Fabrice, Hugo,
A GS13 huddle test was performed in order to pursue the investigation of the gain difference observed on the TFs measured on HAM-ISI Unit#2 (alog #2308)
Three horizontal GS13s were tested on the “bench”
- Pod #94, Production
Initially installed on this unit. Gain is half too small. One of its two op-amp could be malfunctioning.
- Pod #71, Production Spare
Response lower by a factor of 100 to 10000 below 20Hz. The seismic mass can be felt/heard when tilting the instrument, hence it is not stuck. The instrument will be opened at LHO for inspection. It will have to go back to LLO to pass the leak-checking-test before being installed on a Unit.
- Pod #66: Test instrument
Locked test-mass got unlocked after manipulation. Acceptable power-spectrum. Not vacuum-compatible.
Conclusion:
Production GS13s are malfunctioning. The Test GS13 Pod #66 will be used temporarily for this testing phase of HAM-ISI Unit #2 testing. It will be removed before storage of the unit. Later on, a production GS13 will be installed for the side-chamber testing.
Test-GS13 Pod #66 was installed on HAM-ISI Unit #2, as H3. GS13 doors were closed. Phase 1 of HAM-ISI Unit #2 testing is in progress. Transfer functions are being recorded overnight.