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Large scale CryogenicGravitational wave Telescope- Overview and status of cryogenics -
T. SuzukiHigh Energy Accelerator Research Organization
LCGT Collaboration
Recontres de MoriondGravitational Waves and Experimental Gravity
La Thuile , 20-27 March 2011
We express our thanks for warm massagesand supports after the earthquake in 11Mar 2011.
Fortunately LCGT has no human loss from the unprecedented disaster.
Earthquake and tsunami destroyed cities and life along the Pacific coast of Iwate, Miyagi, Fukushima and Ibaraki prefectures.
Nuclear power plant in Fukushima lost emergency power supply for cooling system by tsunami.Nuclear fission chain reaction was stopped by the quake. Reactor core and spent fuel overheated. -> crisis
The 2011 off the Pacific coast of Tohoku Earthquake
A massive earthquake of magnitude of 9.0 occurred Friday 11March, off the Pacific coast of the northeastern part of the Japanese Main island, causing devastating damages.The Japan Meteorological Agency named this earthquake “The 2011 off the Pacific coast of Tohoku Earthquake”.
Date and Time: 11 March 2011 14:46JST(05:46UTC)Magnitude: 9.0 (The largest earthquake recorded in Japan)Hypocenter: 130km off the Pacific coast of Tohoku region, from Iwate to Ibaraki prefecture, 24km depth
38°6.2’N 142°51.6’EMechanism: Reverse fault type with WNW-ESE compressional axisIntensity: 7(Max.) : Krihara City of Miyagi Prefecture 6+ : 28 cities and towns in Miyagi, Fukushima, Ibaraki and Tochigi Prefectures 6 or weaker : Observed nationwide from Hokkaido to Kyushu
Hypocenter
Distribution of intensity 2011 Mar. 11
Japan Meteorological Agency
Tsunami damage
Fukushima daiichi Nuclear plant
Height of seawall: 7.9 m
The crest of tsunami was higher.
14 m at Fukushima, by the mark of water ?
Many wave recorders indicated out of range.
Many cities along the coast were damaged.
Nuclear power plants in Fukushima.Thermal power plants in Fukushima and Ibaraki.ー> Electric power shortage in 50 Hz area.
Damage of TAMA and CLIO
CLIO
TAMA
Hypocenter
Earthquake Research Institute, University of Tokyo
Maximum acceleration TAMA got serious damage
Three of the four mirrors fell onto the breadboard.
R.Takahashi
CLIOMC lost lock within a few seconds. This situation was lasting more than one hour.
No serious damage.
Influences of earthquake
• The restoration of devastated area affects apolicy and budget condition of the government.Influence for scientific projects are currentlyunpredictable.
• Electric shortage causes a severe factor ofsuppressing activities for industries and life.Also research activity of universities andinstitutes are mostly forced to stop at present.
• We should do our best to keep the plannedschedule of construction as well as the start ofa run in 2017.
Overview of LCGT
Large-scale Cryogenic Gravitational wave TelescopeLCGT
Objectives1. Detect gravitational wave for the first time.2. Begin gravitational wave astronomy.
(1) Underground tunnel Ikenoyama, Kamioka From the surface Vertical > ~200m Horizontal > ~400m(2) Arm length 3km
(3) Cryogenic Mirrors T=20K, Sapphire M=30kg
Target: Inspiral of NeutronStar binary.
Construction start
June 2010 Construction cost was partially approved by the Facility for the advanced research program of Ministry of Education, Culture, Sports, Science and Technology.
¥9.8x109 for 3 years construction.( 63% of the original request for 7 years construction)
2011 Excavation cost was almost approved.
Budgetary request continue for full construction of LCGT.
ScheduleM.Ando
iLCGT Excavation, surveying, installation and alignment.Leak test of vacuum system. Long baseline FPM interferometer at 300K operation.Engineering run in short period (~ 1 month (TBD))
bLCGT Upgraded vibration isolation system.RSE interferometer.Equip cryogenics.
OBS Detector tuning and run in long-term.Details under discussion
LCGT tunnel
Mozumi
Atot
su
T.Uchiyama
Detector parametersM.Ando
InterferometerM.Ando
Sensitivity M.Ando
Observable range
Detection rateM.Ando
Sky coverage and network
K.Kuroda
Data analysis
N.KandaD.TatsumiM.Ando
Organization
K.Kuroda
Review categories• Internal review
– Design, schedule, construction process of each subsystem– Total 15 reviews held in Dec. 2010 ~ Feb. 2011
• External review– Design, schedule, technology, interface of each subsystem– Reviewers: Experts in the GW field– Held in 28 Feb. ~ 4 Mar.– Report submitted in 12 Mar.
• Program advisory board– Management, progress, consistency of the project– Reviewers: In the GW field and neighboring field.– Will be held in June 2011.
International collaborations with other projects• LIGO laboratory
– Attachment agreed under existing MOU between ICRR (representsLCGT collaboration) and LIGO laboratory.
– Manpower, software and technique exchanged.• VIRGO
– MOU with attachment between VIRGO (EGO+Virgo collaboration )and ICRR was signed.
• GEO– MOU between ICRR and GEO people is also conceived.
• ET– Cooperative research vibration isolation and cryogenics.
• SUCA (China)– MOU between ICRR and Shanhai Normal University, SUCA is on
the process of agreement.• Korea
– Collaboration with Korean researchers is conceived.
Status of LCGT cryogenics
Basic requirements for cryogenic system
Temperature of the test mass/mirror : 20 [K]
Cool the mirror without introducing excess noise, especially vibration due to cryocooler.
Construction plan of LCGT cryogenics
• Construct a prototype by the end of 2012fy in order todemonstrate the performance of cooling system andinvestigate interface to other subsystems.
• Real cryostat and cooling system will construct in theperiod of conversion from iLCGT to bLCGT.
• Mirror chambers of iLCGT are built as vacuum chamberfor the operation at 300 K. The mirror chamber of iLCGTwill be replaced by the real cryostat.
• In the budget for cryogenics until 2012fy, some criticalcomponents of cryocooler unit will be purchased inprecedence. It may prevent unavailability of componentsagainst withdrawal business .
Budgetary condition and construction plan of LCGT cryogenics
Design, manufacture componentsassemble•factory testtransport•install
design manufacture
TransportReplacementinstall
Cooler procurementPrelminary measurement
design manufacture assemble•factory test
Prototype cryostat
Cryostat of bLCGT
Vib. Isolattor(1W@4K)(4sets)
1W@4K Cooler
Design
Shield Duct
Shield Duct Cooler
procurement vibration measurement manufacture
Sapphire-SapphireSapphire-Silicon
Strength, thermal resistance, Thermal cycle tolerance, dissipation
Test model
designfabrication experiment
Real scale model
Scale up from test model ( with modification )
fabrication
Install test Cooling test
Fabrication
custody
2011fy 2012fy 2013fy 2014fy 2015fy 2016fy
Vib. Isolator design
manufacture assemble
custody
Shield Duct Cooler
manufactureVib. Isolator design
Procurement
Design
Shield Duct
manufacture assemble
assemble
AdjustmentMinor modification
Demonstration /Investigation of cryogenic system
Interface with other subsystemsConsistency of design
Mirror chambers of iLCGTtransport•install
custody
manufactureDesigniLCGT
Components• Cryostat
– Mirror chamber (Vacuumchamber)
– Cryo-shield (Radiation shield)– Heat links
• Heat conduction path– Heat conductor– Connection of conductors
• Low vibration cryocooler unit– Vibration isolator of cryocooler
• Pulse-tube cryocooler• Remote valve• Flexible heat links• Rigid frame for supporting stage
– Sound proof• Acoustic shield of compressor
room
• Shield duct– Cryocooler for cooling shield duct– Vibration isolator of cryocooler– Baffles to reflect or absorb obstacle
radiation• Thermal insulator
– Low degassing MLI ( or SI)– Optimum mounting
• Sapphire mirror suspension– Sapphire-sapphire bonding
technique– Compatibility to mirror polishing and
coating process– Interface with SAS platform– Low mechanical loss at bonded
boundary– Stability– Quality control
Shield duct φ800Shield duct φ800Gate valve
Gate valve
Connection to SAS
Low vibration cryocooler unit
Low vibration cryocooler unit
Cryostat
Location of Cryostat with shield duct for bLCGT
Prototype
Cryostat and cryocooler units
Main beam(1200mm FL)
S.Koike
to SAS
View ports
Remote valve
Low vibration cryocooler unit
Main LASER beam
φ2.4m
~3.8
m
CryostatStainless steel t20mmDiameter 2.4mHeight ~3.8mM ~ 10 ton
CryocoolersPulse tube, 60Hz1W at 4K (2nd)40W at 50K (1st)
Shield duct φ800
Low vibration cryocooler unit
Cryostat
Ana
log
elec
troni
cs
300K BBR
View port
mirror monitor
PrototypeLocation : room #34
• Optimize the 20m shield duct.• Cooling test. Evaluate heat loads.• Suspension install test.• Include cryogenic and its interfaced subsystems.• Verify a consistency of the integrated system• Feasible design for real cryogenic system.
Demonstration/investigation can be carried out independently of the main body of LCGT.
Summary• LCGT construction started.
– Cost was partially funded. Continue to request foradditional
• Aim to detect GW and to open new window of astronomyby making global network of observation.
• Demonstrate technology of underground and cryogenics.• Detailed design underway.• Prototype cryostat demonstrate the performance of cooling
system and investigate interface to other subsystems.Real cryostat for bLCGT will be installed by replacementfrom mirror chamber of iLCGT.
Thermal conductivity of SapphireT. Tomaru