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 10(5) or better at 100 mum. 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 mum. The experiment will be cooled to less than or equal to2 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 mum. The signal is detected by a superconducting differential accelerometer.