Design of ellipse focusing mirror for neutron powder diffraction complex

To meet the requirement of small sample studies on the neutron diffraction complex, a one-dimensional ellipse focusing mirror system was designed and its parameters were optimized. The effects of elliptical focusing mirror parameters on the neutron flux at sample were evaluated by both employing elliptical analytical calculation and neutron tracing simulation package McStas. And the optimal parameters of the mirror for the maximum neutron flux were investigated and obtained. The results show that in the source (left ellipse focus) to the sample (right ellipse focus) distance of 2.7 m, the super mirror factor of 3 and the mirror length of 25 cm case, the optimum right-position of the ellipse mirror is at distance 560 mm from sample and the half long axis is 1 350.016 mm. In optimized condition, the neutron flux at the sample can be improved 7 times.