Phase contrast imaging which is based on the wave character of neutron beam, is an advanced technique in neutron imaging field.
相衬成像是中子成像领域内的前沿技术，它的成像机理基于中子束的波动性。
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Theoretically, when gas exists in reservoir, longitudinal wave offset time will increase and transverse wave offset time will not change and density will decrease and neutron will decrease, too.