Positron beams, both polarized and unpolarized, are identified as important ingredients for the experimental programs at the next generation of lepton accelerators. In the context of the hadronic ...physics program at Jefferson Lab (JLab), positron beams are complementary, even essential, tools for a precise understanding of the electromagnetic structure of nucleons and nuclei, in both the elastic and deep-inelastic regimes. For instance, elastic scattering of polarized and unpolarized electrons and positrons from the nucleon enables a model independent determination of its electromagnetic form factors. Also, the deeply-virtual scattering of polarized and unpolarized electrons and positrons allows unambiguous separation of the different contributions to the cross section of the lepto-production of photons and of lepton-pairs, enabling an accurate determination of the nucleons and nuclei generalized parton distributions, and providing an access to the gravitational form factors of the energy-momentum tensor. Furthermore, positron beams offer the possibility of alternative tests of the Standard Model of particle physics through the search of a dark photon, the precise measurement of electroweak couplings, and the investigation of charged lepton flavor violation. This document discusses the perspectives of an experimental program with high duty-cycle positron beams at JLab.
The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of ...polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-\(Z\) target. Positron polarization up to 82\% have been measured for an initial electron beam momentum of 8.19~MeV/\(c\), limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.
Design of an 830 MeV/c out-of-plane spectrometer
Nuclear instruments and methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment/Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/1994
Journal Article
Positron Beams At Ce\(^+\)BAF Grames, J; Benesch, J; Bruker, M ...
arXiv (Cornell University),
09/2023
Paper, Journal Article
Odprti dostop
We present a scheme for the generation of a high polarization positron beam with continous wave (CW) bunch structure for the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson ...Laboratory (JLab). The positrons are created in a high average power conversion target and collected by a CW capture linac and DC solenoid.
Previously we presented a design for a kiloWatt demonstration industrial UV FEL 1. Progress has been made in resolving several design issues identified in that work. More exact simulations of the ...injector have resulted in a better estimate of the injector performance. A more compact lattice has been designed meeting the design requirements for the UV FEL, and a new design point has been studied which greatly increases the threshold for longitudinal instabilities. A stability analysis of the RF control system has found that only minor modifications from existing CEBAF controls will be necessary to allow them to be used with a high-current, energy-recovery accelerator. Designs for the optical cavity length and figure systems have been conceptualized and a model of the corner-cube resonator is being built and tested. Finally, three-dimensional simulations of the FEL have been carried out which show that the laser should exceed its minimum design goals for average power.
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