Hadron energy reconstruction for ATLAS barrel combined calorimeter using non-parametric method

Hadron energy reconstruction for the ATLAS barrel prototype combined calorimeter in the framework of the non-parametrical method is discussed. The non-parametrical method utilizes only the known e/h ratios and the electron calibration constants and does not require the determination of any parameters by a minimization technique. Thus, this technique lends itself to fast energy reconstruction in a first level trigger. The reconstructed mean values of the hadron energies are within \pm1% of the true values and the fractional energy resolution is [(58\pm 3)%{\sqrt{GeV}}/\sqrt{E}+(2.5\pm0.3)%]\bigoplus(1.7\pm0.2) GeV/E. The value of the e/h ratio obtained for the electromagnetic compartment of the combined calorimeter is 1.74\pm0.04. Results of a study of the longitudinal hadronic shower development are also presented.