## 3 Results and Discussion  
The successful synthesis of MnO\({}_{2}\) NPs by the hydrothermal process is shown by the TEM image and EDS (Energy Dispersive Spectrometry) data of the nanostructured MnO\({}_{2}\) powder (Figure 1). It can be seen from the TEM images that the nanostructured MnO\({}_{2}\) powder exhibits rod-like structures that consist of nanofibers with a diameter of 50 nm. Form the EDS data, the atomic percentage (%) of Mn element and O element was 31.3% and 62.5%, respectively (Figure 1c). After neutron irradiation, the morphology of the MnO\({}_{2}\) was not changed. This result means that the nanostructured MnO\({}_{2}\) showed high stability under neutron irradiation. The successful preparation of the MnO\({}_{2}\) NPs before and after neutron irradiation is also shown by the XRD data (Figure 2). All the peaks assigned by the diffraction of crystalline MnO\({}_{2}\) at 2\(\Theta\) = 28.7\({}^{\circ}\), 37.4\({}^{\circ}\), 41.0\({}^{\circ}\), 42.8\({}^{\circ}\), 46.1\({}^{\circ}\), 56.7\({}^{\circ}\), 59.4\({}^{\circ}\), 64.9\({}^{\circ}\), 67.3\({}^{\circ}\), and 72.3\({}^{\circ}\) correspond to the (110), (101), (200), (111), (210), (211), (220), (002), (310), and (301) planes (JCPDS card 71-0071). All the diffraction peaks correspond well with standard crystallographic data and can be indexed primarily to the pure tetragonal structure of \(\beta\)-MnO\({}_{2}\) (JCPDS card 00-024-0735). Figure 1: TEM (transmission electron microscopy) and EDS (energy dispersive spectrometry) data of the nanostructured MnO\({}_{2}\) before and after neutron irradiation. A neutron activation analysis of the prepared nanoparticles was carried out at the HANARO research reactor (neutron flux: 4.2 \(\times\) 10\({}^{13}\) n\(\cdot\)cm\({}^{-2}\cdot\)s\({}^{-1}\)), a nuclear research reactor at the Atomic Energy Research Institute. A 3.7-mg sample was activated for 20 s, and the gamma spectrum was then measured after cooling for 10 min. The peaks in the gamma spectrum were assigned to the characteristic gamma energies of Mn-56 (Figure 3). The results showed that the radioisotope was successfully synthesized by neutron irradiation after hydrothermal synthesis of the nanostructured MnO\({}_{2}\) NPs. In order to obtain nanostructured Sm\({}_{2}\)O\({}_{3}\) powder, first nanostructured SmOH was synthesized by the W/O emulsion process. Then, to obtain pure Sm\({}_{2}\)O\({}_{3}\) powder, the SmOH powder was calculated at 900 \({}^{\circ}\)C for 2 h under an air atmosphere. The Sm\({}_{2}\)O\({}_{3}\) powder was successfully synthesized by the microemulsion process and the calcination process, as shown by the TEM image and EDS data of the Sm\({}_{2}\)O\({}_{3}\) powder after calcinations (Figure 4). All of the Sm\({}_{2}\)O\({}_{3}\) nanopowder had a rod shape with the dimensions of 36 \(\times\) 185 nm. As shown by the EDS data, the percentage (%) of Sm element and O element was 31.3% and 62.5%, respectively. After the neutron irradiation, the morphology of the Sm\({}_{2}\)O\({}_{3}\) powder was changed from a rod-like structure to an amorphous structure. Figure 3: Gamma spectrum of the radioisotope MnO\({}_{2}\) nanoparticles (NPs) prepared by neutron irradiation. Figure 2: X-ray diffractometer (XRD) data of the nanostructured MnO\({}_{2}\) before and after neutron irradiation. XRD data of the Sm\({}_{2}\)O\({}_{3}\) powder after the calcination process (Figure 5) showed that the diffraction peaks of the Sm\({}_{2}\)O\({}_{3}\) powder were very weak, indicating an amorphous structure. All the peaks assigned by the diffraction of crystalline Sm\({}_{2}\)O\({}_{3}\) at 2\(\Theta\) = 19.9, 28.3, 32.8, 47.0, and 55.7\({}^{\circ}\) correspond to the (211), (222), (400), (440), and (622) planes (JCPDS card 43-1029). Evident broad peaks were a mixture of the amorphous and nanocrystalline nature of the samples. For gamma spectroscopy analysis, a 5.42 mg sample of the as-prepared Sm\({}_{2}\)O\({}_{3}\) powder was activated for 10 s by neutron irradiation, and the gamma spectrum was then measured after cooling for 10 min.