A surprising method for polarising antiprotons

Abstract

We propose a method for polarising antiprotons in a storage ring by means of a polarised positron beam moving parallel to the antiprotons. If the relative velocity is adjusted to $v/c\approx 0.002$ the cross section for spin-flip is as large as about $2\cdot 10^{13}$ barn as shown by new QED-calculations of the triple spin-cross sections. Two possibilities for providing a positron source with sufficient flux density are presented. A polarised positron beam with a polarisation of 0.70 and a flux density of approximately $1.5\cdot 10^{10}$/(mm${}^2$ s) appears to be feasible by means of a radioactive ${}^{11}$C dc-source. A more involved proposal is the production of polarised positrons by pair production with circularly polarised photons. It yields a polarisation of 0.76 and requires the injection into a small storage ring. Such polariser sources can be used at low (100 MeV) as well as at high (1 GeV) energy storage rings providing a time of about one hour for polarisation build-up of about $10^{10}$ antiprotons to a polarisation of about 0.18. A comparison with other proposals show a gain in the figure-of-merit by a factor of about ten.

13 pages, 8 figures; v2: minor language and signification corrections v3: (14 pages, 12 figures) major error, nonapplicable polarisation transfer cross sections replaced by the mandatory spin-flip cross sections

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Cited by in corpus (10)

• Polarizing a stored proton beam by spin flip?
• Polarization effects in non-relativistic $ep$ scattering
• Forward antiproton-deuteron elastic scattering and total spin-dependent antiproton-deuteron cross sections at intermediate energies
• Model independent analysis of polarization effects in elastic proton-electron scattering
• A method to polarise antiprotons in storage rings and create polarised antineutrons
• Dynamics of polarization buildup by spin filtering
• Coulomb effects in polarization transfer in elastic antiproton and proton electron scattering at low energies
• The Beauty of Spin
• Polarization buildup by spin filtering in storage rings
• Influence of Coulomb distortion on polarization observables in elastic electromagnetic lepton hadron scattering at low energies