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Journal of Astrophysics & Aerospace Technology | ISSN: 2329-6542 | Volume 6
Atomic and Nuclear Physics
4
th
International Conference on
October 26-27, 2018 | Boston, USA
Absolute pressure standard using cold atoms
James L Booth
British Columbia Institute of Technology, Canada
P
article detection in high and ultra-high vacuum environments below 10
-6
torr is essential for beam flux measurements and ambient
pressure determinations. Electron impact ionization and subsequent detection of the ions is, at present, the most widespread and
sensitive method and it constitutes the functional basis for ionization vacuum gauges. These gauges suffer from the limitation that
they lose their calibration when the ion production or collection efficiencies change because the sensor electrodes change position
and the internal electric fields are altered or when the gain of the ion current multiplier is modified due to surface contamination or
degradation. By contrast, a stationary or slowly moving atom, such as can be prepared by laser cooling, is an ideal particle flux sensor.
In brief, the passage of a particle through the collision cross section of the sensor atom is detected by the momentum transferred to the
quasi-stationary sensor atom. The incident particle flux is determined from the measured single-particle collision rate divided by the
total cross section. The latter quantity can be computed from knowledge of the interaction potentials and the former is a measurement
of time. The main advantage of this detection mechanism is that it is not subject to sensor degradation or calibration drift since the
sensor atoms are always the same and the interaction between the sensor atom and the detected particle is an immutable law of
nature. These features and the direct link between particle flux and time makes this method a unique candidate for the realization of
a primary pressure standard at and below 10
-6
torr.
James_Booth@bcit.caJ Astrophys Aerospace Technol 2018, Volume 6
DOI: 10.4172/2329-6542-C3-024