Chow, JongDickson, JamesGossler, StefanGray, MalcolmLam, Ping KoyMcClelland, DavidMow-Lowry, CMoylan, AndrewScott, Susan MSearle, AntonySlagmolen, BramWette, KarlAbbott, BAdhikari, RanaAjith, PHuttner, S.H.Lockerbie, N.A.Saulson, PSavage, RSchwinberg, PSidles, J.A.Torres, CWhiting, B FZhang, LHeefner, JHosken, DaveHough, JHowell, EIvanov, A2015-12-081550-7998http://hdl.handle.net/1885/31010Data from the LIGO Livingston interferometer and the ALLEGRO resonant-bar detector, taken during LIGO's fourth science run, were examined for cross correlations indicative of a stochastic gravitational-wave background in the frequency range 850-950 Hz, with most of the sensitivity arising between 905 and 925 Hz. ALLEGRO was operated in three different orientations during the experiment to modulate the relative sign of gravitational-wave and environmental correlations. No statistically significant correlations were seen in any of the orientations, and the results were used to set a Bayesian 90% confidence level upper limit of Ωgw(f)≤1.02, which corresponds to a gravitational-wave strain at 915 Hz of 1.5×10-23Hz-1/2. In the traditional units of h1002Ωgw(f), this is a limit of 0.53, 2 orders of magnitude better than the previous direct limit at these frequencies. The method was also validated with successful extraction of simulated signals injected in hardware and software.200710.1103/PhysRevD.76.0220012015-12-08