UBC Theses and Dissertations
Progress towards a portable cold-atom pressure standard Waldock, Perrin A. Z.
All existing pressure standards (classical and quantum-based) are large apparatuses - typically, the size of a van or larger. In this thesis, we report on the progress towards building a portable version of a cold-atom based pressure standard which can easily transported by a van instead. Specifically, we discuss - the flexible laser design that can produce 780 nm pump light anywhere in a 26 GHz range and repump light anywhere in a +/- 6.8 GHz range within <1 MHz with no realignment. - the magnetic field coils that can produce gradients in excess of 400 G/cm without changing temperature (provided that >14 mL/s of 10 C to 15 C water is available. - the low-outgassing vacuum chamber that can supply rubidium for measurement while minimizing contamination in the chamber under test. - preliminary results characterizing the performance of its rubidium source and magneto-optical trap. - future plans for the apparatus. This pressure standard leverages the linear relationship between the pressure of a vacuum chamber and loss rate of atoms from a magnetic trap in that chamber. Using the universality of loss rates with respect to trap depth, we can use this apparatus to measure the total collision cross section between the trapped rubidium and any species of collision partner. We can also take advantage of the flexible design of its laser system to quickly alternate measurements between ⁸⁵Rb and ⁸⁷Rb to confirm the universal behaviour of both isotopes. We plan to take the apparatus to Physikalisch-Technische Bundesanstalt in the coming months to compare the cold-atom based standard against their orifice flow standard.
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