Arnaud, Saravanan

Hanford (H1) HAM4-5 ISI contributions to suspoint length (DOF)

This alog is the extension of the study we have carried out on L1 data for "HAM4-5 ISI contributions to length suspoint motion" (46407 & 46470). We could conclude for L1 suspensions that, below (300mHz) suspoint length motion is limited by horizontal motion of the platform ('Y' DOF) during day and night times. But above that frequency, motion is limited by 'Rx' (tilt) motion during night times, and limited by 'Y' (horizontal motion) during day times.

We ended with, in order to improve the suspoint length motion >1Hz, we would need to both improve the Y and Rx motion of the platform.

Similar study on H1 data shows that at low frequencies (<300mHz) suspoint length  motion is limited by horizontal motion in 'Y' DOF (as L1) but above that the motion is only limited by 'Rx' (tilt) (day & night). Only for SR2 we have seen some contribution of  'Rz' from 3-5Hz  from HAM4. Refer attached pdf1, pdf2 and pdf3 for SR2, SR3 & SRM suspensions. 

For this study we have considered data during low & high anthropogenic noise (30th May 1:00 A.M PT & 1st June 1:00 P.M PT) and also considered transformation matrices (cart2eul) from H1-HAM-ISI's (HAM4 & HAM5). Time epochs for this data show considerable variations in seismic bands (summary pages quiet & noisy) during day & night times, hence used for analysis.