Emilio A. Nanni, Martin Breidenbach, Caterina Vernieri, Sergey Belomestnykh, Pushpalatha Bhat, Sergei Nagaitsev, Mei Bai, Tim Barklow, Ankur Dhar, Ram C. Dhuley, Chris Doss, Joseph Duris, Auralee Edelen, Claudio Emma, Josef Frisch, Annika Gabriel, Spencer Gessner, Carsten Hast, Arkadiy Klebaner, Anatoly K. Krasnykh, John Lewellen, Matthias Liepe, Michael Litos, Jared Maxson, David Montanari, Pietro Musumeci, Cho-Kuen Ng, Mohamed A. K. Othman, Marco Oriunno, Dennis Palmer, J. Ritchie Patterson, Michael E. Peskin, Thomas J. Peterson, Ji Qiang, James Rosenzweig, Vladimir Shiltsev, Evgenya Simakov, Bruno Spataro, Emma Snively, Sami Tantawi, Glen White
C is an opportunity to realize an ee collider for the study of the Higgs boson at GeV, with a well defined upgrade path to 550 GeV while staying on the same short facility footprint. C is based on a fundamentally new approach to normal conducting linear accelerators that achieves both high gradient and high efficiency at relatively low cost. Given the advanced state of linear collider designs, the key system that requires technical maturation for C is the main linac. This white paper presents the staged approach towards a facility to demonstrate C technology with both Direct (source and main linac) and Parallel (beam delivery, damping ring, ancillary component) R&D. The white paper also includes discussion on the approach for technology industrialization, related HEP R&D activities that are enabled by C R&D, infrastructure requirements and siting options.