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D isplacement of BRT

D isplacement of BRT. Junko Katayama. TMS. ETM. BRT. GPT. QPD. What I did. Lateral and angular motion of BRT cause the noise on QPDs. I computed those BRT motion noise and shot noise for both SOFT and HARD mode in two cases ; TMS table fixed on the ground TMS suspended by pendulum.

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D isplacement of BRT

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  1. Displacement of BRT Junko Katayama

  2. TMS ETM BRT GPT QPD

  3. What I did Lateral and angular motion of BRT cause the noise on QPDs. I computed those BRT motion noise and shot noise for both SOFT and HARD mode in two cases ; • TMS table fixed on the ground • TMS suspended by pendulum

  4. Angular motion There are two types of angular motion. • Surface wave on the ground (v=5000m/s) Θ = 2πf * x_seis / v • Table motion (simulation data from ATC) y1 Z-rotation X,Y-rotation x1 s1 = x1 s2 = -1/2*x2 + √3/2*y2 s3 = -1/2*x3 - √3/2*y3 Rθz =(s1+s2+s3)/3 z1 y3 y2 z3 z2 x3 x2 Rθxy = (((z2+z3)/2)*2-z1)

  5. Angular motioncomparing surface wave & table move ↑dominant

  6. Table motion is quite smaller than surface wave → consider only surface wave as the angular motion of BRT From the next slide, I computed the noise contribution to h for each SOFT and HARD mode. There are two lines with each noise ; Ex) shot1 : shot noise on QPD1 shot2 : shot noise on QPD2

  7. SOFT modefixed on the ground

  8. HARDmodefixed on the ground

  9. Transfer Function z1 z2 d=1m , M=200kg d X = 1/(1-(ω/ω0)2+iω/Qω0)*x_seis Θ = dk(1％*x_seis)/(-Iw2+2d2k) z2-z1=1％*x_seis I=M(2d)2/12 Mg ↑ Suspended by 2 wires

  10. SOFT modesuspended

  11. HARDmodesuspended

  12. Conclusion • rotation of TMS table is not dominant → surface wave is dominant • we can get HARD signal with TMS suspended …cannot get SOFT because of shot noise

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