LIGO Document E1200103-v3
- This document presents the tests performed to characterize and validate the “HAM-ISI LLO Unit #4”. This unit was the 4th unit assembled for aLIGO at LLO. This unit was assembled in June and July 2011.
This was the third unit pulled out from storage for installation at Livingston in January 2012, to be installed in HAM 4 chamber. Horizontal seismometers, springs tuned mass dampers, and final cables were installed. Also, the Capacitive Position Sensors cables were shielded.
This document is thought as the follow-up of the previous test document, written after assembly. Only modifications and basic functionalities were tested at this time.
There are 4 distinctive parts:
• Part I: side chamber testing results
Intro to Part I
Side chamber testing was conducted in the LLO LVEA with actual electronics and field cables from May 9th until May 23rd 2012. Temporary extensions to those cables were used to reach the test stand located further away from the electronics than the HAM chamber is.
Steps 1 and 2 capture data from testing done previously, whereas all the following steps were done (or waived) during that side-chamber testing period.
Conclusion to Part I
Only a few minor issues were found during testing of this ISI:
- Slightly different actuator slope on H3 (in comparison to the other horizontal actuators)
- Slightly different response of the H1 GS-13 (in comparison to H1 and H2) between 0.8 and 1.1 Hz. This appears to be explained by the different sensors responses.
A number of mechanical tests (and adjustments) were waived at the time of side-chamber testing, leaving this for in-chamber initial testing:
- Level of the optical table
- Spring flatness measurements
- Horizontal actuator gaps
Conclusion of in -chamber testing
Most issues found while side-testing were solved during this phase of the testing. Very few issues were found during the testing of this unit. The known issues are summed up here:
- The Linearity test gives a slightly different slope on the H2 actuator (1.5% from average for a 1% criteria)
- We have a slight offset of 2 CPS: H1 and V3.
Issues unchanged since the Phase I testing:
- sensor gaps not recorded on the jig
- Vertical spring constant: one spring appears to have a much lower constant than the others (-8.91% than the average of the 3).
- Added tilted table in chamber plot+ corrected a few glitches
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