Performance analysis of the CMS Zero Degree Calorimeters (ZDC)

We published a paper on the subject [1]. In this paper we present our studies of the CMS ZDC using proton-lead collisions measured in 2016. First, we developed a template fitting method, which can be used to extract accurate values of the ZDC signals in the presence of collisions preceding our main signal. We also improved the Monte Carlo simulation of the ZDC, including the modeling of Cherenkov photons. We have shown that the properties of the measured ZDC signals can be reproduced by this simulation and can be used to match the gains of the ZDC channels. As a result, we measured the energy distribution of neutrons emitted from the collisions at shallow angles; we have found peaks corresponding to single, double and triple neutron events (Fig. 1). Finally, we studied the effect of multiple simultaneous collisions and derived a Fourier deconvolution formula to correct the measured energy distribution in the ZDC. The corrected spectrum can be used to determine the centrality of p-Pb collisions.