Fits to consec data In what follows the black line shows the mean and the rms of the double gaussian fit The green line (usually too small to be visible) shows the error on the fit in x and y I looked back through the data from all shots Only 4 gave clean fits The effort to take a clean shot just before changing position on the sensor paid off – see shot 35 Unfortunately no high intensity data was useable – mostly because the timing was off (beam came too early) and for the other shots we were not “lucky” The following slides show pictures of all the “good fits”, with the 2d histogram with the fit superimposed following the colour plot

Shot 38: Example of a “failed fit”

Shot 3 (picture is rotated to fit it on the slide) X direction Y direction

Shot 5

Shot 35_4

Shot 36

Beam spot positions and widths in x and y (statistical error is always very small) Shot 3 – x: – Y: Shot 5 – x: – y: Shot 35_4 – x: – y: Shot 36 (after the beam was moved to the new sensor position) – x: – y: The widths are pretty consistent The centroid moves by ~mm

Comparison with beam screen image data