## 5 Results  
Image analysis provided several interesting features related to the microcrystalline structure of the single crystal copper rod. First, the attenuation profile in different areas of the sample did not show Bragg edge profiles, which are typically found for polycrystalline systems. However, multiple dips in the attenuation spectra were observed. Figure 1 shows a few monochromatic transmission radiographs, from which it can be observed that the rod is not a complete single crystal since dark areas are visible at specific wavelengths. In addition to the misaligned areas, appearing as dark spots, a structured branch figure is clearly visible. Figure 1: Monochromatic radiographies of the copper rod taken respectively at **(A)** 3.850 Å, **(B)** 3.725 Å, **(C)** 3.575 Å. The presence of black spots is evident in images (**B**,**C**) as well as a structured branch coherent volume in image (**C**). Image (**A**) also shows the areas used to select transmission intensity profile reported in Figure 2. We set as \(x\) direction the horizontal one and as \(y\) direction the vertical one. Single crystal grow direction from right to left. In Figure 2, we show some transmission profiles taken in different sample areas using a rectangular region of interest with size 60 \(\times\) 15 pixels, showing the presence of Bragg dips which width is compatible with the neutron wavelength resolution. The results are compared with the typical polycrystalline copper Bragg edge profile measured on a reference sample acquired on the same radiography scan window. According to more than 30 sampled areas, the selected windows are representative of the whole volume of the sample, showing the dips profile and the position of the most significant crystallization typologies. Different areas of the sample exhibit the presence of dips at various wavelengths. It is generally difficult to assign a dip to specific lattice plane family but, in specific cases, it becomes possible; i.e., the rightmost dips in green and black spectra in Figure 2 can only be reflections of 111 lattice planes since the wavelength is larger than all reflections except 111. The results of the wavelength fit of the dips shown in Figure 2 are reported in Table 1, including the possible relative lattice plane assignment and the angular displacement (\(\theta\)) of the planes with respect to the primary neutron beam. Figure 2: Transmission spectra as a function of neutron wavelength in selected sample areas showing that no evidence of Bragg edge structure is visible at all while a set of three or more broad dips are visible. The slight tilt of the reference value is related to the linear increase of the absorption cross section of copper with neutron wavelength. The experimental profile of Bragg edge originated by polycrystalline isotropic pure copper solid sample is shown in blue lines. The 111, 200, 220 Bragg edges are evident, ideally positioned respectively at 4.174, 3.6147 and 2.556 Å. Considering there is a certain wavelength dispersion within the field of view due to the double crystal monochromator behaviour, it is reasonable to consider that the dips #1 and #3 of the spot free area coincide with the dips #1 and #5 of the end cap area. Thus, in this area we observe a mixture of a set of differently oriented single crystal blocks. Another way to qualitatively observe the behaviour of the recrystallization procedure is the analysis of re-sliced images of the wavelength scan stack performed starting from the top according to the coordinates of Figure 1 (negative y direction). In this way, each image represents the x-\(\lambda\) view of the rod taken at a specific y height. Three different images taken respectively in the top area, the branched dendrite area and the bottom area of the rod, with respect to the y direction of Figure 1 are shown in Figure 3; the external caps were cut to ease visualization. In the top and bottom images, the presence of three main dips along the rod length shows the reflections related to the bulk single crystal.