  Pulse shape discrimination using CsI(Tl) scintillators to perform neutral
hadron particle identification is explored with emphasis towards application at
high energy electron-positron collider experiments. Through the analysis of the
pulse shape differences between scintillation pulses from photon and hadronic
energy deposits using neutron and proton data collected at TRIUMF, it is shown
that the pulse shape variations observed for hadrons can be modelled using a
third scintillation component for CsI(Tl), in addition to the standard fast and
slow components. Techniques for computing the hadronic pulse amplitudes and
shape variations are developed and it is shown that the intensity of the
additional scintillation component can be computed from the ionization energy
loss of the interacting particles. These pulse modelling and simulation methods
are integrated with GEANT4 simulation libraries and the predicted pulse shape
for CsI(Tl) crystals in a $5 \times 5$ array of $5 \times 5 \times 30 \text{
cm}^3$ crystals is studied for hadronic showers from 0.5 and 1 GeV/c $K_L^0$
and neutron particles. Using a crystal level and cluster level approach for
photon vs hadron cluster separation we demonstrate proof-of-concept for neutral
hadron detection using CsI(Tl) pulse shape discrimination in high energy
electron-positron collider experiments.
