1. (20%) You are currently working for a nuclear facility and your manager wants you to calculate the thickness in cm of a tungsten shield needed to reduce the gamma flux of Cs-137 source from 100 to 102 y/cm² s. The tungsten density is 18.82 g/cm³. Cs-137 has a half-life of 30.08 years and emits a 0.662 MeV photon. The last page contains more information for this problem (Hint: Use µ/p). D= E Pen/P Hen/p mass energy-absorption coefficient