Search for Gravitational Radiation at 145 Hz

We present the results of gravitational radiation experiments with two 1400-kg antennas at ${\nu }_0=145\mathrm{}$ Hz. The square antennas, 1.65×1.65×0.19 ${\mathrm{m}}^3$, $Q_M\simeq 2.0\times {10}^5$, with electrostatic transducers of $\beta \simeq 1.8\times {10}^{-3\mathrm{}}$, have mean effective noise energy $\overline{D}\simeq 0.034k{T}_r$. The observed cross correlation of the outputs of the two detectors gives an upper limit for the relation between the mean energy spectrum density $F\left({\nu }_0\right)$ and the daily occurrence rate ${\dot{N}}_G$ of gravitational radiation pulses: $F\left({\nu }_0\right){{\dot{N}}_G}^{\frac{1}{2}}<~\left({3.6}_{-1.4\mathrm{}}^{+1.0\mathrm{}}\right)\times {10}^6$ J ${\mathrm{m}}^{-2\mathrm{}}$ ${\mathrm{Hz}}^{-1\mathrm{}}$ ${\mathrm{day}}^{-\mathrm{½}}$.