AFP flipper devices: Polarized 3He spin flipper and shorter wavelength neutron flipper

We describe the development of a polarized neutron device that combines a 3He neutron spin filter and a neutron spin flipper using adiabatic fast passage (AFP), to adiabatically reverse the 3He polarization and thus the neutron polarization with near perfect symmetry. A typical AFP sequence takes place in 2.5–7.5 ms, with the time for the 3He transition from P to -P-P much less, thus the neutron polarization is nearly perfectly reversed very quickly with only a 2×10-52×10-5 loss in 3He polarization per flip. We believe this device, the 3He “flipperizer” can become a standard option wherever a 3He spin filter is already in use. Our first on beam test was performed on MIRA at the new FRM-2 reactor in Garching using polarized 3He from HELIOS. We also briefly describe tests of a new neutron flipper based on AFP. This broad band neutron RF flipper was shown to create neutron flipping efficiencies of >99%>99% at a neutron wavelength of 0.4 Å. Neutron tests were performed on D3 (ILL) and on ROTAX (ISIS).