Analytical evaluation of Doppler functions arising from resonance effects in nuclear processes

We present a new method for the analytical evaluation of Doppler function arising from resonance effects in nuclear processes. The method yields stable results in nuclear physics field avoiding complicated analytic approximations. Explicit formulas for the Doppler function are developed in terms of series of binomial coefficients and incomplete functions. The obtained results permit a very fast evaluation of Doppler function with a degree of accuracy higher than the one required for nuclear resonance absorption. Implementation in a computer program of our approach is described.