  Simulating high-resolution detector responses is a computationally intensive
process that has long been challenging in Particle Physics. Despite the ability
of generative models to streamline it, full ultra-high-granularity detector
simulation still proves to be difficult as it contains correlated and
fine-grained information. To overcome these limitations, we propose Intra-Event
Aware Generative Adversarial Network (IEA-GAN). IEA-GAN presents a Relational
Reasoning Module that approximates an event in detector simulation, generating
contextualized high-resolution full detector responses with a proper relational
inductive bias. IEA-GAN also introduces a Self-Supervised intra-event aware
loss and Uniformity loss, significantly enhancing sample fidelity and
diversity. We demonstrate IEA-GAN's application in generating sensor-dependent
images for the ultra-high-granularity Pixel Vertex Detector (PXD), with more
than 7.5 M information channels at the Belle II Experiment. Applications of
this work span from Foundation Models for high-granularity detector simulation,
such as at the HL-LHC (High Luminosity LHC), to simulation-based inference and
fine-grained density estimation. To our knowledge, IEA-GAN is the first
algorithm for faithful ultra-high-granularity full detector simulation with
event-based reasoning.
