hugo.paris@LIGO.ORG - posted 18:09, Tuesday 23 July 2013 - last comment - 18:14, Tuesday 23 July 2013(7189)
HAM2 HAM3 HEPI Release - IMC Alignment Reestablished
HAM2 and HAM3 HEPI were released today.
Raw IPS readouts were recorded prior to release. The following offests were set in the actuation path to reestablish alignment, based on the IPS readouts:
| OFFSETS (cnt) | ||
| HAM2 | HAM3 | |
| H1 | 370 | 900 |
| H2 | 800 | 200 |
| H3 | -600 | 350 |
| H4 | -400 | -650 |
| V1 | 450 | 300 |
| V2 | 460 | -650 |
| V3 | 1050 | 200 |
| V4 | 900 | 1250 |
IPS readouts were recorded after reestablishing alignment:
| NEW READOUTS (cnt) | ||
| HAM2 | HAM3 | |
| H1 | 1438.7 | 6664 |
| H2 | 957.61 | -4089.2 |
| H3 | 2089.2 | 9159.3 |
| H4 | -1238.1 | -2252.5 |
| V1 | -2796.8 | 2709.1 |
| V2 | -608.92 | -6394.7 |
| V3 | 1029.5 | 2257 |
| V4 | -2862.8 | -9434.1 |
The Before/After difference in IPS readout is shown below:
| BEFORE/AFTER DIFFERENCE (cnt) | ||
| HAM2 | HAM3 | |
| H1 | 107.6 | 146.6 |
| H2 | 0.11 | 588.7 |
| H3 | 68.2 | 169.1 |
| H4 | 65.5 | 104.3 |
| V1 | 54.1 | 155.1 |
| V2 | 97.09 | 32.3 |
| V3 | 4.5 | 144.5 |
| V4 | 20.1 | 38.3 |
The remaining shift in alignment induced by unlocking HAM2 and HAM3 HEPI is less than 0.25mils (147 counts on the IPS), on each pier, after reestablishing the alignent with offsets on the actuation path.
Note: Isolation loops tripped only on HAM2-ISI. They are back ON now.
The DC part of those loops (CPS Biases) remain unchanged from prior to HEPI release, hence ensuring consistent alignment of the platforms.