MD3287: Luminosity scans with waist shifts

This note reports on the first measurements of the beam waist displacements in the LHC using luminosity scans. The experiment consisted on applying an optics knob designed to displace the betatron waist and to measure the response of the luminosity, in order to find its maximum. One knob per beam was designed beforehand to displace the vertical betatron waist of Interaction Point 1 (IP1). Two scans were performed for each knob. During the MD it was noticed that the knobs were largely affecting the tunes and therefore the second scan of each knob was performed correcting the tune between steps. After processing, the beam waist position was determined with better precision than that of K-modulation.