
 --- DETECTOR : a kind of (sampling) calorimeter tower 
     with a single layer of absorber followed by a single 
     layer of active material, with the following 
     characteristics:

      *  Box of Iron of dimensions 100cm x 50cm x 50cm 
         (the x-axis is the beam direction).

            Iron:        Z = 26
                         A = 55.85 g/mole
                   density = 7.87 g/cm3
            
      *  followed by another Box of 10cm x 50cm x 50 cm
         filled with carbonic gas CO2 with:

            density = 27 mg / cm3
            pressure = 50 atmosphere   
            temperature = 300 kelvin.
              
            Carbon:        Z = 6
                         A = 12.01 g/mole
            Oxygen:        Z = 8
                         A = 16.00 g/mole

