The diagram below shows the change in the self-efficiency of the thallium-doped sodium iodine detector (NalTe) as a function of both the eners of the radioactive source and the thickness of the detector crystal (x). (1) Write three scientific observations on changing self-efficacy that can be inferred from Chart above. (2) For a radiant source whose energy is (Me 0.5) and the thickness of the crystal is 1.3cm, calculate the absolute efficiency (p) of the meter if it is conducted so that the angle is (30=0)