Energetic proton acceleration from interaction of intense circularly polarized laser pulse with a foam-carbon foil target is investigated using two-dimensional particle-in-cell simulation. It is found that protons from this target are accelerated to much higher energy in comparison with double-layer targets and simple flat targets. This result can be attributed to an enhancement of energy conversion efficiency from laser to electrons inside foam region. When a large number of energetic electrons are generated from the nearcritical plasma, they transport through the foil and form a strong backside sheath field which accelerates protons more efficiently.

Understanding moisture transport is an important step in the study of the durability of cement-based materials. A neutron imaging detection method for water transport in cement-based materials, based on a compact neutron source is provided. We visualize the moisture transport and obtain the capillarity coefficients for different cement-based materials using PKUNIFTY.

Coded source imaging (CSI) is a possible method to solve the contradiction between neutron flux and L/D ratio. Peking University neutron imaging facility (PKUNIFTY) is a RFQ accelerator based facility. The CSI experiments were carried out on PKUNFTY to test the benefits that this technique might bring. The CSI technique gets more restricts on the moderator, especially the neutron distribution in the inner collimator, where the coded mask sampling the source. The effect caused by the non-uniformity of neutron distribution on the mask plane was investigated. The slope type non-uniformity should less than 20% to keep the artifact in the reconstructed image insignificant. The PKUNIFTY moderator was modified according to the above limit. The preliminary experiments shown the moderator design for coded source imaging is acceptable.

Reconstruction of limited-view CT is an ill-posed inversion problem. In order to suppress the artefacts and improve the image quality, it has been proved to be a good method toincorporatesome aprioriinformation of the sample(refers to as constraint in this paper) to the iterative process. In this paper, sample boundary is considered as a constraint and SART algorithm is chosen to test the performance of the constraint. Reconstructions from different number of projections of the famous Shepp-Logan head phantom with different levels of noise were simulated; projection data of a spark plug was acquired on the cold neutron CT platform of China Advanced Research Reactor (CARR) and the spark plug was reconstructed as well. Both the simulation and experimental results show that SART algorithm with sample boundary constraint leads to remarkable improvement of image quality and convergence speed for limited-view CT reconstruction when the noise level of projection data is less than 5%.