float active_thickness = 1.2
float active_aeff = 6.509
float active_zeff = 3.5
float active_rho = 1.032
string active_name = "Polystyrene"
string active_symbol = "C6H5CH--CH2"

float lead_thickness = 1.1199
float lead_aeff = 207.19
float lead_zeff = 82
float lead_rho = 11.35
string lead_name = "Lead"
string lead_symbol = "Pb"