The AURIGA experiment: updates and prospects

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The AURIGA experiment updates and prospects
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BAGGIO Lucio ICRR on behalf of AURIGA
collaboration
The AURIGA detector re-started data taking in Dec
2003, after 4 years of research and developement,
in order to improve the sensitivity. A brief
overview of the results during last year will be
given. Present international collaborations and
future prospects will be reviewed.
lbaggio_at_icrr.u-tokyo.ac.jp
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Topics of this presentation
The AURIGA experiment run 2
Characteristics and setup of the second run
(after Dec 2003)
Burst analysis
Main issues with burst search duty cycle,
detection efficiency, background events
Collaborations
Memorandum of Understanding with LIGO, IGEC-2
agreement, contacts with VIRGO
Other activities
New cryogenic detector with optical transducer
the DUAL project
Next steps and Summary
New low-frequency suspensions, ultra-cryogenic
cooling,
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The AURIGA experiment run 2
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Old New AURIGA detector
1997/06
Cryogenic failure
1999/12
RD
2003/12
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Main upgrades for the 2nd run

• New mechanical suspensions
• attenuation gt 360 dB at 1 kHz
• FEM modelled
• 3 resonant modes operation
• two mechanical modes
• one electrical mode
• New data analysis and data acquisition
• C object oriented code
• frame data format
• Monte Carlo software injections (internal or
  MDC)
• improved noise matching algorithm
• selectable templates

New suspension system for the gravitational wave
bar detector AURIGA (in preparation, to be
submitted to Rev. Sc. Inst.)
3-mode detection for widening the bandwidth of
resonant gravitational wave detectors L. Baggio,
M. Bignotto, M. Bonaldi, M. Cerdonio, L. Conti,
P. Falferi, N. Liguori, A. Marin, R. Mezzena, A.
Ortolan, S. Poggi, G. A. Prodi, F. Salemi, G.
Soranzo, L. Taffarello, G. Vedovato, A. Vinante,
S. Vitale, and J. P. Zendri (submitted to Phys.
Rev D.)
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The new suspension system (1)
Attenuation Internal modes frequency (-240DB
wide band ? FEM)
Quality factor
Yield strength (no more than 25 to avoid creeps)
Ultracryogenic (0.1 K) compatibility (no thermal
short-circuit with 4K container, good thermal
link to diluition refrigerator)
Vacuum compatibility (10-6mb ? no rubber)
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The new suspension system (2)
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New transducer amplifier

• three resonant modes operation
• two mechanical modes
• one electrical mode

• transducer bias field 8 MV/m

• new SQUID amplifier
• double stage SQUID
• 650 ? energy resolution at 4.5 K in the detector

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Raw data calibration
Mechanical transfer function (response to force
applied by a electromechanical actuator attached
to the bar)
Fully-automatic adaptive noise matching algorithm
enbedded in AURIGA data analysis
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Frequency Hz
Fit of the psd with ARMA noise model
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Temperature of normal modes
mode 1
mode 2
mode 3
T K
date 13-15 Nov. 2004
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Noise budget expected at 4.5K
single-sided Shh
Very good agreement with noise predictions
All these noise sources will scale with
temperature
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Burst analysis(matched filter)
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Typical sensitivity to bursts
Template
2004, Nov 13-15 (weekend)
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Time of arrival error estimate (Monte Carlo)
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Unexpected non-linear, non stationary noise

• unmodeled spurious noise peaks within the
  sensitivity bandwidth
• not related to the dynamical linear response of
  the detector
• non gaussian statistics
• related to mechanical external disturbances
• ?up-conversion of low frequency noise

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Epoch vetoes and goodness-of-fit tests
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Background events approaching the gaussian tail
Amplitude distribution of events AURIGA Nov.
13-14, 2004
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Duty cycle
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Additional room-temperature vibration attenuators
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Performances after the upgrade of suspensions
10 days of stationary gaussian operation lt 2
outliers/day 60 duty cycle for gaussian
data
Experimental data Simulated data (gaussian noise)
2004 Dec 03-13 (after vetoes)
counts
SNR
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Collaborations
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International Gravitational Event Collaboration
AURIGA is member of the IGEC since its foundation
in 1997. IGEC HP http//igec.lnl.infn.it Main
results in P. Astone et al., Methods and
results of the IGEC search for burst
gravitational waves in the years1997-2000, Phys.
Rev. D 68 (2003) 022001 (also on astro-ph/0302482)
IGEC-2 Agreement, Jan 17th 2005  The groups
running the four bar detectors ALLEGRO, AURIGA,
EXPLORER, NAUTILUS have signed a Letter of Intent
to perform a new joint observation starting from
2004 available data. The approach of this new
joint observation, will be based on the previous
IGEC experience. The observation times of the
participating detectors will be coordinated.
IGEC-2 is open to agreements with other projects
sharing the same scientific objectives.
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LIGO-AURIGA MoU
A Memorandum of understanding between the
experiment AURIGA and the LIGO project has been
recently signed, for the purposes of joint data
analysis and dissemination of results
2004/07/12 LIGO-M040010-00-M (MoU) 2004/07/12
LIGO-M040191-00-M (Attachment 1) 2004/07/12
LIGO-M040198-00-M (Membership list)
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Joint LIGO-AURIGA working group activity
STEP-ZERO Outline of the most interesting
analysis to be performed based on preliminary
study of sensitivity and efficiency of the
detectors
Document Type LIGO-T040202-00 2004/10/13 Proposal
for the First AURIGA-LIGO Joint Analysis L.
Baggio, L Cadonati, S. Heng, W. Johnson, A. Mion,
S. Poggi, G.A. Prodi, A. Ortolan, F. Salemi,
P. Sutton, G.Vedovato, M. Zanolin
1st STEP Cross-correlation between LIGOs (L1, H1
H2) around the times of AURIGA triggers ?
Analysis of S3 data in progress
2nd STEP Implementation of IGEC-like analysis
(self adapting directional coincidence search
between candidate event lists from each detector)
ltin preparation gt
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LIGO-AURIGA MoU

• A working group for the joint burst search in
  LIGO and AURIGA has been formed, with the purpose
  to
• develop methodologies for bar/interferometer
  searches, to be tested on real data
• time coincidence, triggered based search on a
  2-week coincidence period (Dec 24, 2003 Jan 9,
  2004)
• explore coherent methods

best single-sided PSD
Simulations and methodological studies are in
progress.
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White paper on joint analysis
Two methods will be explored in parallel

• Method 1
• IGEC style, but with a new definition of
  consistent amplitude estimator in order to face
  the radically different spectral densities of the
  two kind of detectors (interferometers and bars).
  
• To fully exploit IGEC philosophy, as the
  detectors are not parallel, polarization effects
  should be taken into account (multiple trials on
  polarization grid).

• Method 2
• No assumptions are made on direction or
  waveform.
• A CorrPower search (see poster) is applied to
  the LIGO interferometers around the time of the
  AURIGA triggers.
• Efficiency for classes of waveforms and source
  population is performed through Monte Carlo
  simulation, LIGO-style (see talks by Zweizig,
  Yakushin, Klimenko).
• The accidental rate (background) is obtained
  with unphysical time-shifts between data streams.

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Other activities
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Optical readout for a bar detector
Transducer cavity a Fabry-Perot cavity between
the bar and the resonant Reference cavity a
stable Fabry-Perot cavity acting as length
reference Laser frequency locked to the
reference cavity Working principle Variations
of the transducer cavity length are measured by
the stabilized laser
bar
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Room temperature prototype (2001)
The readout mechanics
The reference cavity
L 110 mm, FSR 1.36 GHz, F 44000
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Sensitivity of the room temperature prototype
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New detector with cryogenic optical transducer (1)
Sensitivity predicted at T4K with already
developed technology
Goal acquire data from a cryogenic bar equipped
with the optical readout

• New transducer mechanics
• New bench on top of the bar with
  cryogenic-compliant motorized mounts for optics
• New cryogenic-compliant bar suspension
• New clean vacuum system
• New anechoic housing for the laser optical bench
  
• Higher finesse cavity

The new reference cavity
TO DO New cryogenic bar housing (in
progress) Transducer with optimized mass (after
first tests)
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New detector with cryogenic optical transducer (2)
adaptater pre-attenuation
cables and optical phiber thermalization Lhe
vessel
single-column cryogenic suspension
Direct thermal links from the Lhe vessel
Roadmap April delivery of the cryogenic
container Summer assembling and testing Autumn
commissioning of the complete detector 2006
first measures
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DUAL concept
Two possible configurations
Measurement of differential deformations of two
nested bodies, resonating at different
frequencies and both sensitive to the gw signal
Dual sphere
PRL 87 (2001) 031101
antenna pattern
isotropic
Dual cylinder
PRD 68 (2003) 102004
antenna pattern
identical to that of 2 interferometers at 45
degrees with respect to each other

• In the intermediate frequency range
• the outer resonator is driven above resonance,
• the inner resonator is driven below resonance
• ? phase difference of ?

In the differential measurement ? the
signals sum up ? the readout back
action noise subtracts
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DUAL predicted sensitivity
Q/T gt 2 108 K-1 , Standard Quantum Limit

• Current activity
• Detector design
• seismic noise control (pre-filtering)
• high frequency (in band) mechanical
• vibration filtering
• underground operation
• Readout system
• Requirement 5x10-23 m/vHz
• Two concurrent studies capacitive (SQUID) and
  optical (folded Fabry-Perot, Phys. Lett. A 309,
  15 (2003) ) readout

Mo Dual 16.4 ton height 2.3 m Ø 0.94m
SiC Dual 62.2 ton height 3 m Ø 2.9m
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Next steps
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New low frequency vibrational damping
New external suspensions fast assembling in
April-June
Air springs effective above1-2 Hz
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Past, present and future sensitivity
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Further steps to increase the bandwidth
T 0.1K T 0.1K and bias field x2.5
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Detector sensitivity comparison