Research Progress of UHV/XHV Measurement Mechanism Based on Cold Atoms

With the development of laser-cooling and trapping technology of atoms, the new method of accurately measuring the ultra-high/extreme-high vacuum(UHV/XHV) is being studied in depth based on the loss-rate of ultra-cold atoms colliding with the background gas in the magnetic traps.This method connects the macroscopic physical quantities with microscopic parameters, and can realize precise measurement of gas density and accurate inversion of vacuum pressure.However, the detailed analysis of non-ideal loss mechanism of collisional loss process and some other additional effects on the measurement was lacked, which limited the progress of this technology.This paper summarized the determination methods of key parameters of vacuum pressure measurement process of cold atoms and then analyzed their advantages and disadvantages, in view of additional losses that affect the measurement uncertainty, the physical or mathematical models were classified and discussed on the basis of relevant research, and the corresponding measures that can be taken to reduce the measurement uncertainty were analyzed.Finally, the UHV/XHV measurement technology of cold atoms was summarized and prospected from the aspects of key parameters determination and the other additional losses analysis.