Orateur
Description
Precision measurements in Liquid Argon Time Projection Chambers (LArTPCs) rely on accurate modeling of detector response. In standard calibration workflows, effects such as space charge, recombination, electron lifetime, and electronics response are usually measured independently. This segmented approach ignores correlations among parameters and can introduce systematic biases into the simulation.
Differentiable simulation offers a direct way to address this limitation by providing gradients through the full detector model, enabling all parameters to be optimized at once. Using a LArTPC simulator implemented in JAX, we demonstrate simultaneous multi-parameter calibration on realistic, data-like samples. We discuss practical challenges encountered when moving beyond toy setups, including parameter degeneracies, sample statistics, and detector noise.
In addition, we show how automatic differentiation simplifies systematic uncertainty propagation. Because the simulator provides exact Jacobians and Hessians, the full parameter covariance matrix can be mapped directly to reconstructed physics quantities without relying on computationally expensive re-simulations.