Short-Range Inverse-Square Law Experiment in Space

The objective of ISLES (Inverse-Square Law Experiment in Space) is to perform a null test of Newton's law in space with a resolution of one part in 10⁵ or better at 100 m. ISLES will be sensitive enough to detect axions with the strongest allowed coupling and probe large extra dimensions of string theory down to a few m. The experiment will be cooled to 2 K, which permits superconducting magnetic levitation of the test masses. This soft, low-loss suspension, combined with a low-noise SQUID, leads to extremely low intrinsic noise in the detector. To minimize Newtonian errors, ISLES employs a near null source, a circular disk of large diameter-to-thickness ratio. Two test masses, also disk-shaped, are suspended on the two sides of the source mass at a nominal distance of 100 m. The signal is detected by a superconducting differential accelerometer.