Explain the consistent ~20% underestimation of leakage current in simulation

Investigate and determine the cause of the approximately 20% underestimation of silicon sensor leakage current by the CMS silicon strip tracker radiation-damage simulation compared to measurements across tracker layers, and ascertain whether the discrepancy originates from imperfect FLUKA radiation-field modelling, uncertainties in cooling contact and self-heating estimation, or other effects.

Background

Within the Radiation effects section, the authors compare measured silicon sensor leakage currents (scaled to a common temperature and normalized per unit volume) with simulation predictions as a function of integrated luminosity and fluence across tracker layers. While the simulation reproduces overall trends, it consistently underestimates the leakage current by about 20% across all layers.

The paper notes potential contributing factors such as imperfect modelling of the radiation environment in FLUKA and uncertainties in the thermal coupling (cooling contact), which could bias self-heating estimates. However, the specific origin of the discrepancy remains unresolved, motivating a focused investigation to reconcile measurements and simulation.