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Report of the SC working group. 19.02.2014 SC working group. Miscellaneous. Elena and Hannes are replacing Frank during his absence for chairing the SC meeting and writing the minutes Series of “Educational talks”
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Report of the SC working group 19.02.2014 SC working group
Miscellaneous • Elena and Hannes are replacing Frank during his absence for chairing the SC meeting and writing the minutes • Series of “Educational talks” • Tunes modulation in a space charge dominated beam: the particles behavior in the "necktie” (Vincenzo) • Phase advance and tunes in 5D&6D (Frank) • Symplectic integrators (Adrian) • Computational resources • original idea of Bernd to integrate special machines with 48 cores into the LSF cluster for the SC simulations is not feasible • Instead we need to request a doubling of our computer resources with a lead time of 2-3 weeks before the peak load of simulations will be needed • Preparation of SC collaboration meeting in May 2014 well on track • draft program is finished; many collaborators already confirmed their participation
Recent highlights of ongoing studies • bug in PTC-ORBIT causing the spikes in PSB simulations • resolved by the PSB team with the help of Harry • related to the longitudinal phase space treatment of PTC (stable phase) and the 2.5D space charge module of ORBIT. • A fix of the problem was prepared and the changes to the code have been agreed by the ORBIT developers new version of ORBIT-PTC compiled and ready for use • Continuation of tune evolution studies for particles under the SC force (Vincenzo) • Started to discuss the latest results in the last SC meeting • Comparison of the phase advance per turn (‘instantaneous tune’) with the average phase advance along a full synchrotron period
MADX frozen space charge (Frank) • Scalar speed optimized - HR • Lost particles were not taken care of - KwangminBNL • Non-reproducible results found at CERN - FS & HR; Problem has been a critical sum. Remedies: • Take summing out of OPENMP (cost to speed-up remains small) - KwangminBNL • Optimize summation à la Kahan summation algorithm – FS • Critical failure due to subroutine call within OPENMP loop • solved by taking out the OPENMP - FS & Kwangmin • loss in speed-up small. • Speed-up of TWISS checked but not efficient – Kwangmin • Introducing error function from SixTrack - GA Erskine, E. Mcintosh & FS • Speed-up about 25%. • Final checking of speed-up and code consistency at CERN - HR, E. Mcintosh & FS • New revision of manual; writing up the OPENMP experience • Integration into main MAD-X release - FS & Laurent Deniau
Work programs and list of MDs for the PSB, PS and SPS as can be found on the SC website …
PS • Present focus • studies of 4th order resonance (Raymond) • Simulations with MADX frozen space charge (Frank and Raymond) • Detailed list of MDs planned for 2014 in preparation