复旦大学核科学与技术系 沈皓 haoshen@fudan.edu.cn Introduction to Nuclear Technology 复旦大学核科学与技术系 沈皓 haoshen@fudan.edu.cn

What Chapter 1. Introduction and Basic concepts Chapter 2. Radiation Chapter 3. Basic Instrumentation for Nuclear Technology Chapter 4. Power From Fission Chapter 5. Thermonuclear Fusion Chapter 6. Nuclear Weapons Chapter 7. Nuclear Waste Chapter 8. Radioactive isotopes and Their Applications Chapter 9. Nuclear Analysis Methods Chapter 10. Nuclear Technology in Industry and Agriculture Chapter 11. Medical Applications of Nuclear Technology Chapter 12. Impact, Issues and Future of Nuclear Technology

References 1) Fundamentals of Nuclear Science and Engineering, J.Kenneth Shultis and Richard E.Faw (Marcel Dekker) 2) Nuclear Physics - Principles and Applications, J.S.Lilley, (John Wiley & Sons, Ltd ) 3) Nuclear Technology, Joseph A. Angelo,Jr (Greenwood Press) 4) Nuclear Energy – Principles, Practices, and Prospects, David Bodansky (Springer) 5) Introduction to Nuclear Technology, Lecture notes by Chung Chieh

one’s work is performed honestly ! The Assessment Class discussion and home work 40% Midterm report 10% Final Exam 50% one’s work is performed honestly !

Chapter 1. Introduction and Basic concepts The Significance of Nuclear Technology Early Discoveries Basic Facts and Definitions 4.Units SI system, Physical constants, natural unit 5.Nuclear Reactions   Discovery of nuclear reactions (n.r.). Energy in n.r. Neutron induced nuclear reactions Simple theories or concepts related to n.r. Types of n.r. Applications of n.r.

Nature’s Hierarchy – a biological view 1.1 The Significance of Nuclear Technology 1)Widely applied Nature’s Hierarchy – a biological view ? ? ? Sub-Atomic Particles Atom Molecule Organelle Cell Tissue Organ Organ System Multicellular Organism Population Community Ecosystem Biosphere 6

Extensively Collaboration 1)Widely applied medicine, basic research, agriculture, industry, archaeology, geology, environmental science, and space exploration nuclear technology has played a dominant role in national security and geopolitics GDP 4.7% (USA) Extensively Collaboration

1.1 The Significance of Nuclear Technology 2) Alter the course of Human civilization Enrico Fermi nuclear reactor Started a new technical era human beings might wisely harvest the energy within the atomic nucleus in a controlled manner 1942 Prometheus stole fire from Mount Olympus control of fire ultimately enabled the human race to evolve into the technically complex global civilization

Pandora Box deliver misfortune into the house of man 05:29:45，J uly16，1945 Atomic Bomb - the age of nuclear weaponry. Human beings were capable of unleashing wholesale destruction on planet Earth Pandora Box deliver misfortune into the house of man

1.1 The Significance of Nuclear Technology 3) Skill and Wisdom how the technology works INNOVATION to make a unanimous decision to promote and harvest only the beneficial aspects of nuclear technology CAREFULNESS Instead of becoming the destroyer of worlds, nuclear technology should represent a powerful technology that serves as the saver of worlds and the protector of Earth CONSCIENCE

1.2 Early Discoveries

Democritus，atomos (ατομος), “not divisible.” Leucippus and Democritus (c. 460–c. 370 B.C.) The theory of atomism--The Four Elements Earth Air Fire Water Democritus，atomos (ατομος), “not divisible.”

1803, J.Dalton， suggested that each chemical element was composed of a particular type of atom. 1811, A.Avogadro, Avogadro’s Law. 1869, Mendeleev， the molecule as the smallest particle of any substance molecules, consisted of collections of atoms ？ Is an atom divisible

Dalton’s Atomic Theory Dalton (1766-1844 ): all substances are made of small, indivisible, and fundamental natural units called atoms. The law of partial pressure of gases: the pressure of a fixed volume of gases was proportional to the number of atoms present the pressure due to a particular gas is called the partial pressure. the partial pressure was the same as the pressure if the container has no other gas.

Molecules Failure of Dalton’s atomic theory 2 H + O = 2 HO 2 H + O = H2O (does not agree with volume measured) H + O = HO (does not agree with volume measured) Avogadro(1775-1856 ): natural units (for chemical reactions are molecules rather than single atoms. 1 vol. O2 + 2 vol. H2  2 vol. H2O 2 CO (g) + O2 (g) Avogadro’s number = 6.0221367e23 molecules mol-1 (physical constant)

penetrating rays could reveal the internal structure of opaque objects 1895 , Roentgen, X-ray Causing the sheet to glow was a penetrating form of radiation. He called this unknown radiation X-rays. penetrating rays could reveal the internal structure of opaque objects Crookes tube Dec.22, 1895

1896 , Becquerel, the discovery of radioactivity The uranium salt produced an intense silhouette of itself on the photographic plate

Marie and Pierre Curie 1898, named the emissions (alpha & beta) from uranium radioactivity Discovered the chemical elements radium and polonium

1897, Thomson, the discovery of electron Atom, was in fact divisible and contained “smaller parts.” “plum pudding”model the atom was a distributed positively charged mass with an appropriate number of tiny electrons embedded in it

1911, Rutherford, nuclear model of the atom a tiny central positive core that contained almost all the atom’s mass. The nucleus was surrounded by electrons in appropriate number to maintain a balance of electrical charge. "It was as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you."

Radioactivity Ernest Rutherford determined there were 3 kinds of radioactivity

1932, Chadwick discovered the neutron complete the basic model of the nuclear atom: a central, positively charged nucleus containing protons and neutrons that was surrounded by a discretely organized cloud of orbiting electrons. neutron-related nuclear research Famous persons http://www2.lucidcafe.com/lucidcafe/library/library.html#science

1. 人类寻找物质构造基本单元的历程

>10-2 cm(?) 10-8 cm 10 -12 cm 10-13 cm ? Nuclide Z N A Symbol 碳-12 6 12 12C 碳-13 7 13 13C 碳-14 8 14 14C

Atomic and Nuclear Stucture Atom - smallest unit of a chemical element Size on the order of 10-8 cm (1 Angstrom) Contains Z electrons (Qe = -1e, me = 0.511 MeV/c2) e = 1.602x10-19 Coulomb and Nucleus – Size on the order of 10-13 cm (1 Fermi ) Contains more than 99.9% of the mass of the atom Made of Z protons and N neutrons Proton (Qp = +1e, mp = 938.28 MeV/c2 ) Neutron (Qn = 0, mn = 939.57 MeV/c2 ) A = Atomic mass = Z + N Held together by strong nuclear force ZXN where X = chemical symbol  ~ 2.3  1014 g/cm3 A

Nobel Prizes in Nuclear Science

Chapter 1. Introduction and Basic concepts The Significance of Nuclear Technology Early Discoveries Basic Facts and Definitions 4.Units SI system, Physical constants, natural unit 5.Nuclear Reactions   Discovery of nuclear reactions (n.r.). Energy in n.r. Neutron induced nuclear reactions Simple theories or concepts related to n.r. Types of n.r. Applications of n.r.

1.3 Basic Facts and Definitions 1) The nucleus and its constituents

2) Nuclear Nomenclature Nuclide核素: a term used to refer to a particular atom or nucleus with a specific neutron number N and atomic (proton) number Z. Isotopes同位素: atoms of the same element with different number of neutron isobar同量异位素: nuclides with the same mass number A = N + Z but with different number of neutrons N and protons Z. Isotone同中子异位素: nuclides with the same number of neutrons N but different number of protons Z. isomer同质异能素 : the same nuclide (same Z and N) in which the nucleus is in different long lived excited states.

nuclear jargon Z N A Examples isotope Same D 1H 2H 3H isotone 2H 3He isobar 3H 3He isomer 99Te 99mTe

Calculation of Hydrogen Atomic Weight Isotope atomic mass Abundance atomic mass abundance 1H 1.00782503 0.99985 1.007674 2H 2.014102 0.000148 0.000298 3H 3.016049 Trace Atomic weight for H = 1.007674 + 0.00298 = 1.007972

一些放射性同位素 40K 1.28x108 a 39K (93.2%) 60Co 5.27 a 59Co 90Sr 28.8 a 88Sr 131I 8.04 d 137Cs 30.12 a 39K (93.2%) 59Co 88Sr 127I 133Cs Are the chemical properties of isotopes nearly identical?

Stable Nuclides Stable nuclides remain the same for an indefinite period. Some characteristics of stable nuclides: Atomic number Z  83, but no stable isotopes for Z = 43 and 61. There are 81 elements with 280 stable nuclides. Usually there are more neutrons than protons in the nuclei. Nuclides with magic number of protons or neutrons are very stable. Pairing of nucleons (spin coupling) contributes to nuclide stability. Is abundance of a nuclide related to its stability?

Stable Nuclides number of neutrons and protons Z = # of protons Find N / Z for 4He2 = 1 16O8 = 40Ar18 = 91Zn40 = 144Nd60 = 186Re75 = 209Bi83 = N = # of neutrons

Stable Nuclides N/Z of some light nuclides  Z Stable Nuclides | (Magic numbers and double magic-number nuclides are in bold) (to be continued) 21 Sc 20 . . . . . . . . . . . . . . . . . . . Ca Ca Ca Ca Ca Ca 19 K K K 18 Ar Ar Ar . 17 Cl Cl 16 S S S S 15 . . . . . . . . . . . . . . P 14 Si Si Si . . 13 Al 12 Mg Mg Mg . . . 11 Na 10 . . . . . . . . . . Ne Ne Ne 9 F . . . 8 O O O 7 N N 6 C C . . . . 5 . . . . B B 4 Be . . . . 3 Li Li 2 He He . . . . . 1 P D N 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Stable Nuclides N/Z of nuclides 40 Zr . . . . . . . . + . . . XXX X X 39 Y X 38 Sr X XXX 37 Rb X X 36 Kr X X XX X 35 Br . . . . . + . . X X 34 Se XXXX X X 33 As X 32 Ge X XXX X . 31 Ga X X 30 Zn . . . + . X XXX X . 29 Cu X X 28 Ni X XXX X . . 27 Co X 26 Fe X XXX . . 25 Mn + X 24 Cr X XXX . . 23 v XX 22 Ti XXXXX . . . 21 Sc X 20 Ca X X 2 2 3 4 5 01234567890123456789012345678901 N / A ratio increases as A increases More stable isotopes for even Z than odd Z More stable isotones for even N than odd N More stable isotopes and isotones for magic Z and N

Stable Nuclides natural occurring heavy nuclides Natural Occurring Isotopes of Heavy Elements (abundance) 76 Os 184 (0.018), 186 (1.59), 187 (1.64), 188 (13.3), 189 (16.1), 190 (26.4), 192 (41.0) 77 Ir 191 (38.5), 193 (61.5) 78 Pt 190 (0.0127), 192 (0.78), 194 (32.9), 195 (33.8), 196 (25.2), 198 (7.19) 79 Au 197 (100) 80 Hg 196 (0.146), 198 (10.02), 199 (16.84), 200(23.13), 201(13.22), 202(29.8), 204(6.85) 81 Tl 203 (29.5), 205 (70.5) 82 Pb 204 (1.4), 206 (25.1), 207 (21.7), 208 (52.3) 83 Bi 209 (100) 90 Th 232 (100% half life 1.4x1010 y) 92 U 235 (0.720, half life 7.04x108 y), 238 (99.276, half life 4.5x109 y)

Stable Nuclides pairing of nucleons Two protons or neutrons occupy a quantum state, due to their ½ spin. Pairing nucleons stabilises nuclides, leading to a large number of stable nuclides with even Z and N. No stable isotopes for Z = 43 or 61. No stable isotones with N = 19, 31, 35, 39, 61, 89 More stable isotopes for even Z than odd Z and for even N than odd N Elements with even Z are more abundant than those with odd Z of comparable mass. Effect of Paring Nucleons Z N # of stable stable nuclides even even 166 even odd 57 odd even 53 odd odd *4 total 280 *They are: 2D1, 6Li3, 10B5, & 14N7

Stable Nuclides magic numbers of nucleons Magic numbers are 2, 8, 20, 28, 50, 82, and 126. Double-magic number nuclides: 4He2, 16O8, 40Ca20, 48Ca20, & 208Pb82. 4He2 as alpha particles, abundant in the universe, 16O8 abundant on Earth. Six stable isotopes of Ca20, 5 stable isotopes of Ni28, high for their masses. Large number of stable isotopes and isotones with Z & N = 50 and 82. The heavies stable nuclide 209Bi83 has 126 neutrons. O8, Ca20, Ni28, Sn50 and Pb82 have relative high abundance.

3) Nuclear mass and energy The binding energy (BE) of a nuclide is the energy released when the atom is synthesized from the appropriate numbers of hydrogen atoms and neutrons. Z H + N n = AE + BE or Z mH + N mn = mE + BE where mH, mn, and mE are masses of H, n, and AE respectively. Eg BE = Z mH + N mn - mE BE (3He) = (2*1.007825 + 1.008665 - 3.01603) 931.481 MeV = 7.72 MeV BE (4He) = (2*1.007825 + 2*1.008665 - 4.00260) 931.481 MeV = 28.30 MeV The more the binding energy, the more stable is the nuclide.

Stable and Radioactive Nuclides average binding energy The binding energy and average binding energy of some nuclides Nuclide BE BE / A MeV MeV / nucleon 3He2 7.72 2.57 4He2 28.3 7.08 16O8 127.6 7.98 56Fe26 492.3 8.79 54Fe26 471.76 8.74 208Pb82 1636.44 7.87 238U92 1801.7 7.57 BE A A

The Average Binding Energy Curve

Stable and Radioactive Nuclides a semi-empirical equation for BE Instability due to p Pairing of nucleon Proportional to A BE(A,Z) = 14.1A - 13A2/3 - - + Ea Decrease due to surface tension Instability due to neutron to proton ratio

Stable and Radioactive Nuclides mass excess (ME) The difference between the mass of a nuclide and its mass number, A, is the mass excess (ME), ME = mass - A. Masses (amu) of some entities H 1.00782503 18O 17.99916 2D 2.014102 54Fe 54.938296 3H 3.016049 56Fe 55.934939 4He 4.002603 206Pb 205.975872 12C 12.000000 209Bi 208.9804 14C 14.003242 235U 235.043924 16O 15.994915 238U 238.055040 What are the MEs for the nuclides listed here? Which is the standard? Which have negative MEs?

Stable and Radioactive Nuclides mass excess (ME) and average -BE Comparison of mass excess and average binding energy (amu) Nuclide Mass ME -BE average BE H 1.007825 0.007825 0 0 n 1.008665 0.008665 0 0 3He 3.01603 0.01603 -0.00276 0.00828 4He 4.00260 0.00260 -0.0076 0.0304 12C 12.000000 0 -0.00825 0.09894 16O 15.994915 -0.005085 -0.00857 0.1369 40Ca 39.96259 -0.03741 -0.00917 0.3669 54Fe 53.939612 -0.060388 -0.00938 0.5065 56Fe 55.934939 -0.065061 -0.00944 0.52851 208Pb82 207.976627 -0.023373 -0.00845 1.757 238U92 238.050784 0.050784 -0.00813 1.934

Stable and Radioactive Nuclides fission and fusion energy and ME

Stable and Radioactive Nuclides application of mass excess (ME) Like masses, the ME can be used to calculate energy of decay, because the same scale is used for both. eg: ME’s of 40Sc21 and 40Ca20 are -20.527 and -34.847 MeV respectively. Estimate the energy of decay for 40Sc21  40Ca20 + b+ or 40Sc21 + e–  40Ca20 solution: Edecay = -20.527 - (-34.847) = 14.32 MeV Edecay includes 1.02 MeV for the positron-electron pair for b+ decay.

Chapter 1. Introduction and Basic concepts The Significance of Nuclear Technology Early Discoveries Basic Facts and Definitions 4.Units Grammar, SI system, Physical constants, natural unit 5.Nuclear Reactions   Discovery of nuclear reactions (n.r.). Energy in n.r. Neutron induced nuclear reactions Simple theories or concepts related to n.r. Types of n.r. Applications of n.r.

1.4 Units Grammar Capitalization Space plural A unit name is never capitalized even if it is a person's name. Thus curie, not Curie. However, the symbol or abbreviation of a unit named after a person is capitalized. Thus Sv, not sv. Use 58 m, not 58m . A symbol is never pluralized. Thus 8 N, not 8 Ns or 8 Ns .

raised dots Solidis mixing units/names prefix Sometimes a raised dot is used when combining units such as N.m2.s; however, a single space between unit symbols is preferred as in N m2 s. For simple unit combinations use g/cm3 or g cm-3. However, for more complex expressions, N m-2 s-1 is much clearer than N/m2/s. Never mix unit names and symbols. Thus kg/s, not kg/second or kilogram/s. Never use double prefixes such as μμg; use pg. Also put prefixes in the numerator. Thus km/s, not m/ms.

double vowels Hyphens numbers When spelling out prefixes with names that begin with a vowel, supress the ending vowel on the prefix. Thus megohm and kilohm, not megaohm and kiloohm. Do not put hyphens between unit names. Thus newton meter, not newton-meter. Also never use a hyphen with a prefix. Hence, write microgram not micro-gram. For numbers less than one, use 0.532 not .532. Use prefixes to avoid large numbers; thus 12.345 kg, not 12345 g. For numbers with more than 5 adjacent numerals, spaces are often used to group numerals into triplets; thus 123 456 789.123 456 33, not 123456789.12345633.

2) SI system "International System of Units“ (1) Base units (2) derived units which are combinations of the base units, (3) supplementary units (4) temporary units which are in widespread use for special applications. (5) Special Nuclear Units

(1) Base units Physical quantity length mass time electric current thermodynamic temperature luminous intensity quantity of substance Unit name meter kilogram second ampere kelvin candela mole Symbol m kg s A K cd mol

(2) derived units

(3) supplementary units

(4) special applications

(5) Special Nuclear Units The Electron Volt 1 eV= 1.602 176 46 x 10-19 J is the kinetic energy gained by an electron (mass me and charge -e) that is accelerated through a potential difference ΔV of one volt. The work done by the electric field is -eΔV = (1.60217646 x 10-19 C)(1 J/C) = 1.60217646 x 10-19 J = 1 eV. The Atomic Mass Unit 1 amu = 1.6605387 x 10-27 kg 1/12 the mass of a neutral ground-state atom of 12C.

3) Physical constants

4) Natural Units Units such as meter, second, joule, calorie, gram, kilogram etc are artificial (man-made) units. The fundamental components of materials are called the natural units. remain the same during changes Atoms, electrons, molecules, and moles are natural units or building blocks of matter. Photons are natural units of EM radiation (energy). Earth Water Cold Wet Dry Hot Fire Air

Chapter 1. Introduction and Basic concepts The Significance of Nuclear Technology Early Discoveries Basic Facts and Definitions 4.Units 5.Nuclear Reactions   Discovery of nuclear reactions (n.r.). Energy in n.r., Experimental Neutron induced nuclear reactions Simple theories or concepts related to n.r. Types of n.r. Applications of n.r.

She points it to the rock, and the rock turns into gold. - a legend 1.5 Nuclear Reactions Energy drives all reactions, physical, chemical, biological, and nuclear. Physical reactions change states of material among solids, liquids, gases, solutions. Molecules of substances remain the same. Chemical reactions change the molecules of substances, but identities of elements remain the same. Biological reactions are combinations of chemical and physical reactions. Nuclear reactions change the atomic nuclei and thus the identities of nuclides. They are accomplished by bombardment using subatomic particles or photons. 200Hg + 1H  197Au + 4He

Discoveries of Nuclear Reactions In 1914, Marsden and Rutehrford saw some thin tracks and spots among those due to a particles. They attributed them to protons and suggested the nuclear reaction: 14N + 4He  17O + 1H or 14N (a, p)17O F. Joliot and I. Curie discovered the reaction 27Al (a, n) 30P ( , b+ or EC) 30Si, half life of 30P is 2.5 min "the nitrogen atom is disintegrated under the intense force developed in a close collision with a swift particle". a and thin proton spots on fluorescence screen a source & tracks with long & thin proton track

Smashing the Atoms In 1929, John Cockroft and Ernest Walton used 700,000 voltage to accelerate protons and bombarded lithium to induce the reaction, 7Li + p  2  They called it smashing the atoms, a mile stone in the discovery of nuclear reaction. This reaction is also a proton induced fission, and illustrates the stability of the helium nuclide. They received the Nobel prize for physics in 1951. Use the discover of n.r. to explain n.r.

Nuclear Reactions changing the hearts of atoms Nuclear reactions, usually induced by subatomic particles a, change the energy states or number of nucleons of nuclides. After bombarded by a, the nuclide A emits a subatomic particle b, and changes into B. a + A  B + b or written as A (a,b) B b A (a,b) B a B A Describe nuclear reactions

Subatomic Particles for and from Nuclear Reactions Endothermic reactions require energy. Subatomic particles used to bombard or emitted in nuclear reactions: g photons b electrons p or 1H protons n neutrons d or 2D deuterons t or 3T tritons a or 4He alpha particles nE atomic nuclei exothermic reactions release energy.

Potential Energy of Nuclear Reactions Explain interaction of particle with nuclei

Estimate Energy in Nuclear Reactions The energy Q in a reaction A (a, b) B is evaluated according to ma + mA = mb + mB + Q, where mi means mass of i etc Q = ma + mA - (mb + mB) (difference in mass before and after the reaction) The Q is positive for exothermic (energy releasing at the expense of mass) or negative for endothermic (requiring energy) reactions. For endothermic reactions, the energy can be supplied in the form of kinetic energy of the incident particle. Energy appear as kinetic energy of the products in exothermic reactions.

Endothermic and Exothermic Reactions These two examples illustrate endothermic and exothermic reactions. Example: Energy for the reaction 14N + 4He ® 17O + 1H + Q 14.00307 + 4.00260 = 16.99914 + 1.007825 + Q Q = 14.00307 + 4.00260 – (16.99914 + 1.007825) = – 0.001295 amu = – 1.21 MeV endothermic, kinetic energy of a must be greater than 1.21 MeV Example: The energy Q for the reaction 11B(a, n) 14N, given masses: 11B, 11.00931; n, 1.0086649. Q = 11.00931 + 4.00260 - (1.0086649 + 14.00307) = 0.000175 amu = 0.163 MeV exothermic reaction

Nuclear Reaction Experiments Basic Components particle source target shield detectors data collection data analysis system

Neutron Sources for Nuclear Reactions Neutrons are the most important subatomic particles for inducing nuclear reactions. These sources are: Neutrons from a induced nuclear reactions Neutrons from g-photon excitations Neutrons from nuclear reactions induced by accelerated particles Neutrons from spontaneous and n-induced fission reactions (nuclear reactors) Know how to get neutrons

Neutrons from a Induced Reactions The discovery of neutron by James Chadwick in 1932 by reaction 9Be (a, n) 12C, was applied to supply neutrons for nuclear reactions by mixing a-emitting nuclides with Be and other light nuclides. Mixtures used as neutron sources Source Reaction n energy / MeV Ra & Be 9Be(a, n)12C up to 13 Po & Be 9Be(a, n)12C up to 11 Pu & B 11B(a, n)14N up to 6 Ra & Al 27Al (a, n)31P

Neutrons by g Excitation High-energy photons excites light nuclides to release neutrons. To avoid a- and b-ray excitation, radioactive materials are separated from these light nuclides in these two-component neutron sources to supply low energy neutrons for nuclear reactions. Two-component neutron sources Source Reaction n energy / MeV 226Ra, Be 9Be(g, n)12C 0.6 226Ra, D2O 2D(g, n)1H 0.1 24Na, Be 9Be(g, n)8Be 0.8 24Na, H 2D(g, n)1H 0.2

Neutrons from Accelerators and Reactors Neutrons are produced from nuclear reaction using energetic particles from accelerators. 2D (d, n) 3He 3T (d, n) 4He Neutrons from nuclear fission reactions 252Cf spontaneous fission to yield 3 or more neutrons 235U and 239 Pu induced fission reactions release 2 to 3 neutrons in each fission

Neutron Induced Radioactivity Using neutrons from the reaction, 27Al (a, n)31P, Fermi’s group in Italy soon discovered these reactions: 19F (n, ) 16N 27Al (n, ) 24Na ( , ) 24Mg. They soon learned that almost all elements became radioactive after the irradiation by neutrons, in particular 10B (n, ) 7Li releasing 2.3-2.8 MeV energy is used in classical neutron detectors. Now, detectors use, 3He (n, p) 3H Application of neutrons

Nuclear Reactions Induced by Cosmic Rays Cosmic rays consist of mainly high energy protons, and they interact with atmospheres to produce neutrons, protons, alpha particles and other subatomic particles. One particular reaction is the production of 14C, 14N(n, p)14C - b emitting, half-life 5730 y Ordinary carbon active in exchange with CO2 are radioactive with 15 disintegration per minute per gram of C. Applying decay kinetics led to the 14C-dating method.

Simple Theories on Nuclear Reactions Theories on nuclear reactions involve theory of nuclei, collision theory, and high-energy particles etc.We can only talk about some simple concepts of nuclear reactions. Energy Consideration of Nuclear Reactions Cross Sections of Nuclear Reactions Rate of Nuclear Reactions Types of Nuclear reactions Give an overall look at n.r.

Nuclear Reaction Cross Sections Cross section with unit barn (1 b=1e-28 m2) comes from target area consideration, but it is a parameter () indicating the probability leading to a reaction, rate =  N I (number per unit time) N is the number of target nuclei per unit area; I is the beam intensity Differentiate the concept and reality of cross section

Cross Sections and Rate A large copper (65Cu) foil with a surface density of 0.01g cm-2 is irradiated with a fast neutron beam with an intensity 2.0e10 n s-1 cm-2. A total width of the beam is 0.5 cm-2. After irradiation for 1 min, a total of 6.0e7 64Cu has been formed. Estimate the cross section for the reaction, 65Cu (n, 2n) 64Cu. Ignore the (t1/2 12.7 h) 64Cu nuclei decayed during the irradiation. Solution: ( rate =  N I ) rate = 6e7/60 =1e6 64Cu s-1. N = 6.022e23*0.01 cm-2*0.5 cm2/ 65 = 9.26e19 65Cu. 1e6 s-1 = s * 9.26e19 * 2.0e10 s-1 cm-2 s = 1.08e-24 cm2 = 1.08 b The cross section is 1.08 b for 65Cu (n, 2n) reaction.

Cross Sections and Rate The cross section for neutron capture of cobalt is 17 b. Estimate the rate of nuclear reaction when 1.0 g of 59Co is irradiated by neutrons with an intensity of 1.0e15 n s-1 cm-2 in a reactor. Solution: In a nuclear reactor, the entire sample is bathed in the neutron flux. N = 6.022e23 *1.0 / 59 = 1.02e22 59Co rate =  N I = 17e-24 * 1.02e22 * 1.0e15 = 1.74e14 60Co s-1 Estimate the radioactivity of 60Co, half life = 5.27 y. Theories of

Energy Dependence of Cross Section Cross sections depend on the nuclide, the reaction, and energy. The neutron capture cross sections usually decrease as energy of the neutron increase. The sharp increases are due to resonance absorption. Theories of

Cross Sections of Multi-reaction Modes Reactions of 4He and 209Bi serve as an example of multiple reaction modes. The variation of partial ss as functions of energy of 4He is shown to illustrate the point. stotal = S si for total consumption of nuclei.

Nuclear Fusion Cross Sections Cross sections data from reactions studied using particles from cyclotron 7Li (p, n) 7Be 3T (p, n) 3He 1H (t, n) 3He 2D (d, n) 3He 2D (t, n) 4He 3T (d, n) 4He

Types of Nuclear Reactions Elastic scattering (n, n) no energy transfer Inelastic scattering (n, n) energy transferred Capture reactions (n, g) Photon excitation (g, ) Rearrangement reactions (n, x) Fission reactions Fusion reactions Theories of

Elastic and Inelastic Scattering When the incident and emitted particles are the same, the process is scattering. If energy is transferred between the particle and the target nuclei the process is inelastic, otherwise, elastic. Elastic scattering example: 208Pb (n, n) 208Pb, but the two n’s may not be the same particle Inelastic scattering examples: 40Ca (a, a) 40mCa excitation 208Pb (12C, 12mC) 208mPb mutual excitation Types of

Capture Reactions The incident particle is retained by target nuclei in capture reactions. Prompt and delayed g emission usually follow. 197Au79 (p, g) 198Hg80 238U (n, g) 239U 2D (n, g) 3T 9Be (n, g) 10Be 12C (n, g) 13C 14N (n, g) 15N Types of

Rearrangement Nuclear Reactions After absorption of a particle, a nuclide rearranges its nucleons resulting in emitting another particle. For example: 197Au (p, d) 196mAu 4He (4He, p) 7Li 27Al (4He, n) 30P 54Fe (4He, 2 n) 56Ni 54Fe (4He, d) 58Co 54Fe (32S, 28Si) 58Ni

Some Nuclear Reactions Types of

Nuclear Fission and Fusion A nuclide splits into two pieces with the emission of some neutrons is nuclear fission. Nuclides such as 254Fm undergo spontaneous fission, whereas neutrons induce 238U and 239Pu fission. Fusion on the other hand combines two light nuclides into one, and may also be accompanied by the emission of one or more nucleons. An important fusion is 2D + 3T  4He + n

Applications of Nuclear Reactions Based on nuclide productions: synthesis of radioactive nuclides - for various applications synthesis of missing elements Tc, Pm and At synthesis of transuranium (93-102) elements synthesis of transactinide (103 and higher) elements Activation analyses non-destructive methods to determine types and amounts of elements Applications of

Syntheses of Radioactive Isotopes Over 1300 radioactive nuclides have been made by nuclear reactions. The most well known is the production of 60Co, by neutron capture, 59Co (100%) (n, g) 60mCo and 60Co - b and g emission t1/2 = 5.24 y The sodium isotope for study of Na transport and hypertension is produced by 23Na (n, g) 24Na (b emission, t1/2 = 15 h) For radioimmunoassay, 131I is prepared by 127I (n, ) 128I (b+, b- EC, t1/2 = 25 m) There are many other production methods. Applications of

Syntheses of Tc, Pm, and At In 1937, Perrier and Segré synthesized the missing element 43 using deuteron from cyclotron, 96Mo + 2D  97Tc + n, (Tc, EC, t1/2 = 2.6e6 y) In 1940, Segré and Mackenzie synthesized and named element 85 astatine ( Greek astatos - unstable) At by the reaction, 209Bi83 (, xn) (213-x)At85, (x = 1, 2, 3 etc) The missing element promethium was made by 144Sm62 (n, ) 145Sm ( , EC) 145Pm61 (EC, t1/2 = 17.7 y) Many more isotopes of these elements have been made. Applications of

Syntheses of Transuranium Elements From 1940 to 1962, about 11 radioactive transuranium elements (almost 100 nuclides) have been synthesized, about one every two years. Representative isotopes of the 11 elements are neptunium (Np93), plutonium (Pu94), americium (Am95), curium (Cm96), berklium (Bk97), californium (Cf98), einsteinium (Es99), fermium (Fm100), mendelevium (Md101), nobelium (No102), and lawrencium (Lw103). La57 , Ce, Pr59, Nd, Pm61, Sm, Eu63 , Gd, Tb65 , Dy, Ho67, Er, Tm69, Yb, Lu71 Ac89, Th, Pa91, U92, Np93 , Pu , Am95, Cm, Bk97, Cf, Es99, Fm, Md, No, Lw103 Among these, tons of 239Np, and its decay products 239Pu have been made for weapon and reactor fuel. Successive neutron capture reactions are major methods, but accelerators are involved. . . continue => Applications of

Syntheses of Transuranium Elements -continue Very heavy elements are synthesized using accelerated nuclides, 246Cm + 12C  254No102 + 4 n, 252Cf + 10B  247Lw103 + 5 n, 252Cf + 11B  247Lw103 + 6 n. These syntheses completed the analogous of rare-earth elements. These elements were made during the cold war, and results from the former USSR were not available to us. Applications of

Syntheses of Transactinide Elements 242Pu (22Ne, 4n) 260Rf104 rutherfordium 249Cf98 (12C6, 4n) 257Rf104 249Cf (15N, 4n) 260Ha105 hahnium 249Cf (18O, 4n) 263Sg106 seaborgium 268Mt109 ( , ) 264Ns107 nielsbohrium 209Bi (55Mn, n) 263Hs108 hassium 208Pb (58Fe, n) 265Hs108 272E111 ( , ) 268Mt109 meitnerium 208Pb (64Ni, n) 271Uun110 ununnilium 209Bi (64Ni, n) 272Uuu111 unununium Elements with Z > 103 are transactinides. Some results from both the USA and the former USSR are known, and some of the syntheses are given here. Applications of

Neutron Activation Analyses (NAA) Since most elements capture neutrons and produce radioactive isotopes, these reactions made them detectable. After b emission, the daughter nuclides usually emit g rays. Each nuclide has a unique g-ray spectra. Presence of their spectra after irradiation implies their being in the sample, and Intensities of certain peaks enable their amounts to be determined. NAA has many applications, and these will be discussed in Chapter 12. Applications of

Neutron Activation Analyses (NAA) NAA can be applied to explore planets and satellites and other objects in space. Applications of

Summary Discovery of nuclear rreactions (n.r.). Energy in n.r. Neutron induced nuclear reactions Simple theories or concepts related to n.r. Types of n.r. Applications of n.r.