单粒子翻转英文缩写SEU（Single-Event Upsets），航天电子学术语，原因是在空间环境下存在着大量高能带电粒子，计算机中的CMOS电子元器件受到地球磁场、宇宙射线等照射，引起电位状态的跳变，“0”变成“1”，或者“1”变成“0”，但一般不会造成器件的物理性损伤。

单粒子翻转指标用单粒子翻转率来描述，单粒子翻转率是器件每天每位发生单粒子翻转的概率，计算质子单粒子翻转率的一般性公式：

其中：为阈值能量，单位MeV；为质子单粒子翻转截面积，单位；为质子微分流量。

A single event upset (SEU) is a change of state caused by one single ionizing particle (ions, electrons, photons...) striking a sensitive node in a micro-electronic device, such as in a microprocessor, semiconductor memory, or power transistors. The state change is a result of the free charge created by ionization in or close to an important node of a logic element (e.g. memory "bit"). The error in device output or operation caused as a result of the strike is called an SEU or a soft error.