Ultra-peripheral heavy ion collisions provide a unique opportunity to study the parton distributions in the colliding nuclei via the measurement of photo-nuclear jet production. An analysis of jet production in ultra-peripheral Pb+Pb collisions at root S-NN = 5.02 TeV performed using data collected with the ATLAS detector in 2015 is described. The data set corresponds to a total Pb+Pb integrated luminosity of 0.38 nb(-1). The ultra-peripheral collisions are selected using a combination of forward neutron and rapidity gap requirements. The cross-sections, not unfolded for detector response, are compared to results from PYTHIA Monte Carlo simulations re-weighted to match a photon spectrum obtained from the STARLIGHT model. Qualitative agreement between data and these simulations is observed over a broad kinematic range suggesting that using these collisions to measure nuclear parton distributions is experimentally realisable.

Angerami, A., Aaboud, M., Aad, G., Abbott, B., Abdallah, J., Abdinov, O., et al. (2017). Measurements of photo-nuclear jet production in Pb plus Pb collisions with ATLAS. ??????? it.cilea.surplus.oa.citation.tipologie.CitationProceedings.prensentedAt ??????? 26th International Conference on Ultrarelativistic Nucleus-Nucleus Collissions (Quark Matter), Chicago, IL [10.1016/j.nuclphysa.2017.06.041].

Measurements of photo-nuclear jet production in Pb plus Pb collisions with ATLAS

Aielli, G.;Camarri, P.;Cerrito, L.;Di Ciaccio, A.;Pinamonti, M.;