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Physics, Space Physics, physics.space-ph, Astrophysics, Instrumentation and Methods for Astrophysics, astro-ph.IM
Abstract:
We report on the results of the LISA Pathfinder (LPF) free-fall mode
experiment, in which the control force needed to compensate the quasistatic
differential force acting on two test masses is applied intermittently as a
series of "impulse" forces lasting a few seconds and separated by roughly 350 s
periods of true free fall. This represents an alternative to the normal LPF
mode of operation in which this balancing force is applied continuously, with
the advantage that the acceleration noise during free fall is measured in the
absence of the actuation force, thus eliminating associated noise and force
calibration errors. The differential acceleration noise measurement presented
here with the free-fall mode agrees with noise measured with the continuous
actuation scheme, representing an important and independent confirmation of the
LPF result. An additional measurement with larger actuation forces also shows
that the technique can be used to eliminate actuation noise when this is a
dominant factor.