Wednesday 7 February 2018 

Speaker: Alan Watson (University of Leeds)


Title: "Insights into hadronic physics beyond LHC energies from studies of cosmic rays with the Pierre Auger Observatory”

Abstract: The Pierre Auger Observatory was designed to study the properties of cosmic rays with energies above 1018 eV to 
beyond 1020 eV and with it results of importance for astrophysics and particle physics have been obtained.  The astrophysical 
interest lies in discovering the sources of these particles and for this one needs to measure the energy spectrum and the 
mass composition: the measurements rely, to a lesser and greater extent respectively, on knowledge of hadronic physics, 
such as cross-section, multiplicity and inelasticity, at centre-of-mass energies up to ~30 times above what is accessible 
at the LHC.  After describing the Auger Observatory, I will discuss our calorimetric measurement of the primary energy 
which can be made with an accuracy of ~ 10%, independent of the unknown hadronic physics, and the astrophysical implications 
of the result which also require knowledge of the primary mass.  I will mention – very briefly – two new results on the 
anisotropy of the highest-energy particles.