In general, the total stopping power for a given charged particle is the sum of collision (electronic) stopping power and radiation stopping power. However, as we saw in class, for heavy charged particles the total stopping power is equal to the collision stopping power, since the radiation stopping power for heavy charged particles is negligible in comparison with the collision stopping power. (i) Using Bethe-Bloch's expression for the stopping power, calculate the mass stopping power of water for a proton of kinetic energy Ep = 100 MeV. The mean excitation energy of water / is 75 eV. (ii) Repeat the calculation for 1 MeV and 10 MeV protons in water. (iii) Calculate the kinetic energy of the deuteron (moc² = 1875.6 MeV) for which the stopping power of water is the same as that for the proton in (i). (iv) Calculate the stopping power of water for an a particle (mac² = 3727.3.6 MeV) having the same velocity as the proton in (i). (v) Compare the results obtained in (i) and (ii) for protons and in (v) for a particles with data available from NIST for stopping power for protons and a particles (https://physics.nist.gov/PhysRefData/Star/Text/PSTAR.html).

In general, the total stopping power for a given charged particle is the sum of collision (electronic) stopping power and radiation stopping power. However, as we saw in class, for heavy charged particles the total stopping power is equal to the collision stopping power, since the radiation stopping power for heavy charged particles is negligible in comparison with the collision stopping power. (i) Using Bethe-Bloch's expression for the stopping power, calculate the mass stopping power of water for a proton of kinetic energy Ep = 100 MeV. The mean excitation energy of water / is 75 eV. (ii) Repeat the calculation for 1 MeV and 10 MeV protons in water. (iii) Calculate the kinetic energy of the deuteron (moc² = 1875.6 MeV) for which the stopping power of water is the same as that for the proton in (i). (iv) Calculate the stopping power of water for an a particle (mac² = 3727.3.6 MeV) having the same velocity as the proton in (i). (v) Compare the results obtained in (i) and (ii) for protons and in (v) for a particles with data available from NIST for stopping power for protons and a particles (https://physics.nist.gov/PhysRefData/Star/Text/PSTAR.html).