Mistake in suspension thermal noise calculation
I think there's a mistake in the suspension thermal noise calculation. Right now we break the calculation up into an upper joint and a lower joint for each stage. We store the horizontal and vertical susceptibilities (hForce
and vForce
) as arrays where the indices of the upper joints are even and the indices of the lower joints odd. We add these correctly when calculating the total noise here:
https://git.ligo.org/gwinc/pygwinc/-/blob/master/gwinc/noise/suspensionthermal.py#L57
However I think we have the upper and lower joints switched when we calculate hForce
and vForce
here:
https://git.ligo.org/gwinc/pygwinc/-/blob/master/gwinc/suspension.py#L576
I think this should be
if m % 2:
lossy_region_lower[n] = 1
else:
lossy_region_upper[n] = 1
so that the indices of the lossy upper joints are even and those of the lossy lower joints are odd.