Holographic Synchrotron Radiation Emission Spectroscopy for Muon-to-Electron Conversion Experiments

The detection of charged-lepton-flavor-violating (CLFV) processes would be a major development, indicating the presence of beyond Standard Model physics. Multiple experiments are working to measure muonic branching factors to constrain new physics models. Mu2e will improve current limits on the direct muon to electron conversion (µ^- N → e^- N) rate by four orders of magnitude. Mu2e will use an array of straw tubes to track decay electrons’ momentum-dependent trajectory within a constant magnetic field. The experimental sensitivity depends crucially on the straw tracker’s momentum resolution, but straws induce multiple-scatterings which cause energy broadening, so we explore spectroscopic methods utilizing the energy-dependence of an electron’s emitted radiation for energy determination. In particular, a 105 MeV relativistic electron traverses a constant magnetic field region in a helical path, emitting beamed synchrotron radiation. This radiation lies within the visible band, permitting the use of optical photodetectors to track its projected motion. In this talk, I will discuss background considerations for the holographic synchrotron radiation emission spectroscopy (HSRES) method. In particular, I will discuss the physics processes affecting experimental sensitivity and preliminary pattern recognition algorithms used to cluster track candidates.