Differentiable Simulation of a Liquid Argon Time Projection Chamber

TL;DR

This paper presents a differentiable simulator for liquid argon time projection chambers, enabling simultaneous calibration of all detector parameters through gradient-based optimization, improving the realism of particle detection simulations.

Contribution

The paper introduces the first differentiable simulator for LArTPC detectors, allowing for comprehensive, simultaneous calibration of detector parameters using gradient-based methods.

Findings

Enables simultaneous calibration of all detector parameters

Maintains physics fidelity while providing meaningful gradients

Facilitates integration into physics analysis pipelines

Abstract

Liquid argon time projection chambers (LArTPCs) are widely used in particle detection for their tracking and calorimetric capabilities. The particle physics community actively builds and improves high-quality simulators for such detectors in order to develop physics analyses in a realistic setting. The fidelity of these simulators relative to real, measured data is limited by the modeling of the physical detectors used for data collection. This modeling can be improved by performing dedicated calibration measurements. Conventional approaches calibrate individual detector parameters or processes one at a time. However, the impact of detector processes is entangled, making this a poor description of the underlying physics. We introduce a differentiable simulator that enables a gradient-based optimization, allowing for the first time a simultaneous calibration of all detector parameters. We describe the procedure of making a differentiable simulator, highlighting the challenges of retaining the physics quality of the standard, non-differentiable version while providing meaningful gradient information. We further discuss the advantages and drawbacks of using our differentiable simulator for calibration. Finally, we provide a starting point for extensions to our approach, including applications of the differentiable simulator to physics analysis pipelines.