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Fri Jan 2 17:20:44 2009
Computer Scripts / Programs
I have made a '40m' directory in the iscmodeling CVS tree which allows one to run a 40m version of GWINC.
As does the previous one, it takes the default advLIGO config file and modifies some of the struct parameters
to make it appropriate for the 40m.
To make it run, I have added susp1.m to the GWINC directory. This calculates suspension thermal noise using
that was later extended to
mirrors by Y. Levin. This is also the code used in the LIGO Noise Budget at the sites.
The previous code was giving a much larger value for thermal noise (probably because I didn't understand how
to use it right). It was based on a SURF report from '99.
Since we will have a mixture of MOSs and SOSs in the arms, I have just used SOSs in the model. So the suspension
thermal noise is overestimated by ~sqrt(2) (and realistically its uncertain by a much larger factor).
Since the new code now uses GWINC, the mirror and coating thermal noise are now more correct and use the
coherent therm-optic noise picture.
The 2 page PDF file shows the noise for 0 deg and 90 deg tuning of the SRC.
Although it looks like, from this plot, that we could measure coating thermal noise at the 40m, in reality we would have
to fix all of the technical noise sources first. Just the coil driver noise is probably at the level of 3 x 10^-17 m/rHz
at 100 Hz.