Reconstructing the impact parameter of proton-nucleus and nucleus-nucleus collisions

Understand

In proton-nucleus and nucleus-nucleus collision experiments, one determines the centrality of a collision according to the multiplicity or energy deposited in a detector.

• This serves as a proxy for the true collision centrality, as defined by the impact parameter.
• We show that the probability distribution of impact parameter in a given bin of experiment-defined centrality can be reconstructed without assuming any specific model for the collision dynamics, in both proton-nucleus and nucleus-nucleus systems.
• The reconstruction is reliable up to about 10\% centrality, and is more accurate for nucleus-nucleus collisions.