Performance improvement of X-ray CCDs by applying a magnetic field

X射线CCDs现在被认为是X射线望远镜的标准焦平面探测器。其中，应用最广泛的是深耗尽层背面照明的CCDs。然而，由于背表面电场较弱，电荷云倾向于大范围扩展，因此能量分辨率较差，带电粒子本底较高。因此，我们试图通过施加外加磁场来抑制电荷扩展，从而提高CCD的性能。我们发现，只有0.3T的磁场才足以引起沿水平方向电荷分裂的系统差异。此外，尽管显著性较低，但我们发现能量分辨率随着磁场的增加而略有提高。这些结果首次表明，我们可以通过施加外加磁场来控制硅中电荷的运动，从而提高X射线CCDS的性能。

X-ray CCDs are now regarded as a standard focal plane detector of X-ray telescopes. Among them, backside illuminated CCDs with a deep depletion layer are being most widely used. However, because the electric field is weak at the back surface and the charge clouds tend to extend largely, they have poorer energy resolution and higher charged-particle background. Thus, we tried to suppress the charge extension by applying an external magnetic field and to improve the CCD's performance. We found that only a magnetic field of 0.3T is enough to cause systematic difference in charge splitting along the horizontal direction. Furthermore, although significance was low, we found energy resolution to improve slightly with the magnetic field. These results show for the first time that we can control the movement of charges in silicon and improve the performance of X-ray CCDs by applying an external magnetic field.