Cheryl, Jeff, Eric

We carried out the first successful demonstration of CW injection with aLIGO.  Previously, we have tested the injection code, but we hadn't been able to confirm that the injections were making it into the detector.  Cheryl and Jeff put H1 in a low-noise DC state with ~30 Mpc inspiral range.  The intent bit was turned on.  We turned on the injections at 22:19:20 to confirm that the excitation showed up in the filter bank.  However, the injection amplitudes are too weak to show up by eye in the spectrum (by design) and so we prepared to increase the amplitude.

For the second test, which started at 22:26:44, we made one of the injections 10x louder than the others so it would show up as a sharp line.  We chose to carry out the test with Pulsar #0, which has a frequency of f0 = 265.5771052 Hz and a strain amplitudes of aPlus=2.0125e-25, aCross=1.960625e-25.  We increased these values of aCross and aPlus by a factor of ten and restarted the injections.  Jeff could not see them by eye in the control room spectrum.  We increased the gain on the injection channel until we Jeff could be absolutely sure he saw a CW line.  (For CW/detchar people looking at this data, you will see the signal get louder according to step function factors of ten.)  Jeff could clearly see the line when we set the gain to 200, corresponding to strain of ~2e-25 x 10 x 200 = 4e-22 or displacement of 1.6e-18m.  We confirmed that the measured displacement approximately matched the value predicted by the pulsar injection configuration file.

We turned off the injections in order to restart them with a lower amplitude.  However we lost lock before we restart.  The injections ended sometime not long after GPS = 1116912836.

In the course of this test, we found a good preliminary value to use for the HWINJ LIMIT.  In order to avoid clipping, we set LIMIT=200.  This allowed us to create a strong line.  The output of the control loop during this time was O(10,000).  I suggest that we use LIMIT=200 as a new default and see if that gives us enough range for our transient injections.