Vibration measurement in the cryogenic interferometric gravitational wave detector (CLIO interferometer)

Transcription

1 Vibration measurement in the cryogenic interferometric gravitational wave detector (CLIO interferometer) ICRR Univ. of Tokyo, Dept. of geophysics Kyoto University A, KEK B, Dept. of advanced materials science Univ. of Tokyo C, Sumitomo Heavy Industries Ltd. D K. Yamamoto, T. Uchiyama, S. Miyoki, M. Ohashi, K. Kuroda, H. Hayakawa A, T. Tomaru B, N. Sato B, T. Suzuki B, T. Haruyama B, A. Yamamoto B, T. Shintomi B, S. Moriwaki C, Y. Ikushima D, T. Koyama D, R. Li D 2006 March 28 The meeting of Physical Society of University

2 0. Abstract Measurement of the vibration at the top of suspension and inner shield of CLIO interferometer

3 Contents 1. Introduction 2. Outline of experiment 3. Results 4. Future works 5. Summary

4 1. Introduction LCGT and CLIO : future and current Japanese project to construct the interferometric gravitational wave detector (1) Cryogenic interferometer (20 K) : reduction of thermal noise (2) Kamioka mine : small seismic noise Cryocooler Vibration Measurement of vibration with operating cryocooler is necessary.

5 Schematic view of cryogenic apparatus (1)Top of suspension (300 K) Vacuum chamber (300 K) Outer shield (100 K) Inner shield (8 K) Intermediate mass (10 K) Cryocooler (4 K) Heat link (2)Shield (8 K) Measurement point (1)Top of suspension (300 K, vacuum) (2)Shield(8K, vacuum) Mirror (20 K) CLIO cryostat in Kamioka mine

6 2. Outline of experiment 2-1. Location Kamioka mine (LCGT,CLIO site) 220km west from Tokyo Kamioka 220km Tokyo (TAMA)

7 2-2. Cryostat of CLIO interferometer (end) Gifford-McMahon refrigerator (removal) Mirror Top of suspension (room temperature, vacuum, 1.9 m from floor, support of four poles) Inner shield (low temperature, vacuum, 0.6 m from floor, support of G10 rods) Pulse tube cryocooler : extremely small vibration 4K Pulse tube cryocooler 80K Pulse tube cryocooler Shield (developed by KEK and Sumitomo Heavy Industries Ltd.) Class. Quantum Grav. 21(2004)S1005. Compressor Beam splitter (100m ahead) by T. Uchiyama

8 Top roof Door Cryostat of CLIO interferometer

9 Top of suspension

10 Top roof Door Cryostat of CLIO interferometer

11 Inner shield Duct Bottom of shield

12 2-3. Accelerometer Laser source (diode) 635 nm Reference Mirror(fixed) Steering mirror Beam Splitter (fixed) Oscillator Vacuum chamber (Laser source and photo detectors are in vacuum chamber. Sound does not affect accelerometer directly.) Only room temperature 5 mw Photo Detector Photo Detector Output Observation band < 400 Hz (horizontal) < 250 Hz (vertical) + Differential amp Filter

13 Accelerometer Laser source Beam Splitter Reference mirror Oscillator 145 mm Coil Photo detectors

14 3. Results 3-1. Top of suspension (Horizontal:optical axis) < 200 Hz Displacement [m/hz 1/2 ] Cryocoolers and pump do not increase vibration. > 200 Hz Cryocoolers and pump increase vibration / f 1/2 [m/hz ] Top of suspension(horizontal) Pulse,pump on (2005/3/10:first) Pump on (2005/3/10:second) Off (2005/2/3:second) Kashiwa (2004/8/6:second) Vertical : similar Frequency [Hz]

15 3-2. Inner shield (Horizontal:optical axis) Cryocoolers and pumps do not increase vibration. G10 rods > 200 Hz vibration isolation Displacement [m/hz 1/2 ] / f 1/2 [m/hz ] Frequency [Hz] Shield (Horizontal) Pulse on (2005/10/6) Pump on (2005/10/5) Off (2005/10/4) Kashiwa (2004/8/6:second)

16 3-3. Inner shield (Vertical) / f 2 1/2 [m/hz ] Vacuum pumps increase vibration. Cryocoolers : peaks > 200 Hz G10 rods vibration isolation Displacement [m/hz 1/2 ] Shield (Vertical) Pulse on (2005/10/13:second) Pump on (2005/10/13:first) Off (2005/10/12) Kashiwa (2004/8/16:first) Frequency [Hz]

17 3-4. Comparison with floor (Horizontal:Optical axis) Floor /2 10 / f [m/hz ] Suspension top peak Inner shield : 30 Hz 10 Hz Hz 100 times Displacement [m/hz 1/2 ] / f 1/2 [m/hz ] Frequency [Hz] Horizontal motion Top of suspension (2005/2/3:second) Inner shield (2005/10/4:first) Floor (RION) (Perpendicular end 2005/5/10) Kashiwa (2004/8/6:second)

18 3-5. Comparison with floor (Vertical) Floor /2 10 / f [m/hz ] Suspension top peak Inner shield : 30 Hz, 40 Hz 10 Hz Hz 10 times Displacement [m/hz 1/2 ] / f 1/2 [m/hz ] Frequency [Hz] Vertical motion Top of suspension (2005/6/8:first) Inner shield (2005/10/12:first) Floor (RION) (Inline end 2005/5/11) Kashiwa (2004/8/16:first)

19 3-6. Sensitivity of CLIO interferometer External vibration does not limit sensitivity above 40 Hz at 300 K. above 60 Hz at 20 K. < 40 Hz Suspension top dominant Displacement [m/hz 1/2 ] Noise budget of CLIO From top of suspension From inner shield Shot noise Radiation pressure noise Standard quantum limit Thermal noise (mirror) Thermal noise (mirror at 300K) by T. Uchiyama Frequency [Hz]

20 4. Future works (For LCGT) (1) Cryocooler : no serious problem (2) Vacuum pump : some problems (inner shield, vertical motion) (Dry pump) < (Rotary and turbo pump) Connection with cryostat (3) Suspension top : peak (30 Hz) SAS (4) Inner shield : large vibration (10 Hz Hz) SPI Study of inner shield vibration

21 5. Summary (1) Measurement of the vibration at top of suspension and inner shield of CLIO interferometer (2) Cryocooler : no serious problem Vacuum pump : some problems (inner shield, vertical motion) (3) Suspension top : peak (30 Hz) Inner shield : large vibration (10 Hz Hz : times) (4) CLIO interferometer sensitivity : External vibration does not limit sensitivity above 40 Hz at 300 K. above 60 Hz at 20 K. (5) Future works for LCGT : Vacuum pump Inner shield vibration

22 KamLAND (KAMIOKANDE) Super KAMIOKANDE Dark Matter Detector Perpendicular Exit Superconducting gravimeter (LISM[20m]) Inline Location of experiment CLIO[100m] CLIO Location in Kamioka mine

23 Dry pump

24 Dry pump

25 Duct of CLIO interferometer Cryostat Turbo pump To rotary pump

26 4K Pulse tube refrigerator

27 80K Pulse tube refrigerator

28 Compressor

29 thermal switch Gifford-McMahon refrigerator

30 SHI SRP-052A 2 Cryostat 80K 4K

31 2. Outline of Experiment 2-1. Outline of accelerometer (i) Free mass : reference (ii) Sensor : displacement between free mass and shield Sensor Shield Free mass Force (iii) Actuator : feedback Actuator Mass follows shield. Acceleration Acceleration of shield is derived from feedback signal. Horizontal and vertical vibration measurement Goal sensitivity : Seismic motion in Kamioka mine

32 2-2. Components of accelerometer (i) Free mass : Mechanical harmonic oscillator Material : Phosphor bronze Resonant frequency : 20 Hz 20 mm * 20 mm *20 mm 20 mm length 0.3 mm thickness 1 mm width (ii) Sensor : Michelson interferometer (Calibration) (iii) Actuator : Coil-magnet actuator (Operation at low temperature)

33 Vertical oscillator Coil Oscillator BS Reference mirror Steering mirror holder

34 Accelerometer Beam splitter of CLIO Laser source Interferometer Top of suspension

35 Displacement [m/hz 1/2 ] Interferometer noise Horizontal, Top of suspension pulse, pump off interferometer noise (2005/3/16:third) seismic motion (2005/2/3:second) Frequency [Hz]

36 Displacement [m/hz 1/2 ] Interferometer noise Top of suspension Vertical, off interferometer noise (2005/7/7:second) seismic motion (off:2005/6/8:first) Frequency [Hz]

37 Noise of interferometer (off) Top of suspension vertical(2005/7/7:second) horizontal(2005/3/16:third) Displacement [m/hz 1/2 ] Frequency [Hz]

38 Displacement [m/hz 1/2 ] Top of suspension Horizontal pulse,pump on (2005/3/10:first) pump on (2005/3/10:second) pulse,pump off (2005/2/3:second) Frequency [Hz]

39 Displacement [m/hz 1/2 ] Suspension top (Vertical) Pulse on (2005/6/14:second) Pump on (2005/6/8:third) Off (2005/6/8:first) Frequency [Hz]

40 3-2. Horizontal motion (optical axis:>100hz) >400Hz Upper limit Refrigerator increases vibration 100 times (1 khz). Seismic motion [m/hz 1/2 ] Top of suspension Horizontal motion pulse,pump on (2005/3/10:first) pulse,pump off (2005/2/3:second) fixed mirror (on) (2005/3/16:first) fixed mirror (off) (2005/3/16:third) Frequency [Hz]

41 Displacement [m/hz 1/2 ] Suspension top (Vertical) Pulse on (2005/6/14:second) Off (2005/6/8:first) fixed mirror(pulse on) (2005/7/8:first) fixed mirror(off) (2005/7/7:second) Frequency [Hz]

42 3-2. Vertical motion (< 1 khz) floor level (1 Hz-70 Hz) /2 10 / f [m/hz ] < 200 Hz Cryocoolers do not increase vibration seriously. Displacement [m/hz 1/2 ] / f 1/2 [m/hz ] Vertical motion pulse on (2005/6/14:second) pulse,pump off (2005/6/8:first) pump on (2005/6/8:third) Kashiwa (2004/8/16:first) Frequency [Hz]

43 3-3. Vertical motion (< 1 khz) floor level (1 Hz-100 Hz) /f [m/hz 1/2] < 200 Hz Refrigerator does not increase vibration seriously. Seismic motion [m/hz 1/2 ] /f [m/hz 1/2] Vertical motion pulse,pump on (2005/3/18:second) pulse,pump off (2005/3/18:first) CLIK end (2004/8/16:first) Frequency [Hz]

44 Cryostat RION

45 3-5.Gifford-McMahon refrigerator (Horizontal motion) GM refrigerator inceases vibration. 30 Hz-400 Hz Kashiwa level! Seismic motion [m/hz 1/2 ] GM refrigerator (Horizontal motion) GM on (2005/1/21:second) pulse,pump on (2005/3/10:first) CLIK end (2004/8/6:second) Frequency [Hz]

46 3-2. Operation at room temperature (2) (Cryostat vs optical table) Hz : about same 30 Hz -100 Hz : larger motion in cryostat 100 Hz - : better sound isolation in cryostat Seismic motion [m/hz 1/2 ] Seismic motion CLIK (Kashiwa) end pump off (2004/3/13) optical table (2004/2/21) Frequency [Hz]

47 3. Results 3-1. Operation at room temperature Comparison with RION (i) Horizontal motion Seismic motion [m/hz 1/2 ] Horizontal seismic motion in cryostat (2004/8/5:in air:kashiwa) Interferometer RION Consistent (0.2 Hz Hz) Frequency [Hz]

48 (ii) Vertical motion Seismic motion [m/hz 1/2 ] Vertical seismic motion in cryostat (2004/8/14:in air:kashiwa) Interferometer RION Consistent (0.3 Hz Hz) Frequency [Hz]

49 Displacement [m/hz 1/2 ] Shield of CLIO cryostat Horizontal,perpendicular end pump,pt off Interferometer (2005/11/30) RION(2005/11/30) Frequency [Hz]

50 Displacement [m/hz 1/2 ] Shield of CLIO cryostat 2005/10/4(pump,PT off) 2005/10/4(50m pump on) Frequency [Hz]

51 50 m pump Duct Turbo pump Rotary pump