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 hadron response of a segmented calorimeter, significantly improving energy resolution in pion beam tests at CERN.

Contribution

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

Findings

Achieved pion energy reconstruction within 3% accuracy for 20-180 GeV beams.

Improved energy resolution by approximately 20% over the electromagnetic scale.

Validated the method with simulated and real beam test data.

Abstract

A new method for calibrating the hadron response of a segmented calorimeter is developed. It is based on a principal component analysis of the calorimeter layer energy deposits, 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 ATLAS calorimeters 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 and 180 GeV, the particle energy is reconstructed within 3% and the energy resolution is improved by about 20% compared to the electromagnetic scale.