The influence of swift heavy ion (SHI) irradiation on the photoluminescence (PL) of silicon nanoparticles (SiNPs) and defects in SiO-film is investigated. SiNPs were formed by implantation of 70 keV Si and subsequent thermal annealing to produce optically active SiNPs and to remove implantation-induced defects. Seven different ion species with energy between 3-36 MeV and fluence from 10-10 cm were employed for irradiation of the implanted samples prior to the thermal annealing. Induced changes in defect and SiNP PL were characterized and correlated with the specific energy loss of the employed SHIs. We find that SHI irradiation, performed before the thermal annealing process, affects both defect and SiNP PL. The change of defect and SiNP PL due to SHI irradiation is found to show a threshold-like behaviour with respect to the electronic stopping power, where a decrease in defect PL and an anticorrelated increase in SiNP PL after the subsequent thermal annealing are observed for electronic stopping exceeding 3-5 keV nm. PL intensities are also compared as a function of total energy deposition and nuclear energy loss. The observed effects can be explained by ion track formation as well as a different type of annealing mechanisms active for SHI irradiation compared to the thermal annealing.
The performance of neutron tomography facility at the Thai Research Reactor TRR-1/M1 is studied. Thermal neutron beams with a flux of 106 n/cm2/s are employed to radiate on a standard sample, so-called Strip B, in the test. The neutron irradiating on samples were detected by a neutron-to-photon conversion plate. After that, the low-energy photons were guided to a charge coupled device (CCD) to obtain a digital image. During the experiment, a rotation stage was used to rotate the sample in order to measure the attenuated/scatted neutrons at different angles with respect to the sample geometry. The angle-varied images were then processed via a reconstruction software to create a 3-dimension (3D) image (tomography). The result shows that an image of 0.5 mm-diameter cadmium wire could be observed by employing our facility, but the sharpness of the 3D image is still needed to be further improved.
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