With Fabian, Enzo and Hirata-san.

Today:

• Mark and Enzo agreed on the correct matrices for the LVDT2EUL, EUL2COIL and ACC2EUL blocks, typed them in and did a new safe.snap file. See forthcoming T1707205-v4 or attached screenshots.
• We removed the tank lid and tested the LVDT2EUL matrix by gently pressing on the IP in the L, V and Y directions successively while monitoring the diagonalized signals.
• At first we got puzzling results: there was lots of high frequency noise on the Y channel. We traced this to an error in the blend filter screen: the sixth group of filter controls on the BLEND screen, which should have been for the Y component as sensed by the geophones (ACCY) was in fact a duplicate of the group for the Y component as sensed by the LVDTs (LVDTY). This meant that the ACCY filter could not be switched on or off and was stuck on. We edited the screen to correct the problem and left all the geophones disabled for now.
• We worked with Izumi-san, Nakano-san and Inoue-san to align the BS.
• FIrst we locked the IP in its nominal position, and adjusted the yaw by turning the PI yaw stepper manually until the beam went through the viewport in the gate valve on the +Y side of the BS tank.
• Then we released the IP and used manual adjustments on the FRs to recover the yaw alignment from the previous step.
• The pitch did not need any adjustment to get the beam through the first viewport.
• Enzo noticed the PI GAS LVDT was high, so we took the opportunity to adjust it lower with manual adjustments of the vertical FR.
• We replaced the tank lid and the beam did not move noticeably.
• Inoue-san monitored the beam spot at the next gate valve and asked for a slight correction clockwise (negative yaw) and up (negative pitch).
• We applied the yaw correction with remote movements of the IP FR steppers.
• We tried to apply the pitch correction with remote movements of the IM pitch pico but at first we couldn't tell if we were making progress because the IM vertical OSEMs were off-scale (too far in). We noticed that the BF GAS LVDT was about 250 µm high, so we adjusted it back to near zero with remote movements of the BF FR stepper. As hoped this brought the vertical OSEMs to mid-range and made the P (pitch) channel sensible.
• We applied about -300 µrad of pitch, and Inoue-san reported that the beam was going through the second gate valve.
• We checked to see if we could apply addtional small pitch and yaw adjustments using the IM OSEMs. (The hope was to set up an automated scanning task to run overnight and try to get the beam all the way down the tube.) The yaw was very responsive but the pitch seemed completely unresponsive. Since pitch actuation uses the vertical OSEMs, this suggests a problem with the vertical OSEM low-power coil driver box. We will check this tomorrow.