R.F. Beam Recombination ("Funnelling") at the CERN PSB by Means of an 8 MHz Dipole Magnet

G Nassibian,K Schindl

doi:10.1109/tns.1985.4334172

Abstract

For filling the Antiproton Accumulator ring, the beam in the PS must be concentrated within one quarter of its circumference. A first step is to inject as much beam as possible into two groups of five PS buckets each occupying one quarter of its periphery. For this purpose, beams from the 4-ring injector synchrotron (PSB) are recombined in pairs by means of an RF dipole magnet which permits longitudinal interleaving of successive bunches. Each PSB bunch being slightly under 180° in length, two of them can fit into a (stationary) PS bucket. It is shown that the use of a sinusoidal deflecting field instead of the ideal square wave results in only a modest growth of the transverse emittance of the recombined beams. The increase of longitudinal emittance by a factor of ~ 3, inherent to the scheme is also acceptable for the PS machine. We discuss the beam dynamics aspects, the construction of the 8 MHz, 250 gauss meter deflecting magnet and the experimental results.

Highlights

Introduction and SummaryDeflector desisti’!For filling the Antiproton Accumulator ring, the beam in the PS must be concentrated within one quart.er of its circumference
It is shown that the use of a SlnuSOlddl deflcctlng field instead of the ideal square wave results rn only a modest growth of the transverse emittance of the recombined beams
In the CERN PS complex, antiprotons are produced by an intense proton beam at 26 GeV/c which has to match the circumference r::. the Antiproton Accumulator

Summary

Deflector desisti’!

For filling the Antiproton Accumulator ring, the beam in the PS must be concentrated within one quart.er of its circumference. A first step is to inject as much beam as possible into two groups of flvc PS buckets each occupying one quarter of its perrphery. For this purpose, beams from the 4--rrng rnjector synchrotson (PSB) are recombined in pairs by means of an RF dipole magnet which permits longltudlnal interleaving of successive bunches. It is shown that the use of a SlnuSOlddl deflcctlng field instead of the ideal square wave results rn only a modest growth of the transverse emittance of the recombined beams. We discuss the beam dynamics aspects, the construction of the 8 MHz, 250 gauss meter deflecting magnet and the experimental results

RF Recombination Schemnii

Maanet Construction

The construction is shown rn figures

ExPerImental Results