IEEE Trans Ultrason Ferroelectr Freq Control. 2013 Feb;60(2):428-31. doi: 10.1109/TUFFC.2013.2580.
The SI unit of mass, the kilogram, is defined by a single artifact, the International Prototype Kilogram. This artifact, the primary mass standard, suffers from long-term instabilities that are neither well understood nor easily monitored. A secondary mass standard consisting of a 1-kg quartz resonator in ultrahigh vacuum is proposed. The frequency stability of such a resonator is likely to be far higher than the mass stability of the primary mass standard. Moreover, the resonator would provide a link to the SI time-interval unit. When compared with a laboratory-grade atomic frequency standard or GPS time, the frequency of the resonator could be monitored, on a continuous basis, with 10(-15) precision in only a few days of averaging. It could also be coordinated, worldwide, with other resonator mass standards without the need to transport the standards.
质量的 SI 单位，千克，由一个单一的人工制品定义，即国际原型千克。这个人工制品，主要的质量标准，长期以来存在不稳定性，既没有很好的理解，也不容易监测。建议采用由超高真空中的 1 公斤石英谐振器组成的二级质量标准。这种谐振器的频率稳定性很可能远远高于主要质量标准的质量稳定性。此外，谐振器将为 SI 时间间隔单位提供联系。与实验室级别的原子频率标准或 GPS 时间相比，谐振器的频率可以在短短几天的平均时间内以 10(-15)的精度进行连续监测。它也可以在全球范围内与其他谐振器质量标准进行协调，而无需运输标准。
