Date: May 30th, 2001

Attendees: Malik Rakhmanov( U. Florida), David Shoemaker(MIT), Rick Savage, Mike Landry, Bill Butler, Mark Barton (LHO), Hiro, Matt, Nergis, Alain, Michel, Andrea, Biplab(Caltech)

Alain Weinstein talked about simulation activities being pursued by him and his visiting student, Michel Guillaume (his transparencies.).

The final objective of their work is to arrive at a good control system for the advanced LIGO and, he insists, that it is not a simulation of just the 40 meter IFO. However, since the study of advanced LIGO needs development of a dual recycling summation cavity module in e2e (..and the e2e team's limited manpower is mostly invested in LIGO I activities), they have chosen to work with a 40 meter model which, due to its small arm-to-recycling length ratio, can be simulated by primitive mirrors and propagators.

Alain opines that most probably the difference in length between model and full-scale LIGO would not affect the conclusions to-be-derived about the control system of 4Km LIGO from this 40m model. Nergis and Matt differs with him on this point. They say that unless the time scale is right, the conclusions derived for lock acquisition would be unrealistic.

The discussion among Alain, Matt, Hiro and Biplab concludes that there is no need to pursue the use of power-recycled summation cavity module with a primitive mirror for signal recycling. We do not gain much and at this point we are not sure if such a combination works well.

Malik talked about his calculations on dual recycling and the corresponding Matlab code. He has not yet introduced the first derivative in the approximation for the mirror motion in his analytical expressions. He has updated his technical note on these calculations.

Any comments? write to bbhawal@ligo.caltech.edu