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