The Space Variable Object Monitor (SVOM) is a forthcoming Chinese - French astrophysics space mission dedicated to the study of Gamma-ray bursts and high-energy transients. ECLAIRs, a wide-field hard X-ray coded mask imager, is the leading instrument for the transient detection and their first localisation. The sensitivity of such instruments is usually limited by the background, either of instrumental or astrophysical origin. Detailed estimations of the background are obtained by simulating the interaction of particles with the matter using, in the present case, the GEANT4 Monte-Carlo toolkit. However, this is a time consuming process, especially when it is needed to carry out all possible geometrical and orbital configurations. Instead, we present a much faster method that allows computing the background in either a static or dynamic (time dependent) way. The method is based on the preliminary calculation of a large particle database using the GEANT4 toolkit followed by a selection process based on the incoming direction and energy of the particles. This approach is as accurate as direct Monte-Carlo methods, while it reduces the computation time by a factor of $10^3 - 10^4$ for our application. We apply this method to compute the SVOM/ECLAIRs dynamic background.

中文翻译：

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SVOM/ECLAIRs 动态背景的模拟：一种快速、准确和通用的宽视场硬 X 射线仪器方法

空间可变物体监测器（SVOM）是即将到来的中法天体物理学太空任务，致力于研究伽马射线暴和高能瞬变。ECLAIRs 是一种宽视场硬 X 射线编码掩模成像仪，是瞬态检测及其首次定位的领先仪器。这种仪器的灵敏度通常受仪器或天体物理起源的背景的限制。背景的详细估计是通过使用 GEANT4 Monte-Carlo 工具包模拟粒子与物质的相互作用来获得的。然而，这是一个耗时的过程，尤其是当需要执行所有可能的几何和轨道配置​​时。反而，我们提出了一种更快的方法，允许以静态或动态（时间相关）方式计算背景。该方法基于使用 GEANT4 工具包对大型粒子数据库进行初步计算，然后根据粒子的传入方向和能量进行选择过程。这种方法与直接蒙特卡罗方法一样准确，同时它为我们的应用程序将计算时间减少了 $10^3 - 10^4$。我们应用这种方法来计算 SVOM/ECLAIRs 动态背景。虽然它为我们的应用程序减少了 $10^3 - 10^4$ 的计算时间。我们应用这种方法来计算 SVOM/ECLAIRs 动态背景。虽然它为我们的应用程序减少了 $10^3 - 10^4$ 的计算时间。我们应用这种方法来计算 SVOM/ECLAIRs 动态背景。