
               *******************
               ***  MANDATORY  ***
               *******************


 --- ANALYSIS : add to the previous exercise (10_analysis/)
     two histograms and two variables to the ntuple relative
     to the following event information about the "tracker" part: 

       *  number of hits in the silicon layer;      

       *  energy deposited in the silicon layer;

     (this is the same information which has been printed out
      in the example 9b/).
