Order the following in terms of typical penetration depth in materials, lowest to highest, when the particles initially have an energy in the MeV range. Answer with a string, e.g. ABCD (this is not the correct answer) A. Electrons B. Ions C. Gamma particles D. Neutrons Answer: BADC Whas the atom mass 183.85u and the electron the mass 0.00054858u. The minimum atomic recoil energy needed to create damage in W is 42 eV [F. Maury et al, Radiat. Eff. 38, 53 (1978)]. What is the energy of electrons needed to start creating damage in W in the classical ap- proximation? Answer in units of keV, points are given if answer is within 5% of the correct value. Answer: 7033.1 x W has the atom mass 183.85u and the electron the mass 0.00054858u. Assume that the minimum atomic recoil energy needed to create damage in W is 42 eV. What is the energy of electrons need to start creating damage in W in the relativistic, exact calculation? Answer in units of keV, points are given if answer is within 10% of the correct value. Answer: 83.93 x What are the units of stopping power equivalent to? Select one: a. Power b. Force c. Energy x d. Pressure An energetic carbon ion (mass = 12 amu) with initial energy 30 MeV is penetrating a typical solid, say Si. Which of the following describes best its slowing down before it stops? Select one: 1. It first slows down by collisions with electrons, then speeds up by nuclear collisions. 2. It first slows down mainly by nuclear collisions, then by collisions with electrons which are stronger than those with nuclei 3. It first slows down by collisions with electrons which first strengthen and then weaken, then starts slowing down by nuclear colli- sions which first get stronger and then weaken 4. It first slows down by collisions with electrons which first strengthen and then weaken, then starts slowing down by nuclear x collisions which first weaken and then get stronger. 5. It first slows down by collisions with electrons which continuously weaken, then starts slowing down by nuclear collisions which first get stronger and then weaken 6. It first slows down by collisions with electrons which first weaken and then strengthen, then starts slowing down by nuclear colli- sions which first get stronger and then weaken A gold ion (mass 197 amu) with initial energy of 500 MeV is penetrating a pure elemental metal. Which of the following describes best the mechanism by which it produces damage in the material? Select one or more: 1. It first produces damage by electronic stopping power in an ion track, then starts x producing damage also by nuclear collisions 2. It produces damage only by nuclear collisions 3. It does not produce any damage lon tracks have not been observed in pure elemental metals. It first produces damage by nuclear collisions, then starts producing damage also by electronic stopping power in an ion track. 5. It first produces damage by electronic stopping power in an ion track, then stops down A hydrogen ion (mass 1 amu) with initial energy of 100 eV is penetrating W, which has the threshold displacement energy 40 eV. Which of the following describes best the mechanism by which it produces damage in the material? Select one or more: 1. It produces damage by electronic excitations 2. It kicks a W atom into the vacuum 3. It does not produce any damage 4. It first penetrates the material and then in the end kicks a W atom off its lattice site. *