[time-nuts] Choice of MASER gas

[Mark Kahrs]

John Miles brought up an interesting question that got lost in the
discussion of high vacuum systems: what about the choice of gas?

Besides H, there is a dual Xe/He system detailed in:

http://www.cfa.harvard.edu/Walsworth/pdf/Bear%20thesis.pdf

And, as mentioned before, Harvard has built Rb masers:

http://cfa-www.harvard.edu/~dphil/work/coat.pdf<http://cfa-www.harvard.edu/%7Edphil/work/coat.pdf>
<http://cfa-www.harvard.edu/%7Edphil/work/coat.pdf>

And John mentioned HN3 masers (advantage: you would be able to smell the
leak!).