2:11 Nuclear Done Queen Mary University of London, 2020 2 of 8 Page 2 SPA5302 (2020) SECTION A Answer ALL questions in Section A Question A1 Cobalt-59 may be written as Co. State the mass number, and the number of neutrons and the number of protons of Cobalt-59. Iron lies immediately to the left of Cobalt on the periodic table. How many neutrons does Fe have? [5 marks] Question A2 Explain, with the aid of suitable graphs, how scattering experiments can probe the density profile of a nucleus. [5 marks] Question A3 Sketch a graph of the table of nuclides with N, the number of neutrons, along the horizontal axis and Z, the number of protons, along the vertical axis. On this diagram sketch the line N = Z. With reference to this line, sketch the area of known nuclides, indicating the area where stable nuclei are found. Indicate the regions in which 8, 3+ and a decay occur. [5 marks] Question A4 Give 5 features of the nuclear force, together with an appropriate sketch of the nucleon-nucleon potential. Question A5 [5 marks] Sketch an energy level diagram using the shell model for the nuclei Ar clearly labelling each energy level. Explain how to find the ground state spin and parity. [5 marks] SPA5302 (2020) Question A6 Page 3 A nuclide Ac decays to 2Th which then decays to 22 Ra. State the decay mechanism for each decay. Write down the reactions involved. Question A7 C [5 marks] 2:11 3 of 8 Nuclear Done SPA5302 (2020) Question A6 Page 3 A nuclide Ac decays to 25Th which then decays to 22 Ra. State the decay mechanism for each decay. Write down the reactions involved. [5 marks] Question A7 da. In an a-decay XY+a give the Q-factor in terms of the binding energies of X, Y, and a. State the necessary condition in terms of Q for the decay to occur. [5 marks] Question A8 A 235U nucleus absorbs a neutron. Calculate the excitation energy of the combined system. Compare this to the activation energy 6.2 MeV. By considering the activation and the excitation energies, state the likely outcome for the nucleus. [5 marks] Question A9 The Coulomb barrier for a deuteron-deuteron collision is 0.475 MeV. Calculate the temperature a gas of deuterium would have to have for sufficient thermal energy to overcome this. Explain, with the aid of a suitable graph, why this barrier is overcome even in much cooler gases. Question A10 Give an account of the main nuclear reactions taking place in the Sun. Page 4 Question B1 C [5 marks] [5 marks] Turn over SPA5302 (2020) SECTION B Answer TWO questions from Section B