Note from Bill Kells on October 23, 2000:
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Hi Keith,

Ahead of tomorrow's E2 meeting (I had initially intended to 
disseminate this to ~team leaders, but leave it to your discretion), 
and since you explicitly enquired about recombination running, let 
me update on that.

I spent some time in the last few weeks at LHO, looking into recomb 
locking the ifo. This was relatively easy at the 40m, but was 
certainly aided by the fact that the RM there was ~4x more 
transmissive than the LIGO 2k. We would probably lock via: RefQ->l- ; 
RefI->L+ ;and ASQ->L-. The crucial prerequisites then are to
see if the LHO 2k SM, and single arms can be locked with RefQ, and 
RefI alone. This I have established, can be done reliably. Based on 
that, I predict that recomb. locking will be straighforward. However, 
as I would have expected, I have not actually accomplished such a lock 
(simple by aligning the arms and turning the loops on with predicted 
phases). This is because, it is necessary for the l- loop to have 
its sign changed upon incipient two arm locking.

So, if it is desired to have recombination lock for the E2 it will 
be necessary to do a little work: to either write a very simple 
acquisition input matrix which just flips this sign, or to modify 
Matt Evan's full acquisition matrix so it only does this (predicted to
be possible). Then, as with anything, a few hours of run time will 
be needed to check it all out.

Bill