EJC Physics H220 Nuclear Physics - 1. Notes (2024) - Full

Page 1 of 34 9749(2024) H2 Physics H220 Nuclear Physics – Notes H2 Topic 20 – Nuclear Physics The Sun is powered by nuclear fusion in its core. The core converts approximately 10 38 protons/second into helium at a temperature of 14 million K. This process releases energy in the form of photons, neutrinos, and other particles. (EIT - Extreme ultraviolet Imaging Telescope Consortium, The Solar and Heliospheric Observatory, NASA) Content • The nucleus • Isotopes • Nuclear processes • Mass defect and nuclear binding energy • Radioactive decay • Biological effects of radiation Learning Outcomes Candidates should be able to: (a) infer from the results of the Rutherford α -particle scattering experiment the existence and small size of the atomic nucleus (b) distinguish between nucleon number (mass number) and proton number (atomic number) (c) show an understanding that an element can exist in various isotopic forms each with a different number of neutrons in the nucleus (d) use the usual notation for the representation of nuclides and represent simple nuclear reactions by nuclear equations of the form 14 4 17 1 7 2 8 1N He O H+ → + (e) state and apply to problem solving the concept that nucleon number, charge and mass -energy are all conserved in nuclear processes (f) show an understanding of the concept of mass defect (g) recall and apply the equivalence relationship between energy and mass as represented by E = mc2 to solve problems (h) show an understanding of the concept of nuclear binding energy and its relation to mass defect (i) sketch the variation of binding energy per nucleon with nucleon number (j) explain the relevance of binding energy per nucleon to nuclear fusion and to nuclear fission (k) show an understanding of the spontaneous and random nature of nuclear decay (l) infer the random nature of radioactive decay from the fluctuations in count rate (m) show an understanding of the origin and significance of background radiation (n) show an understanding of the nature of α, β and γ radiations (knowledge of positron emission is not required) (o) show an understanding of how the conservation laws for energy and momentum in β decay were used to predict the existence of the neutrino (knowledge of antineutrino and antiparticles is not required) (p) define the terms activity and decay constant and recall and solve problems using the equation A = λN (q) infer and sketch the exponential nature of radioactive decay and solve problems using the relationship x = x0 exp(–λt) where x could represent activity, number of undecayed particles or received count rate (r) define and use half-life as the time taken for quantity x to reduce to half its initial value (s) solve problems using the relation 1/2 ln 2 t = (t) discuss qualitatively the effects, both direct and indirect, of ionising radiation on living tissues and cells.

Page 2 of 34 9749(2024) H2 Physics H220 Nuclear Physics – Notes 20.