The CERN experimental programme  Searches for Neutrino Oscillations  The LSND experiment

The KARMEN experiment

The Karlsruhe-Rutherford Medium Energy Neutrino (KARMEN) experiment is being performed at the spallation facility ISIS of the Rutherford-Appleton Laboratory. An important difference with respect to LAMPF is that the ISIS beam is pulsed with a time structure consisting of two 100 ns long pulses separated by 320 ns (this sequence has a repetition rate of 50 Hz). Thus it is possible to separate neutrinos from muon and pion decay from their different time distributions with respect to the beam pulse.  

Figure: Plot of the LSND $\Delta m^2$ vs $\sin^22\theta$ favoured regions. The darkly (lightly)-shaded regions correspond to $90\%$ ($99\%$) likelihood regions after including the effect of the systematic errors. Also shown are $90\%$ confidence level limits from KARMEN (dashed curve), E776 at BNL (dotted curve) and the Bugey reactor experiment (dot-dashed curve).

 

The KARMEN experiment has observed no signal above the expected background providing no evidence for $\overline{\nu}_{\mu} - \overline{\nu}_{e}$ oscillations. The boundary of the region in the oscillation parameter plane excluded by this result lies approximately in the middle of the region favoured by LSND, hence there is no disagreement between the two experiments. The KARMEN experiment is being upgraded to increase its sensitivity to $\overline{\nu}_{\mu} - \overline{\nu}_{e}$ oscillations. Within two years, it should either confirm or disprove the LSND result.