The 15th-18th Terracotta Doll Investigation Using a Compact Neutron Tomography System at Thai Research Reactor

Abstract

It is well known that neutron imaging is a powerful nondestructive technique in archaeological studies, especially for visualization of organic contents or low-density parts inside antiques. In Thailand, the neutron imaging system has been developed to perform neutron tomography (NT) for archeological studies since 2015. A compact NT system, which is composed of a CCD camera coupled with a LiF/ZnS fluorescence screen and an in-house developed rotation stage, was used to investigate the internal structure of an object. The experiment was set up at Thai Research Reactor (TRR-1/M1) of Thailand Institute of Nuclear Technology (Public Organization) with the power of 1.2 MWth. The neutron intensity at the radiographic position was about 10 6 n.cm -2 s -1 . In this work, an ancient sample of interest, namely, the 15 th -18 th century terracotta doll was investigated to perform the developed NT system. The resulting 2D neutron image showed a crack at the neck and a small gravel inside the body. Then, the projections were reconstructed by means of the Octopus Imaging software. Even with the compact NT system (L/D: 50), the 3D neutron image of the ancient doll was successfully reconstructed. The image revealed some hidden organic materials coated on the neck of the doll. Moreover, the elemental composition of the terracotta doll was analyzed by using X-ray fluorescence technique. The result could further inform the historical records of the ancient doll.