Project: Charecterization of MMT3’s motion

Name: Raghuveer Dodda (“Raghu”)

Mentor: Dr. Sanichiro Yoshida

• Location of MMT3

• Degrees of freedom

• Resonance Frequencies

• Power Spectrum of MMT3 – a peak can be observed around 1.5Hz. MMT3 does not have any resonances around this frequency

• Coherence between MMT3 motion and ASC_Q beam – a peak can be observed at 1.5Hz

• The LVEA ground noise shows some peaks between 1.4 – 1.6 Hz. This is also the region where the HAM table has its resonances ( as measured at Hanford).

• HAM stack modes U-U transfer at 1.5Hz and HAM stack V-V transfer is at 1.6Hz (LIGO T-000020W)

• Peaks in the same region are seen in HAM1 table accelerometer readings as well, suggesting HAM table’s translation motion in U,V directions.

• This motion will also produce an yaw to HAM table. Could this yaw be causing an motion of the mirror, particularly, the yaw motion ?

• See how the HAM table motion affects the motion of the mirror – using e2e. I made the required box files to see the motion of MMT3.

• Get an estimate of the table motion since there can be no direct measurement of the table motion. This was done by Dr. Yoshida using the readings from the OSEMs behind various optics on the HAM table.

• The idea was that if we could reproduce the motion of MMT3 using the e2e model and if it agrees with the actual measurements of MMT3 motion, the model is good and thus it can be said that MMT3 has been characterized.

HAM table motion

HAM table motion

table motion power spectrum

0.00E+00

1.00E-06

2.00E-06

3.00E-06

4.00E-06

5.00E-06

6.00E-06

1 1.2 1.4 1.6 1.8 2

f (Hz)

mag

nit

ud

e

pw sp avg U

pw sp avg V

pw sp theta (hamyaw)

Free hanging mirror model

• iput = motion of HAM1 at the location of MMT3 as calculated by the OSEM-method

• oput = x,y,z,xtheta,ytheta,ztheta of MMT3 (as a function of time)

• The PS of the output reveals peaks at:

MMT3 Yaw: 0.5 Hz (MMT3 yaw peaks) , 1.4 -1.6 (HAM1 peaks)

[ m(mmt3,abs_ref) = m(grd, abs_ref) + m(ham1,grd) + m(mmt3,ham1). Since, there is no m(grd,abs_ref) in the iput, we should not see any m(grd,abs_ref) peaks in oput. ]

Results of sus3d.box – the free hanging mirror

MMT3 Yaw HAM1 Yaw

Free hanging mirror model (with ground motion)

• iput = The ground noise for HAM1 at Hanford as calculated by e2e

• oput = The Yaw of MMT3, the Yaw,x-disp,y-disp of HAM1 (as a function of time)

• The PS of the output reveals peaks at:

MMT3 Yaw: MMT3 peaks, HAM1 peaks, ground motion peaks

HAM1 Yaw: HAM1 peaks, ground motion peaks

[ m(mmt3,abs_ref) = m(grd,abs_ref) + m(ham1,grd) +m(mmt3,ham1) ]

Results of han-sus3d.box – the free hanging mirror

MMT3 Yaw

HAM1 Yaw

Mirror with servo mechanism

• iput = The HAM1 motion at the location of MMT3 as calculated by using the OSEMs

• oput = x,y,z,xtheta,ytheta,ztheta of MMT3 (as a function of time)

• The PS of the output reveals peaks at:

MMT3 Yaw: MMT3 peaks (exist if gain is low; absent if again is high), HAM1 peaks

• The transfer function should have a low value at Yaw resonance and higher value at stack resonance.

Future Work

• Finish the servo box and test all the boxes extensively (and debug them if necessary) .

• Make ground noise measurements so that this can be given to the e2e model.

• Work will be continued at SLU with Dr. Yoshida.