Solid deuterium and UCN factory: application to the neutron electric dipole moment measurement

Present experiments which search for an electric dipole moment (EDM) of the neutron use ultra-cold neutrons (UCN) and are limited by counting statisti cs. One way to solve this problem is to improve the source of UCN. The pres ent article briefly reviews two possibilities which employ solid deuterium at the temperature of liquid helium. The possibility of installing a solid deuterium UCN source at the FRM-II reactor and at spallation neutron source s at PSI, LANL and KEK is discussed. An increase of the UCN density up to t he level of 10(3)-10(4) cm(-3) is expected. Compared to existing sources, t his corresponds to an improvement by two to three orders of magnitude. Such experimental facilities will make it possible to improve measurements of t he EDM of the neutron down to the level of 10(-27) e cm. (C) 2000 Elsevier Science B.V. All rights reserved.