Development of a simulation for measuring neutron electric dipole moment
Development of a simulation for measuring neutron electric dipole moment
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开发用于测量中子电偶极矩的模拟
DOI：
10.1088/1742-6596/528/1/012031
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Yoshichika SEKI
中科院分区：
文献类型：
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作者：
Ryo KATAYAMA;Kenji MISHIMA;Satoru YAMASHITA;Dai SAKURAI;Masaaki KITAGUCHI;Tamaki YOSHIOKA;Yoshichika SEKI
中子电偶极矩（nEDM）对标准模型之外的新物理非常敏感，可能被证明是CP违反的新来源。世界范围内正在计划进行几项高精度测量实验。在均匀电场和磁场作用下，用贮存瓶中的超冷中子（UCN）自旋进动来测量nEDM。在nEDM测量中，系统的不确定度是由于ucn的运动、测量系统的几何形状以及不均匀的电场和磁场。因此，有必要定量地了解这些影响，以减少它们。Geant4UCN是一个理想的仿真框架，因为它可以计算UCN轨迹，评估自旋进动在任意电场和磁场下的时间演变，并灵活地定义存储几何形状。我们检查了Geant4UCN计算自旋进动的准确性。我们发现，由于舍入误差，在假设电场和磁场强度分别为10 kV/cm和1 μT，存储时间为100 s的情况下，无法准确地模拟nEDM实验。在本文中，我们报告了其差异并描述了解决方案。
The neutron electric dipole moment (nEDM) is sensitive to new physics beyond the standard model and could prove to be a new source of CP violation. Several experiments are being planned worldwide for its high-precision measurement. The nEDM is measured as the ultracold neutron (UCN) spin precession in a storage bottle under homogeneous electric and magnetic fields. In nEDM measurement, the systematic uncertainties are due to the motion of the UCNs, the geometry of the measurement system, and inhomogeneous electric and magnetic fields. Therefore, it is essential to quantitatively understand these effects in order to reduce them. Geant4UCN is an ideal simulation framework because it can compute the UCN trajectory, evaluate the time evolution of the spin precession due to arbitrary electric and magnetic fields, and define the storage geometry flexibly. We checked how accurately Geant4UCN can calculate the spin precession. We found that because of rounding errors, it cannot simulate it accurately enough for nEDM experiments, assuming homogeneous electric and magnetic fields with strengths of 10 kV/cm and 1 μT, respectively, and 100 s of storage. In this paper, we report on its discrepancies and describe a solution.