The lateral and longitudinal profiles of hadronic showers detected by a pro
totype of the ATLAS Iron-Scintillator Tile Hadron Calorimeter have been inv
estigated. This calorimeter presents a unique longitudinal configuration of
scintillator tiles. Using a fine-grained pion beam scan at 100 GeV. a deta
iled picture of transverse shower behaviour is obtained. The underlying rad
ial energy densities for the four depth segments and for the entire calorim
eter have been reconstructed. A three-dimensional hadronic shower parametri
sation has been developed. The results presented here are useful for unders
tanding the performance of iron-scintillator calorimeters, for developing f
ast simulations of hadronic showers, for many calorimetry problems requirin
g the integration of a shower energy deposition in a volume and for future
calorimeters design. (C) 2000 Elsevier Science B.V. All rights reserved.