| 单词 | 平均寿命 |
| 释义 | 〔tau〕An elementary particle of the lepton family, having a mass about 3,490 times that of the electron, a negative electric charge, and a mean lifetime of 3×10-13 seconds. See table at subatomic particle τ介子：一种轻子族群中的基本粒子，其质量约为电子的3,490倍，带有一个负电荷，平均寿命为3×10-13秒 参见 subatomic particle〔pion〕A semistable meson produced either in a neutral form with a mass 264 times that of an electron and a mean lifetime of 8.4 × 10-17 second or in a positively charged form with a mass 273 times that of an electron and a mean lifetime of 2.6 × 10 -8 second. Also called pi meson See table at subatomic particle π介子：一种半稳定介子，或者以一种质量比电子重264倍的中性形式生成，其平均寿命期为8.4×10-17秒；或者以一种质量比电子重273倍的正电极形式生成，其平均寿命期为2.6×10 -8秒 也作 pi meson 参见 subatomic particle〔antiparticle〕A subatomic particle, such as a positron, an antiproton, or an antineutron, having the same mass, average lifetime, spin, magnitude of magnetic moment, and magnitude of electric charge as the particle to which it corresponds but having the opposite sign of electric charge, opposite intrinsic parity, and opposite direction of magnetic moment. See table at subatomic particle 反粒子：一种亚原子粒子，如正电子、反质子或反中子，与它相对应的粒子有相同的质量、平均寿命、核量子数、磁矩量和电荷量，但具有相反的电荷标志、内在均势和磁矩方向 参见 subatomic particle〔muon〕An elementary particle in the lepton family (not a meson), having a mass 209 times that of the electron, a negative electric charge, and a mean lifetime of 2.2 × 10-6 second. Also called mu meson See table at subatomic particle 介子：轻子族中的一种基本微粒（非介子），其质量为电子的209倍，是一种负电荷，平均寿命为2.2×10-6秒 也作 mu meson 参见 subatomic particle〔neutron〕An electrically neutral subatomic particle in the baryon family, having a mass 1,839 times that of the electron, stable when bound in an atomic nucleus, and having a mean lifetime of approximately 1.0×103 seconds as a free particle. It and the proton form nearly the entire mass of atomic nuclei. See table at subatomic particle 中子：重子家族中电中性的亚原子粒子，是电子体积的1,839倍，作为自由粒子撞击原子核时保持稳定，平均寿命大约 1.0×103。它和质子几乎构成了整个原子核的质量 参见 subatomic particle |
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