The Study Of Material Composition Using Monte Carlo Simulation Of Compton Backscattering

Compton Scattering is a scattering effect which takes place between high energy photons and electrons (free electrons or atomic electrons).From the analysis of the scattered signal, we can obtain the electron density distribution of the examined sample or that of the human tissues. If the measured electron densities are arranged according to their real spatial position, the 2-D or the 3-D image corresponding to the electron density can be obtained. Comparing with the traditional transmission tomography, the Compton Scattering imaging technique has some superiority such as high sensitivity, more freedom in the arrangement of experimental setup. Since the 1970s. Compton scatter imaging technology in industrial applications has entered a rapid development stage, and gradually shift the focus of the study backscatter imaging technology. Compton backscatter imaging is radioactive sources and detectors will be placed in the ipsilateral of the scattering ,measurement of scattering from the object out-ray Compton Scattering, getting the electronic distribution image of the material within the objects. When measures only take place on the surface of the object, or it is not possible to place radioactive sources and detectors on the opposite side of the detected objects, this feature seems particularly important. Compton scatter imaging has a wide application, and it is potential for development, it is a hot research at home and abroad. First this paper have a lot of investigation and study on Compton backscatter imaging technology, then followed by a corresponding experimental and simulation computing. The experiments is using theγ-rays with 0.662MeV energy radiate the aluminum, iron, copper, Plexiglas's material four samples, NaI detectors was used in a certain distance to detect the information of the scattering photons on different angles.At the same time. MCNP4C Monte Carlo procedure was used to simulate the early Compton scattering experiment in the thesis. MCNP4C Monte Carlo procedure is a new version of the MCNP Monte-Carlo program developed by the Los Alamos National Laboratory of the United States, which is used extensively in the simulation of particle transport. MCNP code is an important characteristic of flexible, and easy to use. Papers reproduced the environments and conditions of the Compton scattering experiments as far as possible in the MCNP.First of all. we simulate Compton scattering experiments and compare the results of the simulation experiments with the experimental data. We found that the experimental results match the results of the simulation results, so we can operations that Compton scattering experiments and simulation computing MCNP the results are correct, the data is reliable. On this basis, we also simulated operation of the above four samples of Compton scattering backscattered photons information, through an analysis of information of the backscattered photons the scattering of the material and preliminary shape can be identified, also we can analyze the composition of scattering material. If machines can reach a certain precision, and a detector array and disconsolation techniques can be adopted, we can achieve the Compton scattering backscatter imaging of scattering samples. Compton scattering studies have proved that the other aspects of the application will also have a big space for development. All need to determine the density and the atomic number of related issues, can consider using the Compton scattering to resolve. We can not only by the material Compton scattering to analyze the composition of substances, such as the purity of medicines, as well as the size alloy content, but also can be used to detect hidden bombs or drugs in suitcase or car door or dissection or e-mail and detect pavement thickness, density and water content roadbed, etc.