First Positrons in the FCC-ee Positron Production Experiment (P3) at SwissFEL

For the Future Circular Collider (FCC-ee), particular attention is drawn to the crucial role of the positron source. The almost universal usage of target-based production schemes combined with conventional capture technology has led to poor transmission efficiencies. This long-standing difficulty to handle the extreme e+ transverse emittance and energy spread has been a major limitation for future, high luminosity lepton collider designs. 

The PSI Positron Production (P-cubed or P3 ) experiment, framed in the FCC-ee study, is a demonstrator for a e+ capture system with potential to improve the state-of-the-art e+ yield by an order of magnitude. The experiment’s commissioning was started in July and on July 28 the above integrated positron charge was recorded, with model predictions on the left, and recorded data on the right.

These first results confirm the predictions of record-breaking positron-yield, leading to lower-energy impinging electron beams and a more robust target design for the FCC-ee injector.

Cumulative positron charge simulated (left) and measured (right).
P3 Experiment installed in a SwissFEL bunker.
P3 capture solenoid using REBCO no-insulation coil technology.