Measurement of bunch length in LEP

Bunch lengths under various beam conditions were measured with the button electrode. From the data it may be concluded that this system has a quadratic error of ~ 15 mm2. However, it is not entirely constant over the range of bunch lengths and this may be attributed to deviations from the ideal Gaussian profile that is assumed. A cross-check measurement was also performed to create a link to the measurements with the streak camera done in an earlier MD.