Izumi N, Hall G N, Carpenter A C, Allen F V, Cruz J G, Felker B, Hargrove D, Holder J, Kilkenny J D, Lumbard A, Montesanti R, Palmer N E, Piston K, Stone G, Thao M, Vern R, Zacharias R, Landen O L, Tommasini R, Bradley D K, Bell P M
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
General Atomics, San Diego, California 92121, USA.
Rev Sci Instrum. 2014 Nov;85(11):11D623. doi: 10.1063/1.4891712.
Recently developed diagnostic techniques at LLNL require recording backlit images of extremely dense imploded plasmas using hard x-rays, and demand the detector to be sensitive to photons with energies higher than 50 keV [R. Tommasini et al., Phys. Phys. Plasmas 18, 056309 (2011); G. N. Hall et al., "AXIS: An instrument for imaging Compton radiographs using ARC on the NIF," Rev. Sci. Instrum. (these proceedings)]. To increase the sensitivity in the high energy region, we propose to use a combination of two MCPs. The first MCP is operated in a low gain regime and works as a thick photocathode, and the second MCP works as a high gain electron multiplier. We tested the concept of this dual MCP configuration and succeeded in obtaining a detective quantum efficiency of 4.5% for 59 keV x-rays, 3 times larger than with a single plate of the thickness typically used in NIF framing cameras.
劳伦斯利弗莫尔国家实验室（LLNL）最近开发的诊断技术需要使用硬x射线记录极其致密的内爆等离子体的背光照相图像，并且要求探测器对能量高于50 keV的光子敏感[R. 托马西尼等人，《物理等离子体》18, 056309 (2011)；G. N. 霍尔等人，“AXIS：一种用于在国家点火装置（NIF）上使用ARC成像康普顿射线照相的仪器”，《科学仪器评论》（本会议论文集）]。为了提高在高能区域的灵敏度，我们建议使用两个微通道板（MCP）的组合。第一个MCP在低增益模式下运行，用作厚光电阴极，第二个MCP用作高增益电子倍增器。我们测试了这种双MCP配置的概念，并成功获得了59 keV x射线4.5%的探测量子效率，比国家点火装置（NIF）分幅相机通常使用的单块板厚的探测量子效率大3倍。
