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The original experimental scheme required the electrical field to be planar to  within 10 nanoradians to achieve the goal sensitivity of 10-24 e-cm.

Newer schemes, using, for example, a central electric field structure with the beam circulating in both directions, relax the planarity requirement appreciably. However, it is still necessary to monitor the direction of the E field to the order of microradians or less, and to establish the effect of known changes generated in the tilt of the E field.

The Jones differential capacitor device was suggested by Francis Farley who knew of the work of his fellow Fellow of the Royal Society. (See, e.g., Journal of Physics E: Scientific Instruments 1973, Vol 6, p 589.) The intrinsic sensitivity of this instrument appears to be limited only by quantum mechanical considerations; sensitivity better than 10-10 radians was demonstrated decades ago. 

The differential capacitor approach offers extreme simplicity, great sensitivity, and modest cost. The first development phase is to incorporate modern electronics, and to demonstrate sensitivity of 100 nanoradians, sufficient to observe earth tides at BNL. The second development phase will explore the use of modern materials unavailable when the device was first developed almost a half century ago.

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Last update on: October 30, 2009

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