Lecture Physics A2: Nuclear physics - PhD. Pham Tan Thi present the content fundamentals of atom and nuclei, nuclides and isotopes, magnetic moments, NMR and magnetic resonance imaging, stable nuclei and unstable nuclei, . | Nuclear Physics Pham Tan Thi . Department of Biomedical Engineering Faculty of Applied Sciences Ho Chi Minh University of Technology Fundamentals of Atom and Nuclei Nuclides and Isotopes Electron and nucleon masses 12C nucleus is defined to have u Proton mp u Neutron mn u Electron me u The atomic number Z is the number of protons in the nucleus. The neutron number N is the number of neutrons in the nucleus. A Z N A nuclide is an atom of a particular structure. Each element has nucleus with a specific number of protons. Nuclide notation A ZX A Number of Nucleons Z Number of Protons Electrons 12 1 0 1 Example Carbon 1C Neutron 0n Electron -1e Proton 1p Fundamentals of Atom and Nuclei The number of nucleons A also called the mass number is the total number of protons and neutrons in the nucleus. The nucleon mass is measured in atomic mass unit u slightly less than the mass of the proton 1 u x 10-27 kg The radius of most nuclei is given by R RoA1 3 where Ro is experimentally determined as Ro x 10-15 m fm All nuclei have approximately the same density. Example Common iron nuclei has mass number 56. Find the radius approximate mass and density of an iron nucleus. R Ro A1 3 10 15 m 56 1 3 fm 27 26 m 56 u 10 kg 10 kg 4 3 4 15 V R 10 m 3 10 43 m3 3 3 m 10 26 kg 17 3 Nucleus is 1013 times 43 10 kg m the density of iron V 10 m3 Magnetic Moments Like electrons nucleons have 1 2-integer spin angular momentum obeying the same relations as electron spin p S s s 1 The z-component is itself a quantum number as electron spin 1 Sz 2 The magnitude of the total angular momentum J of the nucleus is also neatly quantized as p J j j 1 with quantized z-component Jz mj mj 0 1 2 j When A is even j is an integer but A is odd j is a half-integer Associated with the nuclear angular moment is a magnetic moment. In the case of a nucleus the quantity of magnetic moment is nuclear magneton eh Magnetic .
