We performed some tests with the Vibration absorbers of stage 1 with different Vitton pads (identical contact surface and different thicknesses). Measurements done without the vibration absorbers lids.
Parameters Surface: 0.25"x0.25"
Thickness:
- 0.0625"
- 0.125"
- 0.25"
Results:
- Reduction by a factor of 6 of the 217 Hz resonance on X, Y, RX, RY using pads with a thickness of 0.125".
2 measurements (2012 01 06 no vibration absorber - 2012 01 11 6 vibration absorbers)
https://svn.ligo.caltech.edu/svn/seismic/BSC-ISI/H2/ITMY/Data/Figures/Transfer_Functions/Comparisons/
LHO_ISI_BSC8_Comparison_TF_C2C_ST1_ACT_H_to_ST1_L4C_H_20120106_vs_20120111.fig
LHO_ISI_BSC8_Comparison_TF_C2C_ST1_ACT_V_to_ST1_L4C_V_20120106_vs_20120111.fig
- With the thickest pads (0.25") the vibration absorber are less effective
- With the thinnest pads (0.0625"), performances are similar (slightly better)
Next step:
- Tests with the lids on