First direct observations of gear-changing in a collider

In this work we perform the first demonstration of gear-changing in a real world collider. Gear-changing refers to a collision scheme where each ring of a collider stores a different harmonic number of bunches. These bunches are kept synchronized using different velocities. Such a system has been theorized, but has now been demonstrated using the Double ElectroStatic Ion Ring ExpEriment (DESIREE) in Stockholm Sweden. The experiment was able to demonstrate a gear-changing system, with both four on three bunches and five on four bunches. We determined a measurable parameter that shows a gear-changing system out to 37500 turns of the slow beam (1 s). We were also able to detect a measurable longitudinal beam–beam interaction. We developed insights into how to control this type of system, opening up new possibilities, and showing that DESIREE can be used for gear-changing research.