Thermal Noise and Materials Coatings Optics Cryogenics Iain

Thermal Noise and Materials, Coatings, Optics, Cryogenics Iain Martin, Michele Punturo, Kazuhiro Yamamoto Institute for Gravitational Research, University of Glasgow INFN Perugia Institute for Cosmic Ray Research, the University of Tokyo 18 May 2014 Gravitational Wave Advanced Detector Workshop @ Alyeska Resort, Girdwood, Alaska, U. S. A. 1

0. Abstract Tuesday and Wednesday of this GWADW, there are four parallel sessions. One of them : Thermal noise workshop Outlines and topics are introduced. We need your help for vivid discussion ! 2

Contents 1. 2. 3. 4. 5. 6. 7. 8. 9. Introduction Short term upgrades Thermal noise modelling Towards cryogenic detector Cryogenics and Materials Flatter beams Coatings Posters Summary 3

1. Introduction Thermal noise : Fundamental noise source in precious measurement One of the serious issue in upgrade of interferometric gravitational wave detector In our workshop, idea, strategy, current hot topic about thermal noise will be discussed. K. Numata et al. , Physical Review Letters 91 (2003) 260602 2012 4

1. Introduction In our workshop, idea, strategy, current hot topic about thermal noise will be discussed. Our workshop consists of 7 sessions. In the first half of each session, invited speakers present “summary” talk to stimulate discussion. In the second half of each session, we discuss. In short, half of our workshop is for discussion. 5

1. Introduction Outline of program Tuesday morning Session A : Short term upgrades Session B : Thermal noise modelling Session C 1: Toward a cryogenic detector Tuesday afternoon Session C 2: Cryogenics and Materials Wednesday morning Session D: Flatter beams and coatings Wednesday afternoon Session E : Coatings Session F : Summary Thursday afternoon : Iain Martin reports summary. 6

2. Short term upgrades Room temperature second generation interferometer Fused silica mirror with IBS coating suspended by fused silica fibers 7

2. Short term upgrades Room temperature second generation interferometer Fused silica mirror with IBS coating suspended by fused silica fibers This has long history since GEO started development and is enough mature. C. Affeldt et al. , Classical and Quantum Gravity 31(2014)224002. What kinds of short term improvement is possible for Advanced LIGO and Advanced Virgo ? G. Hammond : Advanced detectors solutions for low thermal noise suspensions S. Penn : Advanced detectors solutions for low 8 thermal noise test masses

3. Thermal noise modelling 3 -1. Thermal noise model of reflective coating Coating itself is complicate system which consist of two kinds of material layers. Model construction is not easy. For example, does loss between layers matter ? NO : S. D. Penn et. al. , Classical and Quantum Gravity 20(2003)2917. YES (partially): M. Granata et. al. , GWADW 2012 https: //dcc. ligo. org/LIGO-G 1200618/public Current models, Limitations and possible improvements, Open questions. I. Pinto : Modelling thermal noise 9

3. Thermal noise modelling 3 -1. Thermal noise model of reflective coating For example, does friction between layers matter ? YES (partially): M. Granata et. al. , GWADW 2012 https: //dcc. ligo. org/LIGO-G 1200618/public 10

3. Thermal noise modelling 3 -2. Non thermal equilibrium steady state Fluctuation-Dissipation Theorem Relation between thermal noise and loss It is valid if the system is in thermal equilibrium. However, it could not be true in some cases. Some system is in steady state, but not thermal equilibrium. Example : Room temperature interferometer Temperature gradient in mirror Laser beam absorption Thermal Compensation System 11

3. Thermal noise modelling 3 -2. Non thermal equilibrium steady state Example : Cryogenic temperature interferometer KAGRA mirror suspended by sapphire fibers D. Chen Heat absorbed in mirror flows along fibers. 16 K Temperature gradient in fibers. 22 K 12

3. Thermal noise modelling 3 -2. Non thermal equilibrium steady state How much is it different from the Fluctuation. Dissipation Theorem ? How do we “improve” Fluctuation-Dissipation Theorem ? L. Conti : Thermal noise and Non-Equilibrium effects 13

3. Thermal noise modelling 3 -2. Non thermal equilibrium steady state L. Conti : Thermal noise and Non-Equilibrium effects L. Conti et al. , Classical and Quantum Gravity 27 (2010)084032. L. Conti et al. , Journal of Statistical Mechanics: Theory and Experiment (2013)P 12003. 14

4. Towards cryogenic detector Cryogenic is one of methods to reduce thermal noise. Amplitude of thermal noise is proportional to 1/2 (T/Q) 15

4. Towards cryogenic detector CLIO(CLIO, Cryogenic first generation) First cryogenic interferometric gravitational wave detector 100 m baselines 16

4. Towards cryogenic detector CLIO demonstrated the reduction of thermal noise by cooling mirrors T. Uchiyama et al. , Physical Review Letters 108 (2012) 141101. 17

4. Towards cryogenic detector KAGRA (Cryogenic second generation) First km-scale cryogenic interferometric gravitational wave detector Cryostat KAGRA site Y front cryostat Cryo duct Cryocooler (In total, four cryocoolers) Construction is in progress. 18

4. Towards cryogenic detector LIGO Voyager (Cryogenic 2. 5 generation ? ) Nicolas Smith, Rana Adhikari LSC meeting (March 2015) 19

4. Towards cryogenic detector Einstein Telescope (Cryogenic third generation) 20

4. Towards cryogenic detector Thermal fluctuation of vertical motion of suspended mirror is an issue. S. Reid: DLC coated silicon cantilever blade springs for improved vertical suspension thermal noise performance for future GW detectors 21

5. Cryogenics and Materials Cryogenic interferometer sounds attractive. However , there are some open issues. Cooling technologies should be considered carefully (operating temperature, cooling time, open questions …). K. Yamamoto : Cryogenic interferometer technologies 22

5. Cryogenics and Materials Room temperature second generation interferometer Fused silica mirror suspended by fused silica fibers (amorphous) This suspension is not a good for cryogenics because of large mechanical dissipation and low thermal conductivity at low temperature Other material with small dissipation and high thermal conductivity Sapphire or Silicon (Crystal) 23

5. Cryogenics and Materials Silicon bulk Sapphire bulk for KAGRA About 220 mm diameter, 150 mm thickness 450 mm 300 mm Harald Lueck(ELi. TES meeting 2013) https: //events. egogw. it/indico/conference. Other. Views. py? view=standard&conf. I d=7 Source: http: //www. iisb. fraunhofer. de/content/dam/iisb/de/images/geschaef tsfelder/halbleiterfertigungsgeraete_und_methoden/gadest_2011/ R. Nawrodt : Materials for suspensions and test masses in a cryogenic detector 24

5. Cryogenics and Materials Absorption in mirror is a crucial issue (In the worst case, mirror can not be cooled !) J. Degallaix: Optical Absorption on substrates 25

6. Flatter beams Larger beam is one of method to reduce thermal noise. When beam is larger, thermal fluctuation in wider area is averaged. Since correlation between fluctuation at two points is smaller when the distance is longer. (Exception : Thermoelastic noise at low temperature. Correlation is almost perfect because of extremely high thermal conductivity) 26

6. Flatter beams M. Tacca: High order mode beams M. Granata et al. , Physical Review Letters 105(2010)231102. L. Carbone et al. , Physical Review Letters 110(2013)251101. 27

7. Coatings 20 years ago … Nobody cared coating thermal noise because it is 10000 times thinner than mirror thickness. However, Levin’s breakthrough paper pointed out it could be an issue ! Y. Levin, Physical Review D 57(1998)659. Analytical and numerical calculations and measurement show it should be an issue ! G. M. Harry et al. , Classical and Quantum Gravity 19(2002)897. N. Nakagawa et al. , Physical Review D 65(2002)102001. K. Yamamoto et al. , Physics Letters A 305(2002)18. 28

7. Coatings First observation of thermal noise by coating K. Numata et al. , Physical Review Letters 91 (2003) 260602 29

7. Coatings The book about coating thermal noise was published on 2012 ! Cambridge University Press 30

7. Coatings Progress in the last 20 years Many people investigated conventional dielectric multilayer coating (IBS). The loss angle is on the same order of magnitude (10 -4) even if coating is cooled. Crystalline coating has much smaller loss (10 -5), but open questions for large mirror. G. Cagnoli: Review talk on the status of the art and known limitations 31

8. Posters Three posters They also give short introduction oral talk in our session. Peter Murray : Low-temperature mechanical dissipation of thermally evaporated indium film (Mariëlle van Veggel or Iain Matin give presentation, Tuesday morning) Mariëlle van Veggel : Current status of the bonding research for silicon and sapphire (cryogenic) suspensions(Tuesday afternoon) Jessica Steinlechner : Optimization of Si-based Highly. Reflective Mirror Coatings for 1550 nm(Wednesday afternoon) 32

9. Summary Thermal noise workshop (Thermal Noise and Materials, Coatings, Optics, Cryogenics) on Tueday and Wednesday. 7 sessions (Short term upgrades, Thermal noise modelling (coating, non thermal equilibrium), Cryogenics, Flatter beams, Coatings) Half of our session is for discussion. We need your help for vivid discussion ! 3 posters (They give short introduction oral talk) 33

Thank you for your attention and let us enjoy discussion ! 34

8. Posters Mariëlle van Veggel : Current status of the bonding research for silicon and sapphire (cryogenic) suspensions Peter Murray : Low-temperature mechanical dissipation of thermally evaporated indium film Stuart Reid : DLC coated silicon cantilever blade springs for improved vertical suspension thermal noise performance for future GW detectors? Jessica Steinlechner : Optimization of Si-based Highly. Reflective Mirror Coatings for 1550 nm Julius Komma (Jena) Electronical Absorption of Silicon at Cryogenic Temperatures 35

3. Thermal noise modelling 36

5. Cryogenics and Materials Sapphire bulk for KAGRA About 220 mm diameter, 150 mm thickness https: //www. tum. de/en/abouttum/news/pressreleases/short/article/31391/ R. Nawrodt : Materials for suspensions and test masses in a cryogenic detector 37