Massive Neutrinos? Implications from the KARMEN experiment
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	                    Klaus Eitel
                            FZ Karlsruhe


Abstract:
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The neutrino experiment KARMEN is performed at the ISIS spallation
neutron source of the Rutherford Appleton Laboratory, England. The
detector is a 56t segmented liquid scintillation calorimeter, shielded by
several meters of iron, at a distance of about 17m from the neutrino
source.
Neutrinos are produced at ISIS within the decay chain of pi+ and mu+
decaying at rest. Together with the unique time structure of ISIS, this
provides well defined criteria to identify neutrino induced events.
The sensitivity of KARMEN to detect neutrino oscillations could be
enhanced significantly by an additional veto counter installed in 1996.
Results from the search for numubar->nuebar appearance with the upgraded
KARMEN2 configuration (since February 1997) are presented and compared to
other neutrino oscillation experiments, especially LSND.
Apart from the search for neutrino oscillations, KARMEN investigates
neutrino nucleus interactions.
In the time spectrum of so-called 'single prong' neutrino induced events
there is an anomaly which cannot be explained by neutrino interactions
nor conventional background sources. Therefore, a hypothesis of an
unknown massive, weakly interacting, unstable particle produced in rare
pion decays has been tested leading to a consistent description of the
experimental results. The latest status of this time anomaly together
with the working hypothesis will be presented and discussed.

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