CsI(Tl) Pulse Shape Discrimination with the Belle II Electromagnetic Calorimeter as a Novel Method to Improve Particle Identification at Electron-Positron Colliders

Abstract

This paper describes the implementation and performance of CsI(Tl) pulse shape discrimination for the Belle II electromagnetic calorimeter, representing the first application of CsI(Tl) pulse shape discrimination for particle identification at an electron-positron collider. The pulse shape characterization algorithms applied by the Belle II calorimeter are described. Control samples of $\gamma$, ${\mu }^{+}$, ${\pi }^{\pm }$, $K^{\pm }$ and $p/\bar{p}$ are used to demonstrate the significant insight into the secondary particle composition of calorimeter clusters that is provided by CsI(Tl) pulse shape discrimination. Comparisons with simulation are presented and provide further validation for newly developed CsI(Tl) scintillation response simulation techniques, which when incorporated with GEANT4 simulations allow the particle dependent scintillation response of CsI(Tl) to be modelled. Comparisons between data and simulation also demonstrate that pulse shape discrimination can be a new tool to identify sources of improvement in the simulation of hadronic interactions in materials. The $K_L^0$ efficiency and photon-as-hadron fake-rate of a multivariate classifier that is trained to use pulse shape discrimination is presented and comparisons are made to a shower-shape based approach. CsI(Tl) pulse shape discrimination is shown to reduce the photon-as-hadron fake-rate by over a factor of 3 at photon energies of 0.2 GeV and over a factor 10 at photon energies of 1 GeV.

References in corpus (8)

• The BABAR Detector
• Design and Construction of the BESIII Detector
• The antinucleon-nucleon interaction at low energy : annihilation dynamics
• Search for an invisibly decaying $Z^{\prime }$ boson at Belle II in $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}(e^{\pm }{\mu }^{\mp })$ plus missing energy final states
• Measurement of the integrated luminosity of the Phase 2 data of the Belle II experiment
• Pulse-shape discrimination with PbWO${}_4$ crystal scintillators
• Hadronic vs Electromagnetic Pulse Shape Discrimination in CsI(Tl) for High Energy Physics Experiments
• Separation of gamma-ray and neutron events with CsI(Tl) pulse shape analysis

Cited by in corpus (9)

• New perspectives on segmented crystal calorimeters for future colliders
• Measurement of the integrated luminosity of data samples collected during 2019-2022 by the Belle II experiment
• Photon Reconstruction in the Belle II Calorimeter Using Graph Neural Networks
• Novel method for the identification of the production flavor of neutral charmed mesons
• Pulse Shape Simulation and Discrimination using Machine-Learning Techniques
• Particle identification with the Belle II calorimeter using machine learning
• Energetic neutron identification with pulse shape discrimination in pure CsI crystals
• Measurement of the CP asymmetry in $D^{+}\to {\pi }^{+}{\pi }^0$ decays at Belle II
• Measurement of the time-integrated $CP$ asymmetry in $D^0\to {\pi }^0{\pi }^0$ decays at Belle II