Measurement of the Hydrogen Spin-Exchange Cross Section with the Hydrogen Maser

The oscillation characteristics of the hydrogen maser under the influence of hydrogen-hydrogen spin-exchange collisions are described and discussed. Using experimental data from an oscillating hydrogen maser, the hydrogen spin-exchange cross section is calculated. A value of $\sigma =2.65\mathrm{}\times {10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ at room temperature is obtained and compared with previously published values. A brief discussion on a possible increase of the maser output power is given.