Method for determination of spin reverse probability in neutron transition through a spin-flipper

Theoretical considerations are given on the analysis of thermal neutron beam polarization with spin-flipper having a zero field in the form of a straight line. The case of polarization efficiencies of a polarizer and ap analyzer being abaUt Unity is reparted. This fact allowed one to write much simpler formula for r-ratio and thus made the interpretation of experimental results easier. The formula is given for the probability f of neutron spin reverse with spin-flipper. It is noted that f has a squared dependence on the cross shift of the spin-flipper with respect to the neutron beam. It is proved here that to find f and the product of the polarization efficiency of polarizer Psub(p) and that of polarizer Psub(A), is enough to measure the dependence of r-ratio on the spin-flipper cross shift. It is shown that measurements without neutron energy analysis give spectrum values averaged over the above quantities. It is noted that some features of f-function make in some cases possible to derive its dependence on neutron wave-length