Positron annihilation spectroscopy measurements have been performed to assess the vacancy concentration in single crystal copper (Tm=1083C, face centered cubic crystal structure with ao=0.3615nm,A=63.55g/mol,Do=105m2/s, and with an activation energy for vacancy migration =0.7eV ) as a function of thermal annealing temperature between 675 and 1000C, and the measured vacancy concentrations are provided in the table below. a) What is the vacancy formation energy in copper? b) At 50% of the melting temperature, calculate the thermodynamic equilibrium vacancy concentration and the value of the self-diffusion coefficient