At what energies will the photoelectric effect, compton scattering, and pair production be the most important process for energy loss of photons in tissi 3. why is there a threshold for pair production?

Explained

Explanation:

The minimum energy required by a photon to create a electron-positron pair must be equal to the sum of rest mass energies of both electron and positron.

therefore E= 2m_ec^2

=2×0.511 MeV

=1.02 MeV

Below this , the process would not occur. So, in the energy range of > 1.02 MeV

The most dominant process will be in pair production.

At the range of 200 KeV to 3 MeV, The most dominant Process is compton Scattering.

below 200 KeV , Photo electric effect is more dominant.

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg