摘要
编码中子源成像可以在对中子注量率影响不大的情况下大大提高成像的准直比,从而提高成像质量.北京大学开展了基于小型加速器的编码中子源成像技术研究工作.不同于已有的基于反应堆的小面积编码板的研究工作,北京大学建立了基于小型加速器的大面积编码板的编码中子源成像实验平台,并对加速器中子源上的实验方法和数据处理进行了探索,对比了重建算法,获得了初步的重建照片.研究工作表明,编码中子源成像技术可用于加速器中子源,但重建图像质量仍须提高.
Compact accelerator based neutron source has lower cost and better flexibility than nuclear reactor. Neutron imaging using such a neutron source has attracted more and more attention in recent years, in spite of its relatively low neutron fluence. In order to keep a definite neutron flux above a reasonable level on a compact accelerator based neutron imaging system, one could not set the collimation ratio to be as high as the reactor neutron source to obtain a high resolution. Coded source could increase the collimation ratio without reducing the neutron flux much. It may benefit neutron imaging system in the case of low yield neutron source. Since 2005, several laboratories in Germany and USA have carried out simulation and experiments of coded source neutron imaging. Those experiments are based on the reactor neutron sources, which have high neutron yield and low scattered neutron background. Recently, a preliminary coded source neutron imaging experiment was carried out on PKUNIFTY （Peking University Neutron Imaging Facility）, which is based on a 2 MeV deuteron RFQ accelerator. It is the first time that coded source neutron imaging has been applied to an accelerator-based neutron source. Projections of coded neutron source are taken with a neutron yield of 2.6 x 1011 s-1. With Wiener filter deconvolution and Lucy-Richardson maximum likelihood iteration algorithm, the experimental projections are reconstructed successfully. Because the accumulated neutron fluence is low and the neutron background is high, the signal-to-noise ratio of reconstructed images is not good enough, which will be improved by reducing the neutron background.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2013年第12期167-173,共7页
Acta Physica Sinica
基金
国家重点基础研究发展计划(批准号:2010CB833106)
北京大学仪器设备基金~~
关键词
加速器中子源
中子成像
编码源成像
图像重建
accelerator-based neutron source
neutron imaging
coded source imaging
image reconstruction
