A novel pyrolytic-graphite-on-silicon device for neutron monochromatization

Recent studies of highly oriented pyrolytic graphite and hybrid graphite-silicon monochromator systems

“…Mechanical and both x-ray and neutron diffraction tests using the device shown in fig. 6 confirmed that this new type of monochromator with precise, tunable curvature can be safely used in neutron instrumentation [12]. A photograph of the assembly is presented in fig.…”

“…In an attempt to achieve dynamical focusing by a variable curvature of the HOPG crystals, the bendability of Momentive grade ZYA crystals was studied as a function of their thickness and curvature. To achieve a minimum radius of 1.5m without breakage the thickness had to be inferior to 0.1mm, but even then a non-zero risk of damage after several bending and flattening cycles remained [12]. The results also showed that the elasticity limit was sample dependent.…”

Highly aligned pyrolytic graphite blades for neutron monochromatization

“…By calculating the average of |Δ𝜃 𝑖 |, it can be found that the miscut angles between the surface and lattice planes are 0.03 • ∼ 0.04 • for the five highly aligned pyrolytic graphite blades. It was observed that Δ𝜃 𝑖 for the highly aligned pyrolytic graphite blade C4 has a same sign, presenting a global curvature as defined in reference [13], and Δ𝜃 𝑖 for the other blades C1, C2, C3 and C5 is positive or negative randomly, presenting wavy shapes. As an example, the peak positions for C2 and C4 with a wavy shape and with a global concave curvature, respectively, are presented in figure 7.…”

“…A novel bonding method has been developed for spectrometer Pelican [11] using pure indium to solder two layers of HOPG crystals directly, and then to solder HOPG crystals on Si blades [12,13]. Indium has a sizable neutron absorption cross-section and produces gamma rays after activation.…”