A new detector, the Fermilab Holometer, consists of separate yet identical 39-meter Michelson interferometers. Strain sensitivity achieved is better than ${10}^{-21}/\sqrt{\mathrm{Hz}}$ between 1 to 13 MHz from a 130-h data set. This measurement exceeds the sensitivity and frequency range made from previous high frequency gravitational wave experiments by many orders of magnitude. Constraints are placed on a stochastic background at 382 Hz resolution. The $3\sigma$ upper limit on ${\mathrm{\Omega }}_{\mathrm{GW}}$, the gravitational wave energy density normalized to the closure density, ranges from $5.6\times 10^{12}$ at 1 MHz to $8.4\times 10^{15}$ at 13 MHz. Another result from the same data set is a search for nearby primordial black hole binaries (PBHB). There are no detectable monochromatic PBHBs in the mass range $0.83–3.5\times 10^{21}\mathrm{g}$ between the Earth and the Moon. Projections for a chirp search with the same data set increase the mass range to $0.59-2.5\times 10^{25}\mathrm{g}$ and distances out to Jupiter. This result presents a new method for placing limits on a poorly constrained mass range of primordial black holes. Additionally, solar system searches for PBHBs place limits on their contribution to the total dark matter fraction.

• Received 16 November 2016

DOI:https://doi.org/10.1103/PhysRevD.95.063002