1. Understanding Cabling Noise in LIGO Chihyu Chen Lafayette College Mentors: Mark Barton Norna Robertson Helpful Researcher:Calum Torrie Co-SURF:Julian Freed-Brown

2. Cabling connecting the OMC bench to the cage

3. Pendulum as a vibration isolator Single pendulum resonant at 1 Hz How would the cabling deteriorate the isolation?

4. For structural damping For velocity damping

5. Method Experimental characterization of the cabling’s damping function. -Jimmy Chen Computer modeling to apply the damping function to specific cabling-attached-to- suspension systems. -Julian Freed-Brown

6. Apparatus Two wire torsion pendulum Support structure for the pendulum Cabling Apparatus Design Goals 1. An order of magnitude variability in yaw and pitch frequency 2. Cases that can be easily modeled 3. Stiff support structure

7. Yaw frequency range: 0.14 Hz – 1.27 Hz Pitch frequency range: 0.41 Hz - 2.97Hz Varying pitch frequency Varying yaw frequency

8. 1.Clamps ensure straight connection pts. 2.Optics table helps stiffen the support structure

9. Data Collecting Equipment used: – Kaman eddy current displacement sensor – LabVIEW data logging system

10. Data Analysis Data analysis method and computer program by Mark Barton

11. Results Model predictions by Julian Freed-Brown, based on equations by Calum Torrie. frequency measuredpredicted measuredpredicted n=1 cm0.1340.13660 plate0.6560.414 n=3 cm0.40890.40981 plate1.561.458 n=5 cm0.68360.6832 plates2.142.066 n=7 cm0.9580.9563 plates2.612.559 n=9 cm1.2271.2294 plates3.012.97 Yaw mode Pitch mode

12. Results pitch mode n = 5 cm without cabling with cabling frequencyQ QQ^0.5 0 plate0.65617031.234.85.899152 1 plate1.562376262.97.930952 2 plates2.1437752.5793.89.68504 3 plates2.6146273.1420214.21267 4 plates3.0162933.4321114.52584

14. Results Future Work 1.Feed results into Julian’s Mathematica model 2.Check for agreement between the model and experiment frequency results. 3.Study the resulting transfer functions and make recommendations on cabling dressing.