A Method for Eliminating the Wall Shift in the Atomic Hydrogen Maser

Abstract

The wall shift of the hydrogen maser depends on the collision rate and the average phase shift per collision of the atoms in the storage bulb. By operating at the temperature where the average phase shift per collision is zero it is possible to remove the wall shift. The determination of this temperature is made by measuring the wall shift as a function of temperature for two similarly coated bulbs offering different collision rates to the stored atoms. The intercept of the wall shift vs. temperature curve for the two bulbs-occurs at the zero phase shift per collision temperature. To eliminate the possible differences in wall coatings the use of a flexible storage bulb is recommended. An experimental example of the technique is given using two separate bulbs. The data is in good agreement with a previous measurement of the unperturbed hydrogen hyperfine frequency by H. Hellwig et al.