Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Quantum Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Rev Sci Instrum. 2022 Dec 1;93(12):121101. doi: 10.1063/5.0120500.
We describe the cold-atom vacuum standards (CAVS) under development at the National Institute of Standards and Technology (NIST). The CAVS measures pressure in the ultra-high and extreme-high vacuum regimes by measuring the loss rate of sub-millikelvin sensor atoms from a magnetic trap. Ab initio quantum scattering calculations of cross sections and rate coefficients relate the density of background gas molecules or atoms to the loss rate of ultra-cold sensor atoms. The resulting measurement of pressure through the ideal gas law is traceable to the second and the kelvin, making it a primary realization of the pascal. At NIST, two versions of the CAVS have been constructed: a laboratory standard used to achieve the lowest possible uncertainties and pressures, and a portable version that is a potential replacement for the Bayard-Alpert ionization gauge. Both types of CAVSs are connected to a combined extreme-high vacuum flowmeter and dynamic expansion system to enable sensing of a known pressure of gas. In the near future, we anticipate being able to compare the laboratory scale CAVS, the portable CAVS, and the flowmeter/dynamic expansion system to validate the operation of the CAVS as both a standard and vacuum gauge.
我们介绍了美国国家标准与技术研究院（NIST）正在开发的冷原子真空标准（CAVS）。CAVS 通过测量磁阱中亚毫开尔文传感器原子的损失率来测量超高真空和极高空之间的压力。根据基本的量子散射截面和速率系数计算，背景气体分子或原子的密度与超冷传感器原子的损失率有关。通过理想气体定律进行的压力测量可追溯到第二和开尔文，这使其成为帕斯卡的主要实现。在 NIST，已经构建了两种 CAVS：一种是实验室标准，用于实现尽可能低的不确定度和压力，另一种是便携式标准，可能替代巴雅尔-阿尔珀特电离计。这两种类型的 CAVS 都与一个组合的超高真空流量计和动态膨胀系统相连，以便能够感测到已知的气体压力。在不久的将来，我们预计能够对实验室规模的 CAVS、便携式 CAVS 和流量计/动态膨胀系统进行比较，以验证 CAVS 作为标准和真空计的运行情况。
