Weighted statistics for unevenly spaced SEM-grids on Linac4 line.

A beam profile may be measured in several ways [1]. Independent of the method chosen, the agreement between the simulation and measurements need to be accurate enough to minimize errors. In order to improve this comparison, we introduce new beam size estimators based in weighted statistics. We show that, for the situations in which the SEM-grid wires are unevenly spaced, the weighted standard deviation reveal us as an efficient alternative for determine the beam rms size. These theoretical predictions, implemented in the java application Linac4 SEM-grids 1.0, are than compared with measurements of the Linac4 line showing the pros and cons together with Gaussian fittings.