This morning, several spectra were measured to evaluate the performance of the ISI-BSC6 with different blend configurations:

• Damping (green)
• Stage 1 blend at 100mHz with T240 - Stage 2 blend at 100mHz (brown)
• Stage 1 blend at 250mHz with L4C - Stage 2 blend at 250mHz (pink)
• Stage 1 blend at 100mHz with T240 - Stage 2 blend at 250mHz (red)
• Stage 1 blend at 250mHz with T240 - Stage 2 blend at 250mHz (black)

The plot LHO_ISI_ETMY_Isolation_aLOG_ST1_Y_20120820_2.pdf shows non calibrated spectra of the T240s in the Y direction. Around 500mHz, the isolation is slightly better with the T240 in the super sensor (comparison pink and black curves - In both cases, the blend is at 250mHz).
The blend on stage 1 can be lowered at 100mHz (red and brown curves).

The plot LHO_ISI_ETMY_Isolation_aLOG_ST2_Y_20120820_2.pdf shows non calibrated spectra of the GS13s in the Y direction. The isolation impprovement seen on stage 1 are also visible on stage 2.

On both ISIs (BSC6 and BSC8), the T240s can be introduced in the super sensor (cf https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=3858).