We study the full charge counting statistics of a charge pump based on a
nearly open single electron transistor. The problem is mapped onto an exactly
soluble problem of a g=1/2 non-equilibrium Luttinger liquid with an impurity.
We obtain an analytic expression for the generating function of the transmitted
charge for an arbitrary pumping strength. Even though this model contains
fractionally charged excitations only integer transmitted charges can be
observed during finite observation times.Comment: 4 pages, 1 figur