This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: What you should know about ... Nuclear Physics 1. Nuclei and strong interaction [Q12,Q13] nuclear notation: Z protons and A total nucleons = A Z X ; size: r = r A 1 / 3 , with r 1 . 2fm Strong interaction between color neutral objects (such as nucleons) is short range ( < 2fm) Binding energy: E b = ( parts E parts ) E sys Mass defect: m = ( parts m parts ) m sys = E b /c 2 = Zm H + Nm n m atom binding energy formula ( A > 20): E b ( A,Z ) = a I A a S A 2 / 3 a C Z 2 /A 1 / 3 a A ( A 2 Z ) 2 /A with a I = 15 . 56MeV, a S = 17 . 23MeV, a C = 0 . 697MeV, a A = 23 . 285MeV binding energy per nucleon, e b = E b /A and binding energy vs. mass ( E = mc 2 ) 2. Radioactive decay (beta, alpha, gamma) [Q13,Q14] Predicting stability and type of decay: energy level diagrams, binding energy formula, atomic mass beta:  = n p + + e + e + = p + n + e + + e EC = p + + e n + e alpha: helium nuclei (2 protons, 2 neutrons) gamma: photons from decays of excited nuclear states activity  dN/dt = N = solution: N ( t ) = N e t = halflife t 1 / 2 = ln2 / Z stable ( A ) for stability against decay: Z stable = A 1 . 0084 2+0 . 015 A 2 / 3 . This formula gives the stable isotope for evenodd nuclei ( A is odd) or eveneven nuclei (both Z stable and N are even). For oddodd nuclei ( A even, N,Z stable odd) the neighboring eveneven nuclei may have lower atomic mass, in which case the stable nuclei have Z = Z stable 1....
View
Full
Document
 Spring '11
 Furnstahl
 Physics, Quantum Physics

Click to edit the document details