DC Cancellation As a Method of Generating a t² Response and of Solving the Radial Nonobservability Problem in a Concentric Free-Falling Two-Sphere Equivalence-Principle Experiment in a Drag-Free Satellite

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This paper has been submitted for publication. It may be downloaded from this website at Long DC-Cancellation Paper (PDF) or from the Los Alamos Archives as paper gr-qc/0005073 (PDF).

This paper gives the detailed design, performance calculations, expected cancellation accuracy, and the disturbance errors for DC Cancellation as a method of solving the two problems which have prevented a true free-fall Equivalence-Principle (EP) experiment in a Drag-Free satellite for 25 years now.

These problems are

1. A small semimajor axis error between the the two proof masses cannot be distinguished even in principle from an EP violation. The tolerance of the semimajor-axis error is so small that an EP experiment in a satellite is essentially impossible without some kind of countermeasure.

2. The separation between the proof masses due to an EP violation or a semimajor-axis error only grows as t not t². This means that the signal is much smaller and that the biggest disturbance (gas Brownian motion which grows as t^3/2) will keep the experiment from improving versus averaging time.

See the special section on the two problems for more details.

DC Cancellation solves both of these problems. The exact result depends on the cancellation accuracy, but the DC Cancellation experiment essentially becomes equivalent to a drop tower about 1 AU tall.