Tests of a silicon wafer based neutron collimator

A Soller slit neutron collimator has been prepared by stacking 160 μm thick single crystal silicon wafers coated on one surface with 4 μm of gadolinium metal. The collimator has an angular width of 20 min full width at half maximum and an effective length of 2.75 cm. The collimator has beam dimensions of 1 cm wide by 5.3 cm high. Tests at neutron wavelengths 7.5Å and 1.8Å showed a peak transmission of 88% within 2% of the optimum theoretical possibility. The background suppression in the wings is comparable with that of conventional neutron collimators.