Neutron Optical Beam Splitter from Holographically Structured Nanoparticle-Polymer Composites

We report a breakthrough in the search for versatile diffractive elements for cold neutrons. Nanoparticles are spatially arranged by holographical means in a photopolymer. These grating structures show remarkably efficient diffraction of cold neutrons up to about 50% for effective thicknesses of only $200\mu \mathrm{m}$. They open up a profound perspective for next generation neutron-optical devices with the capability to tune or modulate the neutron diffraction efficiency.

Figure 1

Diffraction regimes separated by gray dash-dotted lines and experimental results for $\mathrm{S}0$ (red squares), $\mathrm{Z}0$ (blue triangles), and $\mathrm{S}7$ (red circles) measured with thermal and cold neutrons. For comparison $d$-PMMA ($d=3500\mu \mathrm{m}$, $\Lambda =381\mathrm{nm}$, $\lambda =2.7\mathrm{nm}$) is shown. Dashed or solid diagonal arrows indicate a change in $d$ or $\lambda$.

Figure 2

Angular dependence of the 0th and $\pm 1$st order diffraction efficiencies for cold neutrons at $\lambda =2\mathrm{nm}$ for gratings assembled from a ${\mathrm{SiO}}_2$ nanoparticle-polymer composite with a spacing of $\Lambda =500\mathrm{nm}$ and an effective thickness of $d=203\mu \mathrm{m}$ ($\mathrm{S}7$). Lines are a simultaneous RCWA fit to the data. Inset: Detector matrix (gray scale of logarithmic box counts at Bragg positions).