Collisional frequency shifts and line broadening in the cryogenic deuterium maser

We study the spin-exchange frequency shifts and line broadening of the deuterium maser in the temperature range from 0 to 10 K. We consider both a version operating on the {β}-{ε} transition at B=3.0 {μ}T and one operating on the {β}-{δ} transition at B=3.9 mT. For the first transition, a comparison is made with our earlier results based on the degenerate-internal-states approximation and its first-order corrections [E. Tiesinga, H. T. C. Stoof, B. J. Verhaar, and S. B. Crampton, Physica B 165&166, 19 (1990)]. We find cusp structures due to channel thresholds and also resonance structures, both of which disappear almost completely after thermal averaging in the temperature range considered.