Transcript A broad band detector of GW: The dual torus:

Future plans for
resonant detectors
Viviana Fafone
INFN - LNF
www.lnf.infn.it/esperimenti/rog
V. Fafone
ILIAS meeting
Mallorca 2005
Leiden
CERN RE 5
MiniGrail
LNF INFN
LNL INFN
V. Fafone
ILIAS meeting
Mallorca 2005
New devices and methods are now available
Readout systems:
• Superconductive amplifier sensitivity improved by a factor of 100
• Optical and parametric readout for acoustic detectors
FEM analysis:
• Used to improve suspension system design
• Wideband readout design
Test masses:
• Methods to develop large masses (100 ton)
• New high cross section materials
V. Fafone
ILIAS meeting
Mallorca 2005
EXPLORER
WIDENING THE BAND…
1998
NAUTILUS
10-20
2001
2001
880
950
AURIGA
2003
10-20
1999
V. Fafone
2003
ILIAS meeting
Mallorca 2005
•The duty cycle is limited mainly by cryogenic operations and
for most of the time is about 90%
•The apparata show constant performances.
•The data are not affected by human activity in the lab.
NAUTILUS DATA TAKING DURING 2005
3·10-19
No veto
applied
V. Fafone
ILIAS meeting
Mallorca 2005
Noise budget is well understood
Present Status of EXPLORER
reference signal
•Present limit from
amplifier noise
Teff~ 2mK
h ~ 3 10-19
V. Fafone
ILIAS meeting
Mallorca 2005
Present Status of AURIGA
one-sided Shh AURIGA T=4.5K
1x10
- noise prediction
- mechanical thermal - LC thermal
- SQUID back action - SQUID additive
Very good
agreement with
noise predictions
-20
-1/2
[Hz ]
1x10
-19
Shh
0.5
all these noise
sources will scale
with
temperature
1x10
-21
1x10
-22
800
850
900
950
1000
Frequency [Hz]
V. Fafone
ILIAS meeting
Mallorca 2005
To improve sensitivity:
• We need to improve the peak spectral sensitivity
- Increase M
: large and/or multimode detectors
- Reduce T/Q
: ultracryogenics. Low-loss materials
• We need to increase the bandwidth
- Increase the coupling of the e.m. transducer
- Reduce the noise temperature of the amplifier (double
SQUIDs)
V. Fafone
ILIAS meeting
Mallorca 2005
Sh for AURIGA @ 0.2K, capacitive
transducer
M3 - R. Parodi
INFN Genova
Sh for NAUTILUS @ 0.1K, parametric
transducer (m = 1 kg)
Teff ≈ 6 mK, sensitivity < 1·10-21 /√Hz over
about 50 Hz.
V. Fafone
ILIAS meeting
Mallorca 2005
TOWARDS MORE POWERFUL AND SENSITIVE
ACOUSTIC DETECTORS
V. Fafone
ILIAS meeting
Mallorca 2005
GWIC
Scenario for future detectors in the resonant-mass field
“…This paper suggests the following scenario for future detector development in
this field:
•In the medium-term, the realization of a spherical detector, to be proposed now
to the funding agencies,
•In the longer term, research toward wideband resonant detectors using Dual
Detection techniques.
V. Fafone
ILIAS meeting
Mallorca 2005
GWIC
Scenario for future detectors in the resonant-mass field
A spherical detector can make use of the state of the art readout
technology, developed for the bars and for MiniGrail, profiting from a larger
mass and from the omnidirectional nature of the spherical detectors. Such a
detector could have a sensitivity competitive with VIRGO and LIGO in the 1
kHz region. And since it allows full sky coverage during all observation time,
and determination of the source direction, it can have an important role in a
coordinated coincidence search. Since the principles of operation and
technology are well understood, a funding proposal could be prepared soon.
Research and development work on wideband resonant detectors using Dual
Detection techniques is valuable because it offers the potential for a
detector having unprecedented sensitivity in the band 1 to 7 kHz. …”
V. Fafone
ILIAS meeting
Mallorca 2005
sensitivities in the 2006 - 2012 prospective
The sphere has a quality factor due to the isotropy not shown in the plot
GEO
adv LIGO/adv VIRGO
V. Fafone
ILIAS meeting
Mallorca 2005
Properties of spherical detectors: a summary…
Thanks its five quadrupolar modes, equally sensitive to
gravitational waves:
•Reconstruction of the metric tensor
(polarization states and arrival direction)
•Omnidirectionality
•Multi-frequency capability
•Testing different metric theories of gravity
V. Fafone
ILIAS meeting
Mallorca 2005
The experimental situation
1. MiniGRAIL
-
Fast cooling of large masses (60 mK already
achieved)
-
Investigation of new material (CuAl 6%) Q’s, effect of the suspension and trx
fabrication
- Coupling of transducers
with the sphere
V. Fafone
ILIAS meeting
Mallorca 2005
The experimental situation
2. TIGA experiments
•TIGA arrangements
•TIGA experiments
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ILIAS meeting
Mallorca 2005
To allow the detection and identification of GW signals it is
useful to complement the IFO network with an advanced
resonant-mass observatory
Added value
• Duty cycle
• Sky coverage
• Instruments based on different principles
Strategy:
Realization of a Resonant-mass GW Observatory
Complementing the IFO Network
VIRGO - SFERA 2m
first hybrid observatory
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ILIAS meeting
Mallorca 2005
The short term proposed detector: SFERA
2 m dia, CuAl
M = 33 tons
f1 = 1.0 kHz
f2 = 1.9 kHz
The Collaboration
INFN (I)
University of Geneva (CH)
University of Leiden (NL)
Cost ~ 3 MEURO
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ILIAS meeting
Mallorca 2005
Pulse tubes
3He pumping tube
80 K radiation shield
4 K radiation shield
Joule-Thomson heat exchanger
700 mK radiation shield
50 mK radiation shield
still
Continuous heat exchanger
50 mK plate
Sintered heat exchanger
Mixing chamber
C2 - G. Frossati,
Leiden
V. Fafone
ILIAS meeting
Mallorca 2005
M6 - G. Mazzitelli,
INFN - LNF
At the final sensitivity an underground location will be probably necessary,
to avoid cosmic ray noise
V. Fafone
ILIAS meeting
Mallorca 2005
SFERA
If funded in January 2006
Assembling and tests during 2006-2007
Commissioning at the beginning of 2008
Science Run at the beginning of 2009
V. Fafone
ILIAS meeting
Mallorca 2005
Dual R&D: a full open bandwidth acoustic detector
INFN and Dept of Physics: Firenze – Legnaro - Padova – Trento - Urbino
DUAL detector is based on new ideas
1 – Wideband transducer: read displacement signal between two
massive resonator
- M. Cerdonio et al. Phys. Rev. Lett. 87 031101 (2001)
Avoid resonant bandwidh limit and thermal noise
contribution by the resonant transducer
2 - Selective readout: only GW sensitive normal modes must be
measured
- M. Bonaldi et al. Phys. Rev. D 68 102004 (2003)
Reduce overall thermal noise by rejecting the
contribution of not useful modes
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ILIAS meeting
Mallorca 2005
Dual: Main
Concept
Measurement of
differential
deformations of two
nested resonators
The outer
resonator is
driven above
resonance
The inner
resonator is
driven below
frequency
π Phase
difference
5.0 kHz
Intermediate
GW broadband
V. Fafone
ILIAS meeting
Mallorca 2005
Mode selection strategy
Geometrically based
mode selection
Large interrogation
regions
Bandwidth free from
acoustic modes not
sensitive to GW
Reject high
frequency resonant
modes which do not
carry any GW signal
2-D Quadrupolar filter:
X=X1 +X3 –X2 –X4
Capacitive transducer
design
Also FFP optical scheme
F. Marin et.al, Phys. Lett. A
309, 15 (2003)
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ILIAS meeting
Mallorca 2005
Evaluated sensitivity (SQL)
Mo Dual 16.4 ton height 3.0m
0.94m
SiC Dual 62.2 ton height 3.0m
2.9m
Q/T=2x108 K-1
M. Bonaldi et al.
Phys. Rev. D 68 102004 (2003)
Antenna pattern: like 2 IFOs
colocated and rotated by 45°
V. Fafone
ILIAS meeting
Mallorca 2005
DUAL is based on
a deep revision of the resonant detector design
AND
a challenging R&D on readout systems
(Some topics are tackled
within STREGA)
Timeline
R&D: 2005-2008
Detailed design: 2008-2009
V. Fafone
ILIAS meeting
Mallorca 2005
Selective readout system for DUAL:
mechanical amplification stage
• Broadband amplification (5.0 kHz)
• Displacement gain factor about 10
• Negligible intrinsic thermal noise
• Compliance
Optic readout
T3 - P. Falferi,
IFN Trento
Leverage type
amplifier
Capacitive readout
Fabry-Perot
mirrors
Electric
Field
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ILIAS meeting
Mallorca 2005
Progress towards a wide area optical readout
Usual cm-long cavities have small spot size (1mm)
→ higher order acoustic modes of the real system contribute to the noise
To average out the noise, we
need a spot size > 10 cm !!!!
M3
M4
Folded Fabry-Perot: FFP
Phys. Lett. A 309, 15 (2003)
M1
effective increase
of spot size
D
M2
relative shot noise limited displacement sensitivity: constant
T3 - P. Falferi
relative freq. noise due to Brownian noise
1/ N
relative freq. noise due to rad pressure noise  1/N2
INFN Firenze
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ILIAS meeting
Mallorca 2005
• Bias voltage in the 100 MV/m range
- surface finishing effect
- electrodes conditioning procedure
- effect of dielectric films
Two axis
Goal: 108 V/m
Achieved: 107 V/m
Apparatus for
High voltage
breakdown study
adjustment
Measurement of
V.B. of aluminum
polished surfaces of
cylindrical samples
Linear vertical
stage
M2 - J.P. Zendri,
IFN Trento
V. Fafone
ILIAS meeting
Mallorca 2005
Test mass material characterization
Low temperature measurements of the Q factor of
ceramic materials
M2 - J.P. Zendri,
INFN Legnaro
V. Fafone
ILIAS meeting
Mallorca 2005
V. Fafone
ILIAS meeting
Mallorca 2005