  Magnetic hopfions are three-dimensional localized magnetic topological
solitons which can exist in the bulk of magnetic materials. Based on a Ritz
model for magnetic hopfions in a chiral magnet, the unpolarized magnetic
small-angle neutron scattering (SANS) cross section, the spin-flip scattering
cross section, and the chiral function (characterizing the imbalance between
the two spin-flip scattering amplitudes) are computed here analytically; while
the real-space correlation function is obtained numerically. Features of these
functions, specific to magnetic hopfions, are discussed. Our results enable the
SANS method to be used for the detection of magnetic hopfions.
