Transcript Slides - Agenda INFN

Status of LCGT project
3rd ET meeting@Budapest
23-November, 2010
Kazuaki Kuroda
On behalf of LCGT
Collaboration
Objective of LCGT
• LCGT plans to take part in the race of the first
detection of gravitational wave
– Its uniqueness may lead to the basis of the
third generation detector
• It is also expected to play a key station in Asia
in the worldwide GW network
– Adv. LIGO and Adv. Virgo have similar sensitivity.
GEOHF will cover high frequency region.
Higher priority
Target GW Sources of LCGT
1. Coalescence of neutron star binaries
2. Coalescence of black hole binaries
3. Core collapse of massive stars
4. Rotation of pulsar
Existing neutron star binaries in our Galaxy
• PSR B1913+16
• PSR B1534+12
• PSR J0737-3039
• PSR J1756-2251
• PSR J1906+0746
coalescence
chirp signal
-300Hz
quasi-mode
oscillation
-1kHz
msec
Sensitivity of LCGT and future improvement
This figure will be revised
soon by new design
ＬＣＧＴ in World-wide GW Network
１）Increase the large baseline length （20 ms time flight among North America,
Europe and Asia）
２）Widen the sensitivity pattern
Adding LCGT to L/H-L/L-Virgo, the whole sky coverage is realized
33% coverage
100% coverage
By global network
@B. Schutz(Fujihara seminar, May 2009)
Characteristics of LCGT
• The interferometer of LCGT belongs to the second and half
generation detector
– operated underground environment
– utilizing cryogenics
• Cryogenic leaves the optical design of LCGT rather
conservative
– Traditional size of the beam (no need of larger optics)
– Less thermal lens effect (no need of TCS system on main mirror)
– Less serious optical instability
• New advanced technologies arising from cryogenic mirror
system
– Mirror exposed to room temperature wall
– Quiet refrigerator system is needed
The merit of underground
At Kamioka low frequency noise is less than TAMA site by 30
times.
20m Prototype detector installed
The seismic noise of Mitaka is
equivalent to continuous blasting in Kamioka underground.
Merit of Underground
20m prototype interferometer was moved
from Mitaka to Kamioka underground in 1998
Displacement spectrum m/RHz
Blue: at Mitaka
Red: underground Kamioka
Green: limit by isolation system
Hz
Achieved sensitivity by TAMA
• Almost all noise sources that limit TAMA sensitivity have been recognized.
• Low frequency region of TAMA sensitivity is limited by up-conversion noise
Cooling test
Cryogenic mirror was established
by several basic experiments.
Contamination test
Mechanical Q test
Quiet Refrigerator system with anti-vibration system
Cryostat used in CLIO
at the factory of Toshiba
(in 2003)
Heat radiated by cold surface was
Not correctly considered in design
Heat reflected by cold surface
was correctly calculated
by simulation, which coincided well
with experiment
This is utilized in LCGT
Achieved thermal noise limit by CLIO
Mirror suspension thermal
--inversely proportional to f 2.5
Displacement noise 1/√Hz
Thermal noise limit by eddy
current damping between actuator
magnets and metal solenoid holder
--inversely proportional to f 2
This thermal limit at room
temperature was broken
by cryogenics in March, 2010
Mirror thermal
Frequency
Quality selection device of sapphire substrate
In order to cope with large optical loss of sapphire substrate,
quality selection of sapphire pieces has been developed.
LIGO sapphire substrate, 250mm in diameter
29kg lent by the courtesy of LIGO.
Auto scanning birefringence device
Initial and baseline LCGT
• Initial LCGT without cryogenic mirror will be operated
by October, 2014, in order to show an engineering
result (First Step that should be fulfilled)
• The initial LCGT forms the main part of Baseline LCGT
(except recycling and cryogenics)
• Synthesized silica for the initial LCGT mirror and
sapphire for the baseline LCGT
• Since cryostats cannot be physically installed after the
initial LCGT, the main bodies of cryostats are installed
at the first stage
• Tall anti-vibration system may be installed in the first
phase
LCGT Organization for Construction
LCGT: Time line (Budget)
We will hear the final
decision at the end of 2010.
Optical design of LCGT (main part)
Beam radius 3cm
These main parameters determine
backbone of optical configuration and
reachable sensitivity
Beam radius 3cm
Design parameters
In order to attain the sensitivity to catch the event at ~250Mpc,
we need ~800kW optical power (~400 kW each cavity) to reduce
shot noise.
Thermal noise of the mirror, coating of the mirror, and
suspension need to be suppressed by cryogenic temperature,
20K. Mechanical losses of these parts are required to satisfy
this thermal noise limit; they are10-8, 4X10-4, 10-8
Final sensitivity is
800kW
limited by quantum noises
in the observation frequency
band, 230Hz. Radiation
pressure noise is determined
both by the optical power
and by mass, 30kg.
Design of Vacuum system (Center room)
①
Three types of anti-vibration system
Type A) SAS(GASF 3stage)+cryo-sus: ITMX, ITMY, ETMX, ETMY
Type B) SAS(GASF 2stage)+non-cryo: BS, PR2, PR3, SR2, SR3, MC2F, MC2E
Type C) STACK+2stages:
MC1F, MC1E, MMT, PD
2m
4.3 m
1-2 m
3m
2.5+2.45 m
2m
Data Analysis
• It is difficult to detect burst wave events by a
single detector
• Coherent observation gives more fruitful
result
• It is natural to promote data-sharing in the
world-wide GW observation network
• We have experienced data taking & analysis
by TAMA and CLIO
• Need to find flexible way to satisfy
requirements of both program and science
Projects underground at Kamioka
LCGT is planed to be built underground at
Kamioka, where the prototype CLIO detector
is placed.
Schedule of LCGT coincides with the original GWIC roadmap
Edited in November, 2009
Construction schedule
International collaborations with other
projects
• Attachment agreed under existing MOU
between ICRR (represents LCGT Collaboration)
and LIGO laboratory
– Manpower, software & technique exchanged
• MOU with Attachment between VIRGO (EGO +
Virgo Collaboration) and ICRR is now on
process to be signed
• MOU between ICRR and GEO people is also
conceived
Summary
• LCGT has been partially funded (June, 2010)
to promote fundamental physics by GW
detection
• LCGT is expected to play a key role in the
worldwide GW network with adv. LIGO, adv.
Virgo and possible other observatories
• LCGT will become a prototype model of ET
• Researchers who are interested in the
gravitational wave astronomy and LCGT from
overseas are welcome to LCGT