Hz
(detection band extended in
the low frequency region)


September 11, 2007     F. Frasconi / INFN Pisa   9
         Mirror Suspension Control
• The Inverted Pendulum (IP) is
  the elastic structure
  conceived to allow a wide
  positioning control of the
  suspension point
• Hierarchical control of the
  mirror (3 actuation points):
   - Inertial Damping on IP (to control
   tidal strain and drift of any origin );
   - Local Control on Marionette
   (angular mirror displacements
   reduced down to fraction of mrad);
   - local damping on Reference Mass
   (RM).
September 11, 2007          F. Frasconi / INFN Pisa   10
Mirror Suspension Control improvements

• Several improvements have been done at the control
  level of the mirror:
  - global positioning IP control (GPIPC)
  - better stability for bad weather conditions –
  “guardian software” for earthquake oscillation



   high detector stability and high duty cycle



September 11, 2007   F. Frasconi / INFN Pisa           11
                Fall 2005 Shutdown

• The shutdown was suggested by a few major
  problems found during the commissioning
  phase:
  - control problems and alignment drift on PR
  mirror;
  - spurious resonances and back-scattered
  light on suspended IB (no possibility to
  operate ITF at full power).


September 11, 2007     F. Frasconi / INFN Pisa   12
   Fall 2005: detector upgrades (PR)

                                                    • Non-monolithic & Curved
350 mm



          120 mm
                                                      mirror induced:
                                   R=4100 mm          - control problems
 Incident
  beam                                                (spurious resonances);
                                                      - misalignment and jitter
                                                      noise for vertical
                                                      translations.

                                                         Monolithic flat mirror
         Old
         New
                                                                    &
     PR mirror transfer function                         Parabolic telescope on IB
 September 11, 2007                     F. Frasconi / INFN Pisa                 13
 Fall 2005: detector upgrades (IB)

• New suspended IB
  characteristics:
  - Faraday isolator
  (fixing back-scattered light)
  - parabolic telescope
  - thinner monolithic
  suspension wires

                                                   Faraday
                                                   Isolator




September 11, 2007       F. Frasconi / INFN Pisa              14
            Activities before VSR1

• Commissioning activity & noise hunting
  important for:      improve controls & automation
                      improve detector reliability & robustness
• Week-end Science run
       WSR1 (Sept. 2006)-WSR10 (Mar. 2007)
       important for: test shift organization
                      data collection
• Collected data
  used for:   detector characterization
              data analysis playground
              prepare joint analysis with LIGO


September 11, 2007       F. Frasconi / INFN Pisa                  15
     Detector sensitivity evolution




September 11, 2007   F. Frasconi / INFN Pisa   16
The First Virgo Science Run (VSR1)
• The run started on 18th May 2007
• It will last 4 months (till end of Sept. 2007)
• In coincidence with the last period of LIGO S5 run




September 11, 2007   F. Frasconi / INFN Pisa           17
 Improved sensitivity during VSR1

                     Sensitivity during VSR1: Sept. 5, 2007
                     Sensitivity during VSR1: May 18, 2007




September 11, 2007      F. Frasconi / INFN Pisa               18
  VSR1 horizon for inspiral sources

  Mpc           BNS inspiral range: ~4.0 Mpc




September 11, 2007          F. Frasconi / INFN Pisa   19
           VSR1: detector statistic




September 11, 2007   F. Frasconi / INFN Pisa   20
                 Data Analysis (DA)

• LSC-VIRGO agreement on common data taking & DA
  has been signed
• Data exchange has been activated since May 2007
  (start of VSR1)
• Organization:
  - DA groups have been merged (joint review committee
  created for each working group);
  - Joint DA committee and run planning committee have
  been created (discussing the DA activities and run
  schedule even after VSR1/S5)
• Final goal: LSC-VIRGO joint analysis
      - white paper in progress

September 11, 2007      F. Frasconi / INFN Pisa    21
                     After VSR1

• VIRGO is competitive at high frequency with LIGO
  detectors;
• VIRGO has the best sensitivity at low frequency
  (below 40 Hz)
  even if: the design sensitivity is still far away in the
  low-medium frequency range.
• Future activities:
  - a better understanding of the detector behavior
  - starting a detector upgrades campaign (VIRGO+ &
  AdV) to be implemented in parallel with other GW
  detectors all over the World (eLIGO & advLIGO).

September 11, 2007      F. Frasconi / INFN Pisa              22
                     VIRGO+

• Main goals:
  - improving the design sensitivity by a factor ~2
  - VIRGO+ should be back in Science Mode in 2009
  (second half) in coincidence with eLIGO
• VIRGO+ is meant as a series of detector upgrades:
  - new IMC payload (new end mirror: better optical
  quality & larger size)
  - thermal compensation system
  - higher laser power (laser amplifier by LZH/GEO)
  - new mirrors (reduced losses -> higher finesse)
  - new control electronics

September 11, 2007     F. Frasconi / INFN Pisa        23
            Advanced VIRGO (AdV)

• Goals
   - improving the VIRGO design sensitivity by a factor ~10
   - back in data taking around 2013-2014
• Main scheduled changes:
   - higher power laser (optical readout noise)
   - heavier mirrors (optical readout noise)
   - better coatings (thermal noise)
   - signal recycling (shape the sensitivity curve)
   - beam waist position (thermal noise)
• AdV Conceptual Design document in preparation
• The exact AdV upgrades still under discussion

September 11, 2007         F. Frasconi / INFN Pisa            24
                      Conclusions
• VIRGO still in Science Mode
  - VSR1 started in May: data taking 4 months long
  - very good detector stability (thanks to control improvements)
  - good duty cycle in science mode (~ 82%)
  - 18 locking periods longer than 40 hours
  - BNS inspiral range at 4.0 Mpc level
• VIRGO+ upgrades
  - improving the design sensitivity of a factor ~2: preparation in
  advanced status
  - commissioning period of the upgrades -> back in science mode
  within the second half of 2009 (in coincidence with eLIGO)
• AdV upgrades
  - working groups & coordinators: defined
  - improving the design sensitivity of a factor ~10: conceptual design
  document in progress to be submitted to the Funding Institutions
  by the end of the year
 September 11, 2007         F. Frasconi / INFN Pisa                   25

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:9
posted:10/13/2011
language:English
pages:25