[Dan, Kevin, Evan, Elenna]
Here are plots of the full updated noise budget. The input jitter and frequency noise traces were rerun tonight, and the DARM reference is from a 10 minute quiet time tonight. The LSC and ASC budget injections were ran last Thursday night and have already been posted in the alog. The PUM DAC traces were ran back in January.
This budget is showing us that at low frequency, we are limited by the PUM DAC noise, and in the mid range there is some significant input jitter coupling. The input jitter is mostly in yaw, as a quick sub budget that we made shows. At high frequency we are still overestimating the frequency noise by a factor of sqrt(2) by the way we perform the measurement and calculate the contribution. That means at low frequency, the frequency noise estimate should be correct. This budget also shows quite a large amount of unknown noise.
We have so far been unable to run a bruco on the quiet time we used for the budget. We think that is because the frames haven't appeared on either the Caltech or LHO cluster.
The attached plots compare the current (pre-O4) Hanford performance against the O3 performance (see LIGO–G2100674) and the fundamental noises for 400 kW of arm power and 4.5 dB of frequency-dependent squeezing.
Among other things, we are now sensitive to about twice the comoving horizon volume compared to O3 — and even moreso for IMBHs close to 1000 solar masses.
The final plot gives range integrands for a variety of black hole systems ranging from 6 solar masses to 600 solar masses. More specifically, these range integrands are the ratio between the characteristic strain for each system and the detector's noise amplitude, which is the appropriate quantity if one wants to interpret the area under the curve on a log-frequency plot (see the discussion in Moore, Cole, & Berry).
These calculations were done with Jamie's excellent inspiral_range package, which is available on the control room computers and does computations with IMRPhenomD by default. The daily summary pages also give range calculations for several BBH systems (see, e.g., https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20230404/lock/range/).
Evan, Kevin and I reran the PUM DAC noise measurements for the noise budget. I have attached the full DARM noise budget and the PUM DAC sub budgets. The only change from January appears to be that the ETMX PUM DAC is flat from 10-20 Hz, unlike the other test masses. We have no idea why that would be, except for the different drive on ETMX compared to all other test masses.
As a reminder, we currently run all PUM DACs in state 3, that is, LP ON and Acq OFF. We do not dither the PUM DACs. I just posted an alog showing the results of a test of the PUM DAC dithers that shows that the dither has no effect on our DAC noise.
A bruco from the noise budget quiet time: https://ldas-jobs.ligo.caltech.edu/~elenna.capote/brucos/OAF_1364608498/
This is a bit old news since we have since implemented jitter cleaning and many other changes that will affect the noise, but I think it is useful still.