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**Basic Nuclear Properties**

Static nuclear properties (Time-independent): Electric charge, radius, mass, binding energy, angular momentum, parity, magnetic dipole moment, electric quadrupole moment, energies of excited states. Dynamic properties (Time-dependent): Self-induced (Radioactive decay). Forced (Nuclear reactions) cross sections. The key: Interaction between individual nucleons. Excited states: atomic intervals ~ eV. nuclear intervals ~ 104 – 106 eV. Decays and reactions: Conservation laws and selection rules. HWc 2 Where to find nuclear data??? Nuclear and Radiation Physics, BAU, Second Semester, (Saed Dababneh).

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**Nuclear Mass (Introduction)**

Unified atomic mass unit u based on 12C. Replaced both physical and chemical amu based on 16O and natural oxygen, respectively (Find conversion factors). 1 u = M(12C)/12 = ……… kg = …………… MeV/c2. Rest masses u MeV/c kg electron ………… …………… ……… proton ………… …………… ……… neutron ………… …………… ……… 12C …………… ……… Avogadro’s number .. !! What is the number of atoms in 1 kg of pure 238U? Mass Stability. E = mc2. Tendency towards lower energy Radioactivity. Neutron heavier than proton “Free” neutron decays (T½ = ???): Nuclear and Radiation Physics, BAU, Second Semester, (Saed Dababneh).

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**Nuclear Mass (Introduction)**

Nuclear masses measured to high accuracy: mass spectrograph. energy measurement in nuclear reactions. Mass decrement = difference between actual mass and mass number: Δ = m – A Δ of parent(s) > Δ of product(s) radioactivity. Binding Energy? Stability? Fission? Fusion? More later …….. Mass doublet method. Usually atomic masses are tabulated. Mass of the atom < ZmH + Nmn. Nuclear and Radiation Physics, BAU, Second Semester, (Saed Dababneh).

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**The Valley of Stability**

Nuclear and Radiation Physics, BAU, Second Semester, (Saed Dababneh).

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**Nuclear Size Depends on probe and relevant physics.**

Different experiments give different results Radius not well defined. Depends on probe and relevant physics. Probes should be close to the order of the size of the nucleus ~ m. Visible light? much larger. 1 MeV ? = ?? x m. Interacts with orbital electrons. Suitable probes: p, n, , e .... Charge distribution. Mass distribution. All experiments agree qualitatively and somehow quantitatively. Project …. R A⅓ R = r0 A⅓ with r0 dependent on the method. Matter distribution charge distribution. [Recently some halo nuclei, e.g. 11Li, found]. What is that? Nuclear and Radiation Physics, BAU, Second Semester, (Saed Dababneh).

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**Nuclear Size HW 4 HWc 3 Experiments show that**

t = (2.4 ± 0.3) fm for all nuclei t/R A-1/3 Is surface effect the same for all nuclei? HWc 3 Compare for A = 4, 40, 120 and 235. 0 = nucleon density near the center. t = “skin” thickness. a = thickness parameter. R = Half-density radius. Nuclear and Radiation Physics, BAU, Second Semester, (Saed Dababneh).

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**Nuclear Size Why? R A⅓ 0 decreases with A? No Yes**

High-energy e scattering Light nuclei? From some experiments….! Charge distribution: r0 = 1.07 fm. a = 0.55 fm. Matter distribution: r0 = 1.25 fm. a = 0.65 fm. Why? Nuclear and Radiation Physics, BAU, Second Semester, (Saed Dababneh).

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**Nuclear Size 40Ca ….. ….. 59Co ….. ….. 115In ….. ….. 197Au ….. …..**

HW 5 Nucleus Z/A Charge density 40Ca … ….. 59Co … ….. 115In … ….. 197Au … ….. Charge radius ~ nuclear radius, even though heavy nuclei have more neutrons than protons. Explain… Density of ordinary atomic matter ~ 103 kg/m3. Density of nuclear matter ~ 1017 kg/m3. Neutron stars, 3 solar masses, only 10 km across ….. !!! Surface effect? Nuclear and Radiation Physics, BAU, Second Semester, (Saed Dababneh).

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**Short range of nuclear force**

Nuclear Size Three conclusions can be drawn: Inside the nucleus the density is fairly uniform. The transitional surface layer is thin. The central density has a similar value for different nuclei. Liquid Drop Short range of nuclear force Saturation? Get an estimate for nuclear density and thus inter-nucleon distance. Nuclear and Radiation Physics, BAU, Second Semester, (Saed Dababneh).

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**Nuclear Size HW 6 How can we get r0 from the graph?**

1 Ci Pu-Be Neutron Source Neutron Detector Absorber Beam From Optical Model Dimensions Different targets HW 6 How can we get r0 from the graph? Preferably low Nuclear and Radiation Physics, BAU, Second Semester, (Saed Dababneh).

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Controlled Fission 235U + n X + Y + (~2.4)n

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