On planar (110) channeling of 500 MeV positrons and electrons in silicon semiconductor detectors

The investigation of the channeling phenomenon of positrons in single crystals relies on the availability of high quality positron beams. At the Mainz Microtron MAMI a facility is under construction which will supply a 500 MeV positron beam (Backe et al., 2022) with an emittance of ϵv = 0.055 πmm mrad (1 σ) in vertical direction. The beam line allows focusing of the positron beam in the target chamber with an angular spread of 64 μrad (FWHM) at a beam width of 5 mm (FWHM). Employing a silicon detector oriented in (110) channeling conditions, it is intended to measure in a triple coincidence the energy loss of the positrons in the silicon detector, as proposed in a recent paper by A.V. Shchagin (Shchagin et al., 2022), the scattering angle and the energy of the emitted photons. In this paper a case study is presented with the aid of simulation calculations for such an experiment with special emphasis on the role of the plasmon resonances in silicon at 17 and 3.9 eV. Simulation results are presented for an electron beam of 500 MeV from MAMI as well.