Vent plan for July 2011

Overview

Major tasks for vent:

• Optimize cavity lengths: PRC, SRC, MICH, arms, etc.
  • This will involve moving at least (but hopefully at most) one ITM to adjust the MICH Schnupp asymmetry. We will then need to move the ETMs and P/SRMs accordingly to set the proper arm/recycling cavity lengths.

  • See wiki page on cavity lengths: IFO Modeling/RC lengths

• Extract Y green beam from vacuum
  • The green locking beam from the Y-arm is currently not making it out of the vacuum. We need to fix this by adjusting the green periscope. We will then need to adjust the X-arm green beam as well.
• Align pick-off port: POX, POY, POP
  • Make sure all of these beams are cleaning making it out of the vacuum on to the PO PDs.
• Align IPANG QPD (eliminate clipping)
  • Cleanly position the IPANG beam on the IPANG QPD.
• Replace green steering mirrors PR3/SR3 with optics with better coatings.

Maybe:

• Adjust OSEM rotation to minimize unwanted couplings.
• Install green light beam dumps.
• Replace PR2 for better green transmission.

Preparation

We need precise measurements of the cavity lengths in order to determine where exactly we need to move the test masses.

• [http://nodus.ligo.caltech.edu:8080/40m/4821 Michelson Schnupp asymmetry]

• Power recycling cavity (PRCL)
• Signal recycling cavity (SRCL)

Measurements:

MICH = lx - ly = 3.62 cm
PRCL = (lx+ly)/2 + lsr = ?
SRCL = (lx+ly)/2 + lpr = ?

Questions:

• What are all of the current cavity lengths, and what should they be?
• Which ITM do we need to move, and by how much?
• Where do we need to move ETMX/Y, P/SRM?
• Do we need to move the BS?
• How exactly do we move the suspended optics? How will we know they're in the right place?
• Do we need better optics for the green beams? Are the AR coatings of the current ones ok?
• Where do we need to install beam dumps?
• Do we need more black glass or polished stainless beam dumps?
• How do we test the OSEM positioning?

Vent

door removal

1. BSC north
2. ITMYC north
3. ITMXC west
4. ETMYC north
5. ETMXC west

Procedure

This is a preliminary procedure plan:

CR:

1. Lock Y-arm green
2. Reduce power to mode cleaner (appropriate level for in-air MC locking)

IOOC north access:

1. Adjust green periscope to extract Y green transmission

CR:

1. Lock X green

IOOC north access:

1. Align X green trans through green periscope

BSC north access:

1. Adjust IPANG

CR:

1. Misalign PRM

ITMYC north access:

1. Move ITMY into position

ITMXC west access:

1. Move ITMX into position

CR:

1. Realign PRM

ETMYC north access:

1. Move ETMY for YARM

ETMXC west access:

1. Move ETMX for XARM

BSC north access:

1. Move PRM for PRC

BSC north access:

1. Move SRM for SRC
2. Align pick-offs

Equipment list