A powerful source for ultra-cold neutrons constructed at the
Paul Scherrer Institut (PSI) in Switzerland is in the commissioning phase.
While the currently best ultra-cold neutron (UCN) source at ILL in Grenoble achieves about
10 UCN/cm3 in a typical experiment - and up to 100 UCN/cm3 close to the UCN
producing turbine - the new UCN source will deliver densities close to 1000 UCN/cm3 in a typical experiment.
The source will be operated by the
Neutrons are produced in a short pulse of the full 2 mA, 590 MeV PSI proton beam on a
spallation target. The fast neutrons are moderated, cooled, and finally down-scattered
into UCN in solid ortho-deuterium. UCN are extracted from the solid deuterium and guided
into a diamond-like carbon (DLC) coated large storage volume from which they can be extracted into experiments.
After the proton beam pulse, the production and storage volumes are separated by a shutter,
allowing for UCN storage times of the order of magnitude comparable to the lifetime of the free neutron.
The UCN source will feed an experiment for an improved measurement of the electric dipole
moment of the neutron
(nEDM). A sensitivity of better than 10-27e cm is envisaged,
providing one of the most sensitive tests of the Standard Model of particle physics (see