A Superconducting Storage Ring for Very Slow Neutrons

It was shown experimentally that neutrons can be confined in a magnetic storage ring by means of their magnetic moments. Due to the small dipole moment the energy of the neutron is limited to a few 10-6 eV in spite of the high field in the superconducting magnet of 1 m diameter. In many respects the beam dynamics are similar to a storage ring for charged particles. The basic field configuration is a sextupole field superimposed of a strong decapole term in order to overcome imperfaction resonances by a non harmonic potential. As only neutrons in one spin state are confined, care has to be taken to avoid spin flips. The neutrons are injected by a totally reflecting mirror system which can be removed out of the confinement region. Neutrons were detected up to a storage time of 45 min. Their number decreases according to their lifetime (τ1/2=10.6 min) due to radioactive decay.