Alexa, Nic, Evan, Dan, Sheila

Tonight we went back to trying to get ALS DIFF working well.  We aren't sure what the problem is. 

First Nic checked that the gain of the 2 ESDs were the same.  The old X gain in L3 LOCK L was 0.2, the new one is 1.12 The old Y gain was 0.7 the new one is 0.384.  We also checked the crossover by using the green control signal. 

Attached are some plots, based on the suspension model that Jeff used to design the DIFF loop, and filters downloaded from foton. This is using none of the boosts for DIFF, which is how we have been running the last few nights without being able to use the ESD.  The two plots on the left are the cross overs for our loop, and the open loop.  We can use these plots to compare what we have now to what Jeff originally designed, (G1400146-v2)  We also copied the livingston filters, see alog (12590), their crossover is the third plot while their open loop (we added a scaling factor to get the right ugf) is the last plot on the right. 

Btoh ESDs are driving, but we seem unable to use them in the loop.