Realizing a (nearly) 100% neutron beam polarization

Abstract

We report a neutron beam polarization P = [99.9982 ± 0.0024]%, which means an improvement of two orders of magnitude compared to known values. Actually, one can assume this neutron beam to be 100% polarized, because due to the special beam guidance the overlap of spin-up neutrons and spin-down neutrons could be suppressed down to 1.2 × 10 −12 [rel. units]. These values are about four orders of magnitude below the detection limit of a monochromatic neutron flux of 10 8 n• cm −2 s −1 .