  Recently, observational searches for gravitational wave background (GWB) have
been developed and given constraints on the energy density of GWB in a broad
range of frequencies. These constraints have already resulted in the rejection
of some theoretical models of relatively large GWB spectra. However, at 100
MHz, there is no strict upper limit from direct observation, though an indirect
limit exists due to He4 abundance due to big-bang nucleosynthesis. In our
previous paper, we investigated the detector designs that can effectively
respond to GW at high frequencies, where the wavelength of GW is comparable to
the size of a detector, and found that the configuration, a so-called
synchronous-recycling interferometer is best at these sensitivity. In this
paper, we investigated the optimal location of two synchronous-recycling
interferometers and derived their cross-correlation sensitivity to GWB. We
found that the sensitivity is nearly optimized and hardly changed if two
coaligned detectors are located within a range 0.2 m, and that the sensitivity
achievable in an experiment is far below compared with the constraint
previously obtained in experiments.
