F2f meeting
27 September, 2010
Overview of iLCGT & bLCGT
Kazuaki Kuroda
LCGT Collaboration
• This meeting is the first kick-off meeting of
• Objective of this f2f meeting
– Confirmation of policy and execution
– Recognition of collaborators and mutual
– Sharing information & ideas for construction
– Coordinating activities of sub-working groups
• Overview of iLCGT & bLCGT
– Objective, Design, Organization, R&D etc.
LCGT has been funded
• Japanese government bravely decided to
construct LCGT (June, 2010)
– Due to its significance of fundamental science with its
unique features of underground and cryogenics
• It is anticipated to firstly detect gravitational wave
– Its uniqueness will promise the first discovery and
may lead to the basis of the third generation detector
• It is also expected to play a key role in the
worldwide GW network
– Adv. LIGO and Adv. Virgo have similar sensitivity
The role of LCGT in the world-wide 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)
Sensitivity of LCGT and future improvement
This figure will be revised
soon by new design
Location of LCGT
LCGT is planed to be built underground at
Kamioka, where the prototype CLIO detector
is placed.
The Characteristic of LCGT
• The interferometer of LCGT belongs to the first generation
– operated at underground environment
– utilizing cryogenics
• Cryogenic leaves the optical design of LCGT rather
– 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
• No new advanced technology for cryogenic mirror system
– Traditional cryogenic technique available
– However, mirror exposed to room temperature wall
Optical design of LCGT (main part)
Beam radius 3cm
These main parameters determine
backbone of optical configuration and
reachable sensitivity
Beam radius 3cm
Plans of optical configuration:
introduction of v-RSE
Achieved results by TAMA and CLIO
TAMA in 2008 (improved after installation of SAS)
300 m arm length
CLIO at cryo temperature, 2010/3/7
100 m arm length
4 km
CLIO limit by room
LCGT design, 3 km
Schedule of LCGT coincides with the original GWIC roadmap
Edited in November, 2009
Construction schedule
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
Support from overseas projects
• Requests to LIGO for introducing its advanced
techniques and manpower
– Negotiation ongoing to make an Attachment under existing
academic research MOU (LCGT requests several items)
• Requests to Virgo for its advanced techniques and
– Start to make MOU for technical research collaboration
• Request to GEO for its advanced techniques and
– Preparing for making MOU for stronger collaboration
• Request to AIGO for its advanced techniques and
– Seeking possible research collaboration

ICRR-LIGO-lab meeting Additive reference material