Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics.
Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics.
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DOI：
10.1038/srep41511
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发表时间：
2017-02-03
影响因子：
4.6
通讯作者：
Yoshikawa K
中科院分区：
文献类型：
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作者：
Tanimori T;Mizumura Y;Takada A;Miyamoto S;Takemura T;Kishimoto T;Komura S;Kubo H;Kurosawa S;Matsuoka Y;Miuchi K;Mizumoto T;Nakamasu Y;Nakamura K;Parker JD;Sawano T;Sonoda S;Tomono D;Yoshikawa K
自从核γ射线被发现以来，其成像一直局限于伪成像，如康普顿照相机（CC）和编码掩模。伪成像不保持物理信息（强度或光学中的亮度）沿着射线，因此只能对明亮物体进行定性成像。为了实现定量成像，实现几何光学的相机是必不可少的，对于核MeV伽马，这只有通过完全重建康普顿过程才有可能。最近，我们发现，“电子跟踪康普顿相机”（ETCC）提供了一个定义良好的点扩散函数（PSF）。入射伽马的信息被保持沿着具有点扩散函数的射线，这相当于几何光学。在这里，我们提出了一个成像光谱测量与ETCC。我们的研究结果突出了固有的困难与CC在执行准确的成像，并表明，ETCC克服了这个问题。成像能力还有助于ETCC在没有屏蔽结构的情况下将噪声水平显著抑制约3个数量级。此外，完全重建的康普顿过程与ETCC提供光谱的康普顿边缘。这些结果标志着第一次正确的核伽玛成像的基础上真正的几何光学。
Since the discovery of nuclear gamma-rays, its imaging has been limited to pseudo imaging, such as Compton Camera (CC) and coded mask. Pseudo imaging does not keep physical information (intensity, or brightness in Optics) along a ray, and thus is capable of no more than qualitative imaging of bright objects. To attain quantitative imaging, cameras that realize geometrical optics is essential, which would be, for nuclear MeV gammas, only possible via complete reconstruction of the Compton process. Recently we have revealed that “Electron Tracking Compton Camera” (ETCC) provides a well-defined Point Spread Function (PSF). The information of an incoming gamma is kept along a ray with the PSF and that is equivalent to geometrical optics. Here we present an imaging-spectroscopic measurement with the ETCC. Our results highlight the intrinsic difficulty with CCs in performing accurate imaging, and show that the ETCC surmounts this problem. The imaging capability also helps the ETCC suppress the noise level dramatically by ~3 orders of magnitude without a shielding structure. Furthermore, full reconstruction of Compton process with the ETCC provides spectra free of Compton edges. These results mark the first proper imaging of nuclear gammas based on the genuine geometrical optics.