Sampling Fractions and Electron Shower Shapes.

Peryshkin, A. ; Raja, R.

Technical Information Center Oak Ridge Tennessee

关键词: Electrons;    Accelerators;    Algorithms;    Calorimeters;    Correlations;   

RP-ID  :  DE20121038160

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

We study the usage of various definitions of sampling fractions in understanding electron shower shapes in a sampling multilayer electromagnetic calorimeter. We show that the sampling fractions obtained by the conventional definition (I) of (average observed energy in layer)/(average deposited energy in layer) will not give the best energy resolution for the calorimeter. The reason for this is shown to be the presence of layer by layer correlations in an electromagnetic shower. The best resolution is obtained by minimizing the deviation from the total input energy using a least squares algorithm. The sampling fractions obtained by this method (II) are shown to give the best resolution for overall energy. We further show that the method (II) sampling fractions are obtained by summing the columns of a non-local e tensor that incorporates the correlations. We establish that the sampling fractions (II) cannot be used to predict the layer by layer energies and that one needs to employ the full e tensor for this purpose. This effect is again a result of the correlations.