The calculation of the pressure distribution in the vacuum systems of particle detectors for the colliding beams

A method, allowing one to obtain the analytic expressions for the calculation of the pressure distribution in complex vacuum systems consisting of a series of cylindrical and tapered tubes from different vacuum materials, for example, high vacuum systems of particle detectors for an accelerating complex, with consideration of the thermal and stimulated outgassing, is presented. A method of estimating the ion stimulated desorption influence upon the pressure stability in such vacuum systems and its contribution to the total pressure distribution is proposed. Very simple computer programs, based on this method, allow us to obtain and analyze the pressure distribution in the same complex vacuum systems depending on different vacuum parameters.