Radiofrequency Accelerator R$\&$D Strategy Report: DOE HEP General Accelerator R$\&$D RF Research Roadmap Workshop, March 8-9, 2017

Over a two-day period, March 8-9, 2017 the Office of High Energy Physics convened a workshop in Gaithersburg, MD to seek community input on development of a radiofrequency (RF) research ten-year roadmap to guide the General Accelerator Research and Development Program (GARD). As described in the charge, the roadmap should reflect the Particle Physics Project Prioritization Panel strategy and the subsequent HEPAP Accelerator Subpanel recommendations. The charge for the workshop can be found in Appendix A. At the workshop, proponents of superconducting radiofrequency technology (SRF) and normal conducting radiofrequency technology (NCRF), along with invited university and laboratory experts, critically discussed opportunities, gaps, and requirements relevant to the development of a roadmap. The roadmap workshop was preceded by preparatory workshops at SLAC on NCRF and Fermilab on SRF.