# Backward Monte-Carlo applied to muon transport

## TL;DR

This paper introduces a backward Monte-Carlo method for muon transport, implemented in the PUMAS library, demonstrating high accuracy and potential advantages for muography imaging applications.

## Contribution

It presents a novel backward Monte-Carlo technique for muon transport, offering greater versatility and comparable accuracy to forward schemes in muography.

## Key findings

- Backward Monte-Carlo agrees with forward schemes within 1% accuracy.
- The PUMAS library successfully implements the backward Monte-Carlo method.
- The approach enhances muography imaging capabilities.

## Abstract

We discuss a backward Monte-Carlo technique for muon transport problem, with emphasis on its application in muography. Backward Monte-Carlo allows exclusive sampling of a final state by reversing the simulation flow. In practice it can be made analogous to an adjoint Monte-Carlo, though it is more versatile for muon transport. A backward Monte-Carlo was implemented as a dedicated muon transport library: PUMAS. It is shown for case studies relevant for muography imaging that the implementations of forward and backward Monte-Carlo schemes agree to better than 1%.