Limits on Electron-Neutrino Oscillations from the GALLEX $^{51}$Cr Source Experiment

The recent result from the chromium source experiment carried out by the GALLEX collaboration implies interesting limits on the parameters $\Delta m^2$ and $\sin^22\theta$ describing neutrino oscillations. Values of $\Delta m^2~>~0.17$ eV$^2$ for maximal mixing and of $\sin^22\theta > 0.38$ for $\Delta m^2 > 1$~eV$^2$ are ruled out at 90\% C.L. This result improves by more than an order of magnitude previous limits on $\Delta m^2$ derived from electron-neutrino oscillation experiments at accelerators.