Theoretical Estimation of Energy Resolution in Liquid Argon Sampling Calorimeter

Abstract

A new method for estimating the energy resolution of the multi-lead-plate liquid argon calorimeter (Rm≈tc) and a new formula for the energy resolution of the multi-iron-plate liquid argon calorimeter (Rm≫tc) are presented, where Rm is the average range of secondary electrons or positrons and tc is the thickness of the unit cell. In the former case, the estimation is made by considering that the energy resolution is given by the sampling fluctuation of deposited energy in the liquid argon gap, assuming that the ionization losses in liquid argon gaps due to secondary particles have no correlation with each other. In the latter case, we cannot accept such an assumption, so a new formula for the energy resolution is derived from an analogy with Fano's formalism for the straggling of the total ionization produced by ionizing radiation with a fixed energy. A comparison with the results of Monte Carlo calculation and the experimental data shows that these can be used for estimating the energy resolution of the multi-plate liquid argon calorimeter with a wide liquid argon gap.