Beam losses along the ESS LINAC due to nonlinear effects - A Statistical review

Sammanfattning: In this project, a comprehensive statistical review is done regarding beam distribution evolution and losses of protons in the ESS LINAC. It aims to clarify some unanswered questions regarding the change in the distribution as it evolves through the LINAC and how sudden changes can effect the losses of protons downstream. The correlation between the sub phase-spaces were removed to be able to study the nonlinear forces acting on the distribution. Several statistical tools were used to analyse these distributions and visualize them in a comprehensive manner. Furthermore, this report aims to give an overview of the maximum losses that one may expect in the current lattice configuration in the ESS LINAC. An EVT (Extreme Value Theory) approach was used to model these extreme losses to highlight extreme scenarios in the LINAC. Many interesting features arise regarding the distribution evolution which can be confirmed in theory and the maximum losses could be regarded as within the limit set by the ESS design report. The results illustrates that changes in the distribution can be found with the KS-test and can act complementary to the tools used by the physicists today, with a little refinements. Furthermore, the GMM may indicate that the distributions are multimodal, thus opening the questions around the interpretation of the moments of the distributions and their relation to the tools used for analysis. The EVT approach showed that no concern is needed regarding the exceedances of the proposed highest limit of losses, 1 W/m. In conclusion, the report highlights statistical tools for beam monitoring and further research in this subject may be of scientific interest.