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Lower-Frequency RF Phase Rotation Techniques for Both Muon Signs. Stephen Brooks, RAL s.j.brooks@rl.ac.uk Matthew McCullough, University College, Oxford matthew.mccullough@univ.ox.ac.uk. Low-Frequency Phase Rotation. The UKNF phase rotator evolved from the CERN design
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Lower-Frequency RF Phase Rotation Techniques for Both Muon Signs Stephen Brooks, RAL s.j.brooks@rl.ac.uk Matthew McCullough, University College, Oxford matthew.mccullough@univ.ox.ac.uk
Low-Frequency Phase Rotation • The UKNF phase rotator evolved from the CERN design • DE reduction occurs in a single RF bucket: • Rees design uses 31.4MHz RF to achieve 180±23MeV intended for a cooling ring Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006
Problem with Two Signs • Negative muons are rotated backwards Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006
Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006
Solution (idea) for Two Signs I. Mixed-sign drifted bunch from decay channel II. Separate signs with on-peak RF III. Drift further to get separation in time IV. Put bunches on opposite sides of two adjacent wave troughs, to get the reverse sign separation and remaining phase rotation simultaneously Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006
Does Dual-Sign Idea Work? • Initial concept worked moderately well • Some optimisation gave a solution for 31.4MHz Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006
Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006
Multi-Harmonic System • Idea: allowing variation of RF frequencies in the optimisation could produce higher yields by better shaped rotation • Allowed harmonics h=n/6 from 1/6 to 4 times the 31.4MHz fundamental • Re-synchronisation every 6 periods (191ns) • My optimisation produced one solution • Summer student produced several others! Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006
Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006
Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006
(27.9,58.7)% Arithmetic mean = 43.3% Comparison of Yields Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006
Other Parameters Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006
Conclusion • The dual-sign problem with lower frequency (few-bucket) phase rotation schemes has been addressed • Bunch train is 50-100ns instead of ~300ns as with 200MHz/Neuffer rotation • Yields compare favourably • 43.3% into ±23MeV hard limit (48% into 28) • c.f. 57% into 28MeV 1-sigma ( 39% into 28) Stephen Brooks, Matthew McCullough BENE meeting, Frascati, November 2006