A Layer Correlation technique for pion energy calibration at the 2004 ATLAS Combined Beam Test

TL;DR

This paper introduces a principal component analysis-based method for calibrating the hadronic energy response of a segmented calorimeter, significantly improving energy resolution for pion beams in the ATLAS experiment.

Contribution

It presents a novel layer correlation technique utilizing longitudinal shower development to enhance pion energy calibration in a segmented calorimeter.

Findings

Energy reconstruction within 3% accuracy for 20-180 GeV pions

Energy resolution improved by 11-25% over electromagnetic scale

Method successfully applied to beam test data from CERN H8

Abstract

A new method for calibrating the hadron response of a segmented calorimeter is developed and successfully applied to beam test data. It is based on a principal component analysis of energy deposits in the calorimeter layers, exploiting longitudinal shower development information to improve the measured energy resolution. Corrections for invisible hadronic energy and energy lost in dead material in front of and between the calorimeters of the ATLAS experiment were calculated with simulated Geant4 Monte Carlo events and used to reconstruct the energy of pions impinging on the calorimeters during the 2004 Barrel Combined Beam Test at the CERN H8 area. For pion beams with energies between 20 GeV and 180 GeV, the particle energy is reconstructed within 3% and the energy resolution is improved by between 11% and 25% compared to the resolution at the electromagnetic scale.