Prospects for an experiment to measure $BR(K_L\to {\pi }^0\nu \bar{\nu })$ at the CERN SpS

We are investigating the feasibility of performing a measurement of $BR(K_L\to {\pi }^0\nu \bar{\nu })$ using a high-energy secondary neutral beam at the CERN SPS in a successor experiment to NA62. The timescale would require many years; we assume that the experiment would be ready at the start of LHC Run 4. Some preliminary conclusions from our feasibility studies, design challenges faced and sensitivity obtainable for the measurement are here presented.