LVEA Infrasound Detector
Here you're in the very center of the LIGO Hanford (LHO) Laser and Vacuum Equipment Area (LVEA). Spin the panorama so that you see the view that's 180 degrees opposite from the yellow-railed steel stairs. A tall orange ladder is visible on the left and a black rack containing electronics sits just right of center. The large vacuum chamber directly in the center of this view holds the H1 beam splitter. The chambers to the right and left hold the inner cavity mirrors that reflect the light back and forth along LIGO's four-kilometer arms.
As the panorama rotates, viewers can see that the floor space is enclosed by the beam tube on all sides and can be accessed only via the stairway. LIGO places a number of environmental sensors in this area; several of the floor-mounted sensors such as a seismometer and a tilt meter sit behind the metal rail that's underneath the stairs. LIGO has added a new sensor to the site's array, an infrasound detector. Some of the electronics controls for this device are visible in the photo. LIGO has always deployed highly sensitive microphones in the LVEA to monitor acoustic noise near the vacuum chambers. The infrasound devices can detect vibrations of the air at frequencies lower than the microphones can sense (below 20 Hz), adding an important capability to LIGO's environmental monitoring program.