Abstract :
Free neutron beta decay provides sensitive tests of the Standard Model of electroweak interaction. A particular class of experiments has now reached a limit set by the imperfect knowledge of the neutron polarisation and of the efficiency of a spin flipper. Standard techniques of polarisation analysis reach a precision of ≥0.25%. In a recent experiment it was shown that an accuracy on the level of a few times 10−4 can be reached within a classical scheme of polarisation analysis, using an opaque spin filter as analyser. In this letter a new scheme is given which takes advantage of a natural degree of freedom of spin filters, resulting in a more sensitive and simpler measurement of neutron polarisation and flipper efficiency.
