  The Monte Carlo Computational Summit was held on the campus of the University
of Notre Dame in South Bend, Indiana, USA on 25--26 October 2023. The goals of
the summit were to discuss algorithmic and software alterations required for
successfully porting respective code bases to exascale-class computing
hardware, compare software engineering techniques used by various code teams,
and consider the adoption of industry-standard benchmark problems to better
facilitate code-to-code performance comparisons. A large portion of the meeting
included candid discussions of direct experiences with approaches that have and
have not worked. Participants reported that identifying and implementing
suitable Monte Carlo algorithms for GPUs continues to be a sticking point. They
also report significant difficulty porting existing algorithms between GPU APIs
(specifically Nvidia CUDA to AMD ROCm). To better compare code-to-code
performance, participants decided to design a C5G7-like benchmark problem with
a defined figure of merit, with the expectation of adding more benchmarks in
the future. Problem specifications and results will eventually be hosted in a
public repository and will be open to submissions by all Monte Carlo transport
codes capable of running the benchmark problem. The participants also
identified the need to explore the intermediate and long-term future of the
Monte Carlo neutron transport community and how best to modernize and
contextualize Monte Carlo as a useful tool in modern industry. Overall the
summit was considered to be a success by the organizers and participants, and
the group shared a strong desire for future, potentially larger, Monte Carlo
summits.
