Wednesday 20 June 2012 

Speaker: John Marshall (University of Cambridge)


Title: "Particle Flow Calorimetry and the Pandora Algorithm"

Abstract: "A next generation lepton collider, such as the ILC or CLIC, 
has the potential to precisely measure the properties of the Higgs boson 
and/or other particles expected to be discovered at the LHC. However, 
physics analyses at such a collider will place unprecedented demands 
on calorimetry, with a required jet energy resolution of $\sigma(E)/E<3.5\%$, 
a factor of 2-3 times better than achieved at LEP. To meet these requirements
will need a new approach to calorimetry.

The particle flow approach to calorimetry requires both fine granularity 
detectors and sophisticated software algorithms. It promises to deliver 
unparalleled jet energy resolution by fully reconstructing the paths of 
individual particles through the detector. The energies of charged particles 
can then be extracted from precise inner detector tracker measurements, 
whilst photon energies will be measured in the ECAL, and only neutral 
hadron energies (10\% of jet energy) will be measured in the HCAL, 
largely avoiding the intrinsically poor HCAL resolution.

This talk will introduce the Pandora particle flow algorithms, which offer 
the current state of the art in particle flow calorimetry for the ILC and 
CLIC. The talk will discuss the performance of Pandora for fully simulated 
and reconstructed events and it will describe how Pandora has been used to 
optimise detector design. Finally, findings from the recent CLIC Conceptual 
Design Report will be discussed. These findings indicate that the combination 
of Pandora and currently available detector technologies will enable precision 
physics measurements, even in the challenging 3TeV CLIC environment".