Neutrinos are produced by
decay in fission fragments, so the energy of the neutrinos is below 10
Mev. A good knowledge of the reactor parameters is needed to obtain the
neutrino flux emitted by a reactor. The energy spectrum and the flux of
produced by a reactor have been carefully measured above 2 Mev using detectors
close to the reactor core. In the inverse
decay reaction on proton (threshold 1.8 Mev):
the neutrino energy is deduced from the e+ energy. The
experimental accuracy on the neutrino flux is
to be compared with
on the expected flux. Below 2 Mev the
spectrum can only be calculated. Uncertainties from the contribution of
the neutron capture in fission fragments have been calculated recently.
This is important for experiments searching for neutrino magnetic moment
effect in neutrino electron elastic scattering. Many sites have been used
around the world, but few are still in operation for neutrino studies.
Laboratories which are close to the reactor core are now used to measure
very low cross section processes (neutrino electron or neutrino deuteron
scattering). In these experiments the value of the
flux (reactor power) is more important than the overburden. The search
oscillation imposes now long baseline experiments: the overburden and the
reactor power are significant. Comparisons between available sites are
shown in table .
Table: Parameters of the available neutrino sites near reactors