Status of Guinea-Pig program development —— Guy Le Meur
A new feature in the C++ version of the Guinea-Pig program, guineapig++, was presented in this talk: automatic grid sizing. A grid is used in Guinea-Pig to compute the electric fields from the Poisson equation in a discretised way. For reliable and efficient calculations when Guinea-Pig is used to compute beam-beam observables important for the intra-train feedback system, the size of this grid must take into account in an adaptive way the varying offsets and sizes of the colliding bunches at the IP. This can be achieved through a partly empirically tuned algorithm based on calculating the center of mass disruption angle. Some technical testing was done but a full evaluation remains needed for a full assessment in the context of large-scale ILC luminosity performance studies. A few other improvements to the guineapig++ output file were also implemented to simplify and clarify the information provided.
Guinea-Pig program computing time optimization — François Touze
Guinea-Pig cuts the bunches into slices which are moved longitudinally and made to interact when they are in the same transverse plane. When the computation of secondary pairs is included, the generation of these pairs largely dominates the computing time. Attempts to distribute the calculation on parallel CPUs allows to speed up the calculation by about a factor 2 (for 4 CPUs). Further possible reductions of the computing time are also considered by optimizing the pair generator itself, including investigating the minimum number of generations needed for adequate statistical precision, better sampling of the kinematical phase-space for a more efficient application of the veto method, and computing the full kinematics of generated pairs only once.
There are minutes attached to this event.
Show them.
