¶ Hydraulic External Pre-Isolation
Also known as HEPI, this is the stage of seismic isolation external to the vacuum, between ground and the ISI (the active isolation internal to the chamber).The Hydraulic External Pre-Isolator (HEPI) is the Laser Interferometer Gravitational Wave Observatory's first 6 degrees of freedom active seismic isolation system.
Prior to LIGO's 5th science run, implementation was completed at the LIGO Livingston Observatory (LLO), successfully reducing the disturbance seen by LLO's suspended optics by a factor of a few to tens in the two most prominent seismic disturbance bands, microseism (0.1-0.3Hz) and anthropogenic (1-3Hz). The improved seismic isolation directly contributed to LLO's 66.7% duty cycle and LIGO's 53% triple coincident duty cycle. In this paper, we describe the design, control scheme, and isolation performance of HEPI at LLO.
¶ Channel Name Breakdown:
| Name | Description |
|---|---|
| Channels | |
| HPI | HEPI, Hydraulic External Pre-Isolation |
¶ Sources
Hydraulic external pre-isolator system for LIGO - IOPscience