Multilayer cold-neutron pulser working under a very low magnetic field

Multilayer cold-neutron pulser has been developed which works under an external magnetic field less than 30 Gausses. Permalloy/Ge multilayer (PGM) have been evaporated on Si wafer in the magnetic field of about 130 Gausses parallel to the surface of the wafer. A cold neutron pulse was obtained from the PGM mirror placed in a pulsed magnetic field of 15 Gausses which is called a multilayer cold neutron pulser, or in abbreviation a cold neutron pulser. A neutron pulse rise time was 300 μ s with rather longer lag compared to 100 μ s of a current pulse supplied to the magnetic coil. The compact cold-neutron optical system could be constructed using such a device functioning under a low external magnetic field since the stray field from the device is very low. The cold neutron pulser was applied to a delayed choice experiment which is related to the observation problem in quantum mechanics. The results suggested the feasibility of this device as a switching device for the delayed choice experiments. (author)