Feasibility and conceptual design of a C.W. positron source at CEBAF

Abstract

The efficiency and equivalent current at 10 mA incoming electron beam 93 Lattice description of the Combined Function Magnet configuration . 95 The efficiency and equivalent current at 10 mA incoming electron beam112 Lattice description of the two sector dipole configuration . . . . . . .

High-intensity positron microprobe at the Thomas Jefferson National Accelerator Facility

“…Some of these experiments would benefit from our proposed positron beamline as well since the energy distribution of the produced positrons extends up to 120 MeV with the potential to transport a several µA positron beam current at peak energies. 27…”

An experimental program with high duty-cycle polarized and unpolarized positron beams at Jefferson Lab

“…Even more ambitious alternative concepts may also be sketched, like starting from a positron-dedicated, high-intensity electron accelerator [177], or implementing a PEPPo source with multi-GeV electrons. Beyond these considerations, the propagation of positrons into CEBAF is an additional concern requiring, among others, to change the polarity of arc-recirculating magnets and to upgrade beam diagnostics.…”

Physics perspectives at JLab with a polarized positron beam

“…While each location has specific issues, the common technical and technological challenges comprise: a high intensity polarized positron source capable of a few-mA continuous beam delivery with high polarization degree; a high power (10-100 kW) production target challenging for heat dissipation, radiation management, and accelerator integration; an optimized positron collection system for the delivery of quality beams for physics experiments; a positron beam shaping system to prepare for further acceleration or decelaration. Optimization of each scenario is obviously a multi-parameter problem but conceptual studies are already promising: a full lattice simulation based on a 100 MeV/1 mA electron beam driver showed that positron beam intensities up to 300 nA can be expected with a momentum spread of 10 −2 and a beam emittance (ε x ε y ) = (1.6, 1.7) mm.mrad [19], PEPPo indicating further that polarizations larger than The Journal's name 60% of the initial electron beam polarization can be achieved. Such a beam would definitely fulfills requirements for the study of the nucleon structure, for instance with the CLAS12 detector.…”