Heshbeam-a program with a graphical user interface for calculation of the luminosity spectrum and the differential luminosity

The paper presents a program with a Graphical User Interface for solving the luminosity spectrum and the differential luminosity. Instead of using the particles-in-cells method, the code is based on analytical solutions and experimental results. The user creates with the GUI an input data file, which contains only a few numbers of parameters, such as the beam size at the IP, the number of particles and the center-of-mass energy. The beam, with a round or elliptical cross-section, is described by a uniform or a gaussian density function in transverse and longitudinal direction. In all cases the program makes use of the analytical solutions for the beam-beam energy loss, the deflection angle, the luminosity spectrum and the differential luminosity. The results for several linear collider designs and different disruption numbers are obtained and compared with other numerical solutions. The numerical examples demonstrate clearly the accuracy of this method.