On Mon, 29 Nov 2021 13:23:33 +0000 "Poul-Henning Kamp" <p...@phk.freebsd.dk> wrote:
> The resonance we measure is not the real one, but one affected by > the doppler-shift of the atoms speed, ie: velocity without sign, > in the direction of interrogation. Modern, laser based Rb standards can measure doppler-free by selecting only those atoms that are in rest or only move laterally to the laser beam. But, as far as I know, there is no commercial product available that does that. > I belive the primary source of drift in Rb's are adsorption and > absorption of Rb molecules onto and into the glass itself. This > causes a drop of gas pressure, which changes the collision dynamics > for the remaining Rb gas, which affects their velocity distribution, > which again moves the "appearant resonance" we measure. Largest sources of uncertainty for an Rb are: * Temperature (affects Rb density and buffer gas pressure) * Atmospheric pressure (affects pressure inside the glass cell) * Light and microwave intensity variation (shifts the electron energies) * Helium absorption (changes buffer gas compostion) I have not seen any measurement of Rb absorption into glass and its effect, so I cannot comment on that. Attila Kinali -- The driving force behind research is the question: "Why?" There are things we don't understand and things we always wonder about. And that's why we do research. -- Kobayashi Makoto _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.