Study of beam profile measurement at interaction point in international linear collider

At the international linear collider, measurement of the beam profile at the interaction point is a key issue to achieve high luminosity. We report a simulation study on a new beam profile monitor, called the pair monitor, which uses the hit distribution of the electron–positron pairs generated at the interaction point. We obtained measurement accuracies of 5.1%, 10.0%, and 4.0% for the horizontal ( σ x ) , vertical ( σ y ) , and longitudinal beam sizes ( σ z ) , respectively, for 50 bunch crossings.