Dynamic Focusing to Suppress Emittance Transfer in Crab-Crossing Flat Beam Collisions

Area of Science:

• Particle accelerator physics
• High-energy physics

Background:

• Flat hadron beams promise an order of magnitude increase in peak luminosity for particle colliders.
• Demonstrating and maintaining flat beam conditions has remained a significant experimental challenge.

Purpose of the Study:

• To identify and characterize a novel mechanism limiting flat hadron beam stability.
• To investigate the impact of machine fluctuations on beam emittance.
• To propose a viable solution for robust flat-beam operation in future colliders.

Main Methods:

• Analysis of synchrobetatron resonances driven by machine fluctuations.
• Emittance transfer modeling under realistic noise conditions.
• Simulation using Electron-Ion Collider (EIC) parameters.
• Development and testing of a dynamic focusing scheme.

Main Results:

• A new hourglass-induced synchrobetatron resonance mechanism was identified.
• This resonance, coupled with machine noise, drives emittance transfer and degrades the flat-beam condition.
• Stringent tolerances on machine noise were established for the EIC.
• A dynamic focusing scheme effectively suppresses the resonance and relaxes noise constraints.

Conclusions:

• The identified resonance poses a critical limitation for operational flat hadron beams.
• Dynamic focusing using sextupoles and crab cavities offers a practical solution.
• This approach enables robust flat-beam collisions in future lepton-hadron colliders.