Physics design of beamline for single proton generation at the CSNS accelerator complex

The CSNS-II upgrade project aims to increase the proton beam power from 100 kW to 500 kW and expand experimental capabilities with two new application terminals: a low-flux (single) proton irradiation testing facility(HPES) and a dedicated muon production station. As part of this initiative, we present here a novel beamline design capable of delivering on-demand single proton at the terminal. The beamline design incorporates multiple critical subsystems: (1) proton extraction from the RCS ring via a rotated scattering target (2) beam bifurcation at the RTBT (Ring-to-Target Beam Transport) line utilizing fast kicker and lambertson system (3) segregation of the low-flux proton branch for HPES experiments and the high-flux branch dedicated to muon production, (4) a tunable energy degrader, (5) a two-stage collimator in horizontal and vertical plane, respectively, and (6) integrated beam diagnostics including plastic scintillating detector. A start-to-end simulation shows that this realistic beamline design can successfully achieves all critical requirements of the proton experiment platform.