Sullivan, M.K. JACoW Publishing Geneva, Switzerland 978-3-95450-216-5 10.18429/JACoW-eeFACT2018-WEXBA01 English 194-200 WEXBA01 background photon detector luminosity focusing Contribution to a conference proceedings 2019 2019-04 https://doi.org/10.18429/JACoW-eeFACT2018-WEXBA01 http://jacow.org/eefact2018/papers/wexba01.pdf New e⁺e⁻ accelerator designs aim for factory-like performance with high-current beams and high luminosities. These new machines will push interaction region designs to new levels and require a careful evaluation of all previous background sources as well as introduce possibly new background sources. I present here a summary of standard background sources and also suggest a new possible background source for Synchrotron Radiation (SR) namely, specular reflection. In addition, one will have to pay closer attention to the beam tail particle distribution as this may become a significant source of SR background from the high-current and high-energy beams of these new designs.