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Nuclear Physics Signatures

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Nuclear Physics Signatures Nuclear Physics Signatures Fukushima Daiichi March 11, 2011 I, daughter of Xerxes, the great King. I am Ruduamna! (518-465 BC) discovered in Balochistan in 2000 Persian princess Ruduamna daughter of Xerxes? Awan princess Hika Munshi of Balochistan? Persian princess Khor-ul-Gayan daughter of Kuroosh al-Kabir (Cyrus the Great, the King of Kings)? Egyptian princess? Robert Koenig, Science 292, 2417 (2001) W. Kretschmer et al., NIM 223, 672 (2004) 1.3. Basic Principles of Nuclear Physics Nucleus consists of: Z protons with e+ charge N neutrons with no charge. A Mass number A=Z+N protons & neutrons are bound by strong force: R10-13 m Isotope, Isobar, Isotone Isotopes: nuclei with Z=constant, N varies! Isotones: nuclei with N=constant, Z varies! Isobars: nuclei with A=constant, Z,N varies! hydrogen isotopes: Z=1 Z Nuclear Chart Isotope Isobar http://www.nndc.bnl.gov/chart/ Isotone N Nuclear Masses & Energetics The mass M of the nucleus is smaller than the mass of its proton and neutron constituents! 2 2 2 M · c < Z mp · c + N mn · c Z=3 protons E=m·c2 N=3 neutrons The mass difference is the binding energy B The binding energy is the energy that needed to dissociate a nucleus into its single constituents. It is released when N neutrons and Z protons fusion together to form a nucleus with the mass number A! Nuclear Binding Energy B/A=B/(Z+N) Example: What is the binding energy of the oxygen isotope 18O? -24 mp= 1.007596 · 1.66 · 10 g -24 mn= 1.008486 · 1.66 · 10 g M(18O) = 17.99916 · 1.66 · 10-24 g Z=8, N=10, A=18 B = (Z · m + N · m - M) · c2 p n B(18O) = 1.382 · 105 keV = 2.21·10-11 J B(18O)/A=1.23·10-12 J 1g 18O contains 7.41·1011 J (W·s) Atomic Mass Unit: 1 amu=1/12(M12C)=1.66 · 10-24 g Math and Units kg m2 1 J 1 s2 1eV 1.60221019 J A g 6.0221023 particles c 300000 km / s 1 amu 1.661027 kg 931.49 MeV / c2 http://en.wikipedia.org/wiki/Electronvolt Nuclear Reaction Processes In a nuclear reaction two nuclei combine forming a third nucleus! The total number of protons and neutrons remains constant! 17O+n 18O; 17N+p18O; N=9+1N=10; N=10+0N=10; Z=8+0Z=8; Z=7+1Z=8; The third nucleus is called compound nucleus. It either decays by -emission to ground state or breaks up by particle emission into a light particle component (e.g. ) and a rest nucleus (14C). 17O(n,)18O capture reaction 17N(p,)18O 17O(n,)14C transfer reaction 17N(p,)14C charge exchange 17N(p,n)17O Reaction Q-values • Mass difference between initial particles and final particles is called: Q-value (energy) • If a reaction needs energy to take place it is called: Endothermic (Q<0) • If a reaction releases energy when taking place it is called: Exothermic (Q>0) 2 A(a,b)B (mA+ma-mB-mb)·c =Q http://ie.lbl.gov/toimass.html a (p, n, ) http://nucleardata.nuclear.lu.se/database/masses/ A (17N, 17O, 14C) 12000 10000 Logarithmic Scale 8000 6000 A logarithmic scale is a scale of data that 4000 N N log(N) displays the value of a physical quantity 2000 1 1.00E+00 0.0 using decadal intervals corresponding to 2 2.00E+00 0.3 orders of magnitude, rather than a standard 0 3 3.00E+00 0.5 1 2 3 4 5 6 7 8 9 1011121314151617 linear scale. 5 5.00E+00 0.7 10000 10 1.00E+01 1.0 A simple example is a chart whose vertical 20 2.00E+01 1.3 or horizontal axis has equally spaced 1000 30 3.00E+01 1.5 increments that are labeled 1, 10, 100, 1000, 50 5.00E+01 1.7 instead of 0, 1, 2, 3. Each unit increase on 100 100 1.00E+02 2.0 the logarithmic scale thus represents an 200 2.00E+02 2.3 10 300 3.00E+02 2.5 exponential increase in the underlying 500 5.00E+02 2.7 quantity for the given base (10, in this case). 1 1 2 3 4 5 6 7 8 9 1011121314151617 1000 1.00E+03 3.0 Presentation of data on a logarithmic scale 2000 2.00E+03 3.3 can be helpful when the data covers a large 4.5 3000 3.00E+03 3.5 range of values. The use of the logarithms 4.0 5000 5.00E+03 3.7 3.5 of the values rather than the actual values 10000 1.00E+04 4.0 3.0 reduces a wide range to a more manageable 2.5 size. Some of our senses operate in a 2.0 logarithmic fashion (Weber–Fechner law), 1.5 1.0 which makes logarithmic scales for these 0.5 input quantities especially appropriate. 0.0 1 2 3 4 5 6 7 8 9 1011121314151617.
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