Among the majors issued discussed in the kickoff meeting on 22nd were (1) the implementation of more realistic servos in the simulation so that it can be used to study the servo characteristics and noise propagation. and (2) the implementation of ASC.
After the kickoff meeting, Luca Matone volunteered to work on the LSC part and Andrea Vicere on the ASC part. To get this activity start rolling, there was a meeting held on May 30th, having Nergis as the detector expert/advisor. People attended were Luca, Andrea, Matt, Nergis, Hiro and Biplab.
The following are the summary of the discussions.
(1) Time domain simulation of the servo noise will be necessary because of the complexity of the system, even though the lowest order estimation can be done (semi-)analytically in the frequency domain.
(2) There are many uncertainties of noise sources, so the model will use the measured spectrum as the noise source at an appropriate point and refine it when things change (reduced by hardware refinement, understanding the physics origin, etc).
(3) The simplest model of LSC is
detector -> mixing -> whitening -> AtoD ->
[ whatever the digiatl system ] -> DtoA -> de-whitening -> actuation
At each stage, noise could be added which is generated using a measured noise.
(4) the triangular mode cleaner simulation will be necessary to simulation the amplitude noise induced by the length fluctuation.
(5) First will be the implementation of the simplest LSC model ( (3) above ) with a very simplified (with a parameterized frequency noise) laser coming into COC.
(6) Luca will go to Hanford to gather necessary information with the help of Nergis.
(7) Part of the ASC model will be a copy of the same building blocks developed for LSC, although N time more circuit lines.
(8) ASC is a moving target now, there are some hard to understand. May be simulation can help to understand them.
(9) Andrea will first understand the ASC design. The first implementation can adopt the simple method used in the current LSC model - no digitization etc, and the complex structure can be embedded later on top of it.