The Physics of Energy sources Nuclear Fission


 Elfrieda Philomena Gilmore
 1 years ago
 Views:
Transcription
1 The Physics of Energy sources Nuclear Fission B. Maffei Nuclear Fission 1
2 Introduction! We saw previously from the Binding energy vs A curve that heavy nuclei (above A~120) will gain stability by splitting into 2 fragments of A~60 each! This reaction will release energy (Q) due to difference in binding energy between the parent nucleus and the products! The reaction will also produce neutrons! This has been observed in early fission experiments in the early 40s! The reaction will quite probably produce! rays A simple energy release model B/A energy for heavy nuclei (A~200) is about 7.6MeV B/A energy for more stable nuclei (fragments) ~ 8.5MeV The change of B/A is about 0.9MeV per nucleon If we have 235 U fission we have a release of energy Q=235x0.9MeV= 211.5MeV A typical nuclear fission releases an energy of the order of 200MeV Nuclear Fission 2
3 Mass partition 235 An typical example of fission is 236 * U + n! U! La+ Br + 2n It is not unique and many different mass partitions are possible as shown in figure. For 235 U fragment mass numbers vary between 70 and 160 with most probable values at about 96 and 135 Ref 2 Distribution of fission fragment masses from the fission of 235 U The energy released in process will be transmitted to the fragments as Kinetic energy Nuclear Fission 3
4 Neutron production Ref 2! The line of stability of the nuclei is not totally a straight line! There is a slight curvature leaning towards neutron rich nuclei when A increases! Ratio N/Z for A>200 is ~ 1.5 Uranium, Plutonium..! Ratio N/Z for 70<A<160 is These are the fragments When the fission of the heavy nucleus occurs, the fragments end up having the same neutron to proton ratio (~1.5) than the original nucleus. So compared to the line of stability for nuclei of their mass, these fragments are neutron rich. They will decay towards the line of stability mainly by "  emissions (long) but also by rapid shedding of several neutrons. These will be crucial to initiate other fission reactions! chain reaction Several fission reactions for the same original element! Average number of neutrons produced Nuclear Fission 4
5 Imagine a typical fission reaction Induced fission reaction Pu! Pd + Cd 3n The calculation of the Q factor will give 188MeV (in agreement with the rough estimate of 200MeV we saw earlier). From this figure we might think that fission is quite a probable process due to the energy released! so could it be spontaneous? Actually no: do not forget the Coulomb interaction! Coulomb barrier Let s assume that the 2 fragments are uniformly charged spheres of radius r pd and r cd We have the energy due to the Coulomb potential between the 2 fragments E coulomb = e2 Z Pd Z Cd 4"# 0 r r being the distance between them! Let s try to bring these 2 nuclei as close as possible to each other r = r Cd + r Pd = r 0 ( A 1/ 3 + A 1/ 3) Cd Pd Reminder: nucleus radius 1/3 r = r0 A, where r0 = 1.2fm Nuclear Fission 5
6 Induced fission reaction (2) Replacing all the parameters by their value we find (strongly recommended to do that as an exercise) c Bc = Ecoulomb = 270MeV B c : Coulomb barrier Coulomb Potential energy (1/r variation) distance We see that in order to be able to glue the 2 fragments together, we need to cross this energy barrier due to the Coulomb repulsion Only when the 2 nuclei will be close enough (basically coming in contact) the strong force will be able to overcome the repulsion and keep them together as one nucleus Attractive strong nuclear interaction Based on Ref 2 So working the other way round, in order to have a high probability of spontaneous fission of the parent nucleus, the energy Q that can be released during the fission should be comparable to the Coulomb barrier. It is not the case here Nuclear Fission 6
7 Induced fission reaction (3) Note: Spontaneous fission does exist Even with a low probability, it will occur statistically Occurs quantum mechanically by tunnelling effect Some very heavy isotopes are so instable that fission overcomes the Coulomb barrier We would need A large (~300) and roughly Z 2 /A>47 However for some isotopes spontaneous fission is a non negligible decay mode Example: 252 Cf is used as a radioisotope (spontaneous fission branch ratio~3%) More generally for fission reaction to happen, it needs to be induced (triggered) We need to excite the nucleus to above the Coulomb barrier That will happen through absorption of a neutron Having no charge, the neutron will not have to go through a Coulomb barrier in order to be absorbed by the nucleus The addition of the neutron will leave the resulting nucleus in an excited state 235 U + n! 236 U Nuclear Fission 7 *
8 Activation energy! The previous crude model was mainly to explain why fission needs to be induced.! However, in reality the necessary extra energy amount to make fission happen is not that large. This is what we call activation energy. Energy plot from our simple model of Pu fission 270 MeV Coulomb barrier 188 MeV Fission energy released Reference: Energy of 2 fragments far apart Equivalent to Energy state of Pu nucleus Graphs based on Ref 3 So to make sure that the reaction will occur (probability=1), the neutron needs to provide an energy at least equal to the activation energy Nuclear Fission 8
9 Activation energy: crude model to more realistic one! The actual activation energy is not as high as we did calculate! Mainly for heavy nuclei! Part of that can be explained with our simple liquid drop model n U 236 U * +n(s) Due to nucleus stretching, the overall binding energy of the nucleus has changed Consider the semiempirical mass formula from the LDM B(Z, A) = a v.a " a s.a 2 / 3 " a c.z(z "1) " a sym (A " 2Z)2 A 1/ 3 A +#(A,Z) When the nucleus is stretched, the volume is constant but the surface increases:! Volume term is! the same! Surface and Coulomb terms will be modified! Binding energy decreased (for more details see ref 3) Nuclear Fission 9
10 Variation of activation energy with mass number! In order to get a better value of the activation energies more detailed models are used taking into account more sophisticated effects than the LDM (i.e. shell model). Around Uranium 5MeV typically Z Dark curve: LDM Thin curve: shell structure model A~280 Spontaneous fission Figs based on Ref 3 Activation energy for heavy nuclei. A and Z dependence Nuclear Fission 10
11 235 U + n! 236 U * Application to uranium When 235 U captures a neutron to form a compound state 236 U * the excitation energy is: [ ] # c 2 Q ex = m( 236 U * ) " m( 236 U) Assuming the kinetic energy of the neutron small, the energy of the compound state 236 U * can be found directly by the mass energies of 235 U and the neutron:! 236 * 235 m( U ) = m( U ) + mn = ( u u) = u Q ex = ( u " )! 931.5MeV / u = 6. 5MeV The activation energy of 236 U is 6.2MeV! 235 U can be fissioned with zero energy neutron. Similar calculation for 238 U! 239 * + n U gives Q ex =4.8MeV Activation energy for 239 U is 6.6MeV. We need a neutron of at least ~2MeV to get fission. The difference between the excitation energies (6.5 and 4.8MeV) is one of the explanations for the extreme difference in the fissionability of 235 U and 238 U Nuclear Fission 11
12 Fission energy budget Example on thermalneutron induced fission of 235 U (all figures from ref 2) For this reaction, there is an average of 2.4 neutrons per fission! About 87% of the total energy is released promptly! 90% of this in fragments KE.! ~13% in radioactive decay! Electrons,! rays energy converted into heat! Neutrino energy not recoverable Mean energy of each released neutron ~ 2MeV Energy spectrum of emitted neutrons Nuclear Fission 12
13 Neutrons released We have seen that there is a prompt release of a few neutrons per reaction These prompt neutrons have a range of kinetic energy By convention we have the following designation:! Thermal: E ~ ev Delayed neutrons! Epithermal: E ~ 1 ev Timescale ~ 6sec! Slow: E ~ 1 kev! Fast: E ~ 100 kev to 10 MeV About 1% of released neutrons Other neutrons are emitted during some of the fission decay chains (from heavy fragments) These are released within about sec after fission About 99% of released neutrons Ex: sec Rb "! Sr! Sr + n 56 " Decay branch "  followed by neutron em. 1.4% probability Nuclear Fission 13
14 Cross section A brief explanation For a more precise development see references at the end Intensity I=#A Flux # Consider an incident flux of particles on a surface A of width dx (Number of particles/m 2 /sec) A Intensity (number of If N target nuclei are exposed to the beam (number of atoms in volume A.dx) incident particles per second) ="! A N = " N! dx! A dx $ N being the atoms volume density (Number/m 3 ) Let s suppose that we have a reaction (i.e. fission) between the incident particles and the atoms in the volume A.dx. If the nuclei in the target act independently, the reaction rate will be proportional to the number of incident particles (! # or I), and the number of atoms N.! = Rate R $ R " N $ N #! # dx # A#! event rateper nucleus incident flux The constant of proportionality is called the cross section % % is the reaction rate per target atom per unit of flux. It is equivalent to a probability of the process to occur. and R = " # N #! Note: % as units of area (cross section). R number of reaction per unit of time Nuclear Fission 14
15 A classical approach of the crosssection (but wrong!) R 1 R R 2 Consider the reaction 135 Xe + n! 136 Xe The neutron (radius R 1 ) can be captured by the nucleus of Xeon (radius R 2 ) when the strong interaction act! distance between their centres is * r! R = R 1 + R 2 Neglecting R 1 in comparison with R 2, R=R 2 Then a simple picture of the cross section would give: $ 2 2 2/3 = # " R = # " r0 " A!120fm 2 However, the cross section for this specific reaction is actually %~10 6 fm 2 The classic approach is not the right one. In order to get the real values of the crosssections a proper quantum mechanical treatment has to be perform and other physical processes have to be taken into account. Units: we use a more appropriate one for crosssection 1 barn=100 fm 2 = m 2 Nuclear Fission 15
16 Example Given 10g of natural uranium (mass u) and a neutron flux of cm 2 s 1, a thermal fission cross section of 235 U of 584b, find the fission rate. Fission rate = N%# with N being the number of 235 U atoms. Abundance of 235 U in natural uranium= 0.72% N = 10g! 6.023! ! = 1.82! atoms Fission rate = 1.82! 10 20! 10 13! 584! 10 " 24 = 1.06! reactions / sec Note: if several reactions are possible, each with a cross section % i, total cross section: " =! total " i i Nuclear Fission 16
17 Cross section data Thermal neutrons Fast neutrons Cross sections of neutron induced fission of 235 U and 238 U as a function of the incident neutron KE Note the poor cross section of 238 U Nuclear Fission Figures from Ref 3 17
18 What happens to the emitted neutron?! There is an average of & neutrons emitted per reaction! Not all emitted neutrons will be able to trigger another fission.! There are other reactions that enter in competition! Not all neutrons are useful in a chain reaction! Each competitive reaction has a probability to occur! Reaction rate 4 possible reactions: 3 competitors to fission 235 U + n# 236 U * elasticscattering """"" # 235 U + n Back to square one 236 U * inelastic scattering """"" # 235 U * + n Reemitted neutron as lower KE leaving 235 U in an excited state Scattering 236 U * radiative capture """"" # 236 U +! Heavy nucleus + low energy incident neutron: most probable decay Nuclear Fission 18
19 Fission vs capture! Each of the previous reactions has a corresponding cross section.! The cross sections are normalised: we can sum them!! fission elastic with +! +!! capture inelastic total =! =! a f =! +! =! e +! +! s c i =! absorption scattering =! =! In order to get a good fission rate, we want % fission to be the dominant cross section From previous plot we saw that the fission cross section of 235 U is strongly dependent of the incident neutron KE. % s is relatively independent of the energy ~ 10b % fission = 584b for thermal neutrons (~0.025eV) % fission ~ 1.5b for fast neutrons (~2MeV), ~1/6 of % s Fast neutrons (mean of 2MeV) are released during fission We need to slow them down to thermal energies to sustain chain reaction! Moderation Nuclear Fission 19 s a
20 Number of useful neutrons! Each 235 U fission reaction, initiated by a thermal neutron, produces an average of &=2.4 neutrons.! Some neutrons are lost through radiative capture both with 235 U and 238 U. Suppose that we have pure 235 U Let s call the number of released neutrons available to induce fission & a (also called! )! f " a = "! +! f c = 2.06 Suppose that we have natural uranium which contains 0.72% 235 U 235 & 0.72' ( f ( U) ) a = ) $ 235 $ % 0.72' ( a( U) ' ( c( 238 #! U)!" = % f % c % a % s 235 U U We can vary & a by changing the enrichment (proportion of 235 U in natural uranium) Note: an enrichment of 1.6% leads to & a = Nuclear Fission 20
21 Reactor kinetics! We introduce the neutron reproduction (or multiplication) factor k.! This is the ratio in number of neutron from one generation to the next.! Neutrons are characterised by a time constant ', mean time before absorption occurs! Includes the time necessary to moderate the neutron (106 s)! Includes a diffusion time at thermal energies before absorption (103 s) If there are N neutrons at time t, then there will be on average kn neutrons at time t+', k 2 N at time t+2' and so on. Then in a short time interval dt, the increase will be: dn = (kn " N) dt # Giving dn(t) N(t) dt = (k "1) #! $ N(t) = N 0 e (k "1)t # Nuclear Fission 21
22 Energy rate! The rate of energy released during fission will be: Q value per fission x number of absorbed neutrons leading to fission in time dt The integration gives de = Q " N(t) #! We then have 3 cases % dt = QN 0 exp ' & E = Q N 0" (k #1) (k $1)t # $ (k #1)t ' exp & ) + C st % " ( making ( * dt ) % E " exp ' & (k #1)t $! k<1 the number of neutrons decreases with time. The energy produced also decreases. Subcritical: the chain reaction will stop after a while! k~1 The number of neutron! remains constant, so is the produced energy. Critical: the chain reaction will be steadily sustained.! k>1 The number of neutrons and the energy will increase exponentially with time. Supercritical: we get a bomb ( * ) Nuclear Fission 22
23 References Ref 2: Lilley, J. Nuclear Physics Principles and Applications (Wiley 2006) Ref 3: Kenneth S. Krane, Introductory Nuclear Physics (Wiley 1988) Nuclear Fission 26
The Physics of Energy sources Nuclear Fission
The Physics of Energy sources Nuclear Fission B. Maffei Bruno.maffei@manchester.ac.uk Nuclear Fission 1 Introduction! We saw previously from the Binding energy vs A curve that heavy nuclei (above A~120)
More informationChapter 10. Nuclear Fission
Chapter 10 Nuclear Fission If we look again at the binding energies (per nucleon) for different nuclei, we note that the heavier nuclei have a smaller binding energy than those in the middle of the Periodic
More informationClassification of Neutron Interaction with Matter
Fission Process Page 1 Classification of Neutron Interaction with Matter Neutron Interaction Scattering Absorption Elastic Inelastic Fission Capture (n,γ) N. mult. (n,2n) (n,3n)... (n,p) (n,α) Fission
More informationENERGY RELEASE FROM FISSION
ENERGY RELEASE FROM FISSION DOEHDBK09/93 Atomic and Nuclear Physics ENERGY RELEASE FROM FISSION Fission of heavy nuclides converts a small amount of mass into an enormous amount of energy. The amount
More informationNEUTRON ACTIVATION ANALYSIS FUNDAMENTAL CONCEPTS
NEUTRON ACTIVATION ANALYSIS FUNDAMENTAL CONCEPTS Nucleus Nuclear Radiations Neutrons Classification Nuclear Reactions Neutron Reactions Neutron Sources Nuclear Reactor Schematic Neutron Flux Neutron Capture
More information10.) Fission and fusion
10.) Fission and fusion Fission (Lilley Chap.10) Average binding energy per nucleon: Nuclear fission: A A 1 + A 2 1 Fission barrier activation energy Example (Fission by capture of thermal neutrons) 235
More informationNuclear fission. Fission: what is it? The main steps toward nuclear energy How does fission work? Chain reactions
Nuclear fission Fission: what is it? The main steps toward nuclear energy How does fission work? Chain reactions What is nuclear fission? Nuclear fission is when a nucleus break into two or more nuclei.
More informationDr. J. Michael Doster Nuclear Engineering Department North Carolina State University
Introduction to Nuclear Reactions Dr. J. Michael Doster Nuclear Engineering Department North Carolina State University Nuclear Reactions Many types of nuclear reactions are possible and are usually represented
More informationChapter NP5. Nuclear Physics. Nuclear Reactions TABLE OF CONTENTS INTRODUCTION OBJECTIVES 1.0 NUCLEAR REACTIONS 2.0 NEUTRON INTERACTIONS
Chapter NP5 Nuclear Physics Nuclear Reactions TABLE OF CONTENTS INTRODUCTION OBJECTIVES 1.0 2.0 NEUTRON INTERACTIONS 2.1 ELASTIC SCATTERING 2.2 INELASTIC SCATTERING 2.3 RADIATIVE CAPTURE 2.4 PARTICLE
More informationThe Underlying Physics of Nuclear Energy Systems
The Underlying Physics of Nuclear Energy Systems John William Boldeman Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232. ABSTRACT There has been a great deal
More informationNUCLEAR FISSION DOEHDBK1019/193 Atomic and Nuclear Physics NUCLEAR FISSION
NUCLEAR FISSION DOEHDBK101/13 Atomic and Nuclear Physics NUCLEAR FISSION Nuclear fission is a process in which an atom splits and releases energy, fission products, and neutrons. The neutrons released
More informationAt the conclusion of this course the trainee will be able to:
NUCLEAR STABILITY AND INSTABILITY OBJECTIVES At the conclusion of this course the trainee will be able to: 1. Discuss the stability of nuclides in terms of neutron proton ratios and nuclear forces. 2.
More informationAnnouncements. Homework 9 due next Tuesday (now online). If you have not already done so, please also submit your paper through turnitin.
Tuesday, November 27th. Announcements. Homework 9 due next Tuesday (now online). If you have not already done so, please also submit your paper through turnitin. Lecture #221 In the news Lecture #222
More informationEnergy Devices Fission (Lecture 7)
Energy Devices Fission (Lecture 7) Eric R. Switzer (http://kicp.uchicago.edu/ switzer/) Nov. 14, 2009 Lecture outline: Orientation energies, mass, the nucleus. Fission, cross sections, moderation. CP1;
More information23  ATOMS, MOLECULES AND NUCLEI Page 1 ( Answers at the end of all questions )
23  ATOMS, MOLECULES AND NUCLEI Page ) If the radius of the 3 Al 27 nucleus is estimated to be 3.6 fermi, then the radius of 52 Te 25 nucleus will be nearly ( a ) 8 fermi ( b ) 6 fermi ( c ) 5 fermi (
More informationRADIOACTIVE DECAY. In this section, we describe radioactivity  how unstable nuclei can decay  and the laws governing radioactive decay.
ctivity BP RDIOCTIVE DECY Section 8: RDIOCTIVE DECY In this section, we describe radioactivity  how unstable nuclei can decay  and the laws governing radioactive decay. Radioactive Decay Naturally occurring
More informationMCRT L7: Neutron Transport
MCRT L7: Neutron Transport Recap fission, absorption, scattering, cross sections Fission products and secondary neutrons Slow and fast neutrons Energy spectrum of fission neutrons Nuclear reactor safety
More informationNuclear Fission. Nuclear and Radiation Physics, BAU, 1 st Semester, (Saed Dababneh).
Nuclear Fission Q for 235 U + n 236 U is 6.54478 MeV. Table 13.1 in Krane: Activation energy E A for 236 U 6.2 MeV (Liquid drop + shell) 235 U can be fissioned with zeroenergy neutrons. Q for 238 U +
More informationBasics of Nuclear Physics and Fission
Basics of Nuclear Physics and Fission A basic background in nuclear physics for those who want to start at the beginning. Some of the terms used in this factsheet can be found in IEER s online glossary.
More informationNuclear Physics. Nuclear Physics comprises the study of:
Nuclear Physics Nuclear Physics comprises the study of: The general properties of nuclei The particles contained in the nucleus The interaction between these particles Radioactivity and nuclear reactions
More informationa) Conservation of Mass states that mass cannot be created or destroyed. b) Conservation of Energy states that energy cannot be created or destroyed.
7 Fission In 1939 Hahn and Strassman, while bombarding U235 nuclei with neutrons, discovered that sometimes U235 splits into two nuclei of medium mass. There are two important results: 1. Energy is produced.
More informationNuclear Physics. Lecture 8
Nuclear SubAtomic and Physics Particle Nuclear Physics Lecture 8 3 rd Year Junior Honours Course Dr Daniel Watts Main points of lecture 9 Shell model successful in predicting ground state spins and parities
More informationHypothesis on the formation of copper in a nickelhydrogen reactor
Hypothesis on the formation of copper in a nickelhydrogen reactor By Daniel Gendron 23 rd of january, 2014 Document issued from French video YouTube Claude Thiébaut 2 th September.2015 Content of this
More informationNUCLEAR CROSS SECTIONS AND NEUTRON FLUX
To determine the frequency of neutron interactions, it is necessary to describe the availability of neutrons to cause interaction and the probability of a neutron interacting with material. The availability
More informationD. increases exponentially with time. (1)
. A sample of radioactive carbon4 decays into a stable isotope of nitrogen. As the carbon4 decays, the rate at which the amount of nitrogen is produced A. decreases linearly with time. B. increases linearly
More informationThe Physics of Energy sources Nuclear Reactor Practicalities
The Physics of Energy sources Nuclear Reactor Practicalities B. Maffei Bruno.maffei@manchester.ac.uk www.jb.man.ac.uk/~bm Nuclear Reactor 1 Commonalities between reactors All reactors will have the same
More informationNuclear reactions, nuclear energetics
Lecture 2 Nuclear reactions, nuclear energetics SS2011: Introduction to Nuclear and Particle Physics, Part 2 2 1 Nuclear fission  history 1932 The English physicist James Chadwick discovered the neutron
More informationGeneral Physical Science. Symbols of the Elements. Symbols of the Elements. Chapter 10 Nuclear Physics. Symbol notation
General Physical Science Chapter 10 Nuclear Physics Symbols of the Elements Symbol notation Introduced by Berzelius Based on the Latin name Symbols now based on the English name First letter capitalized,
More informationChapter 6: Neutron Slowing Down Part I
Chapter 6: Neutron Slowing Down Part I 4.1. Introduction In thermal reactors, in order to achieve criticality, we want to slow the fission neutrons down to thermal energies. As seen in a previous lecture,
More informationNuclear Binding & Stability. Stanley Yen TRIUMF
Nuclear Binding & Stability Stanley Yen TRIUMF From last time: Electron scattering allows us to measure the charge density distribution of a nucleus, by measuring the diffraction pattern. We assume that
More informationor just by u. b) 1 amu = X kg c) The energy equivalence of 1 amu is 1 amu = 931 MeV Discovery of Neutrons:
CBSE Class12 Physics Quick Revision Notes Chapter13: Nuclei tomic Number: The number of protons in the nucleus is called the atomic number. It is denoted by. Mass number: The total number of protons
More information............... [2] At the time of purchase of a Strontium90 source, the activity is 3.7 10 6 Bq.
1 Strontium90 decays with the emission of a βparticle to form Yttrium90. The reaction is represented by the equation 90 38 The decay constant is 0.025 year 1. 90 39 0 1 Sr Y + e + 0.55 MeV. (a) Suggest,
More informationChapter 9. Writing a Balanced Nuclear Equation
Chapter 9 The Nucleus, Radioactivity and Nuclear Medicine 3 December 213 Writing a Balanced Nuclear Equation Nuclear equation used to represent nuclear change In a nuclear equation, you do not balance
More informationPhysics Notes for Class 12 Chapter 13 Nuclei
1 P a g e Physics Notes for Class 12 Chapter 13 Nuclei Nucleus The entire positive charge and nearly the entire mass of atom is concentrated in a very small space called the nucleus of an atom. The nucleus
More informationRadioactivity III: Measurement of Half Life.
PHY 192 Half Life 1 Radioactivity III: Measurement of Half Life. Introduction This experiment will once again use the apparatus of the first experiment, this time to measure radiation intensity as a function
More informationThe nucleus. How big is a nucleus? How big is a nucleus? Class 40. Nuclear Radiations. A table of masses. The atomic mass unit. The atomic mass unit
uclear Radiations The nucleus A nucleus consists of protons and neutrons; these are known as nucleons. Each nucleus is characterized by two numbers: A, the atomic mass number (the total number of nucleons);
More informationNuclear and Particle Physics  Lecture 25 Nuclear Fusion
1 Introduction Nuclear and Particle Physics  Lecture 2 Nuclear Fusion We have seen from the binding energy per nucleon curve that nuclei at A above 6 26Fe can split and release energy e.g. through alpha
More informationENERGY FROM STARS (2012;1)
ATOMS: NUCLEUS QUESTIONS ENERGY FROM STARS (2012;1) Use the information in the table and the graph to answer the following questions. i. In the above list, nickel and iron have the highest binding energy
More informationIntroduction to Nuclear Decays
Introduction to Nuclear Decays 1 The valley of stability N=Z Magic numbers Valley of stability (location of stable nuclei) Z=82 (Lead) Z=50 (Tin) Z=28 (Nickel) Const A cut Z=20 (Calcium) Z=4 (Helium) Z=8
More informationAP Chemistry Chapter 18  The Nucleus: A Chemist s View
AP Chemistry Chapter 8  The Nucleus: A Chemist s View 8. Nuclear Stability and Radioactive Decay A. Radioactive Decay. Decomposition forming a different nucleus and producing one or more particles a.
More informationA sample laboratory report ARTIFICIAL RADIOACTIVITY
A sample laboratory report Experiment No. 8 ARTIFICIAL RADIOACTIVITY Name of the student: Date the experiment was performed: Objective of the experiment Test the exponential law of radioactive decay, measure
More informationMasses in Atomic Units
Nuclear Composition  the forces binding protons and neutrons in the nucleus are much stronger (binding energy of MeV) than the forces binding electrons to the atom (binding energy of ev)  the constituents
More information427.006 FISSION. At the conclusion of this lesson the trainee will be able to:
FISSION OBJECTIVES At the conclusion of this lesson the trainee will be able to: 1. Explain where the energy released by fission comes from (mass to energy conversion). 2. Write a typical fission reaction.
More informationR.A. Chaplin Department of Chemical Engineering, University of New Brunswick, Canada
NUCLEAR REACTOR THEORY R.A. Chaplin Department of Chemical Engineering, University of New Brunswick, Canada Keywords: Nuclear Physics, Nuclear Energy, Neutrons, Nuclear Reactors Contents 1. Nuclear Physics
More information
dx Inside well (E>V): Outside well (E
PH300 Modern Physics SP11 I am one of those who think like Nobel, that humanity will draw more good than evil from new discoveries. Marie Curie Recently: 1. Schrödinger equation, free particle. Square
More informationChapter 24. Radioactivity and such
Chapter 24 Radioactivity and such Radioactivity emit radiation Nuclear reactions change an element into a new element!! Lots of energy involved! Unlike a chemical reaction because we are doing more than
More informationBasic Nuclear Concepts
Section 7: In this section, we present a basic description of atomic nuclei, the stored energy contained within them, their occurrence and stability Basic Nuclear Concepts EARLY DISCOVERIES [see also Section
More informationToday s lecture: Radioactivity
Today s lecture: Radioactivity radioactive decay mean life half life decay modes branching ratio sequential decay measurement of the transition rate radioactive dating techniques Radioactive decay spontaneous
More informationChem 481 Lecture Material 4/17/09
Chem 481 Lecture Material 4/17/09 Nuclear Reactors A controlled, selfsustaining fission chain reaction is the source of enormous energy in a nuclear reactor. Recall that the energy release when a large
More informationObjectives 404 CHAPTER 9 RADIATION
Objectives Explain the difference between isotopes of the same element. Describe the force that holds nucleons together. Explain the relationship between mass and energy according to Einstein s theory
More informationIn a medical electron accelerator installation, electrons and photons are the
Chapter 1. THE HAZARD DEFINED Neutron Production In a medical electron accelerator installation, electrons and photons are the particles intentionally produced in order to destroy cancerous cells, thus
More informationAn isotope notation is written as, where X is the, A is the (sum of protons and neutrons), and Z is the.
Unit 3: Nuclear Chemistry Notes Name Review: Isotope notation An isotope notation is written as, where X is the, A is the (sum of protons and neutrons), and Z is the. For example 238 92U U is for, mass
More informationNuclear Fission. Nuclear Reactor Theory, BAU, Second Semester, (Saed Dababneh).
Nuclear Fission Recoverable energy release 200 MeV per 235 U fission. Fission rate = 2.7x10 21 P fissions per day. P in MW. 3.12x10 16 fissions per second per MW, or 1.2x105 gram of 235 U per second per
More informationNuclear Reactions chap.31. Fission vs. fusion mass defect..e=mc 2 Binding energy..e=mc 2 Alpha, beta, gamma oh my!
Nuclear Reactions chap.31 Fission vs. fusion mass defect..e=mc 2 Binding energy..e=mc 2 Alpha, beta, gamma oh my! Definitions A nucleon is a general term to denote a nuclear particle  that is, either
More informationFinal Exam Review Questions. 2. Calculate the Qvalues for all of the reactions listed in problem 1 in addition to
Final Exam Review Questions Chapter 1: 1. Complete the following reactions 60 a. Co?+ 0? 1e 7 b. 3 Li+ 1 1 H?+ 4 2 He 10 c. Be+ 4 5 2He?+ 1 1 H 9 d.? Be+ 4 2 He?+ 2 1 H 2. Calculate the Qvalues for all
More informationAlgebrabased Physics II
Algebrabased Physics II Dec. 3 rd : Radioactivity Chap 31 Nuclear Physics and How to find nuclear binding energy? How to calculate radius of a nucleus? How to identify different radioactive decay? How
More informationExam Review: Topic 07 Nuclear Physics Practice Test: 33 marks (43 minutes) Additional Problem: 31 marks (46 minutes)
Practice Test: 33 marks (43 minutes) Additional Problem: 3 marks (46 minutes). Which of the following causes the greatest number of ionizations as it passes through cm of air? (The total energy of the
More informationEnergymomentum relation (That Famous Equation..)
Energymomentum relation (That Famous Equation..) Energy: E =! u mc Momentum: p =! u mu Squaring and subtracting the second equation from the first: # E! p c = m c 4 " 1! u u % $ c Energymomentum relation:
More informationSince binding energy differs for different nuclei, can release or absorb energy when nuclei either fuse or fission.
Nuclear processes in stars Mass of nuclei with several protons and / or neutrons does not exactly equal mass of the constituents  slightly smaller because of the binding energy of the nucleus. Since binding
More informationMain properties of atoms and nucleus
Main properties of atoms and nucleus. Atom Structure.... Structure of Nuclei... 3. Definition of Isotopes... 4. Energy Characteristics of Nuclei... 5. Laws of Radioactive Nuclei Transformation... 3. Atom
More informationPart 1: Basic Radiation Physics
Introduction Part : Basic Radiation Physics Nuclear Medicine Physics for Technologists Fall 2008 Radiation: Energy propagated through space in the form of waves or particles. Examples of Radiation: Radiowaves
More informationPreview of Period 10: Nuclear Reactions
Preview of Period 0: Nuclear Reactions 0. Rates of Radioactive Decay How can the halflife of a radioactive source be used to find the age of the source? How can capacitor discharge be used to model radioactive
More information3. Which of these nuclear reactions is possible? (Conserve charge & baryon number)
The final exam will consist of 40 multiple choice questions plus five other questions model on (or taken from) the homework. The 40 multiple choice questions will contain about 20 questions from Chapts
More informationA4. An example of alpha decay is given by the following reaction:
SECTION 10: Alpha Decay Alpha decay involves the emission of a 4 He nucleus from a heavy element, represented by the generic equation A Z 4 He + A4 2 Z2 X Y + Q. (Eq. 61) Note that the chemical states
More informationNuclear Decay. Chapter 20: The Nucleus: A Chemist s View. Nuclear Decay. Nuclear Decay. Nuclear Decay. Nuclear Decay
Big Idea: Changes in the nucleus of an atom can result in the ejection of particles, the transformation of the atom into another element, and the release of energy. 1 Chapter 20: The Nucleus: A Chemist
More informationChapter 10: Nuclear Reactions
Chapter 0: Nuclear Reactions Goals of Period 0 Section 0.: To describe the halflife of nuclei and radiocarbon dating Section 0.: To further explore the relationship between mass and energy Section 0.3:
More informationGeneral Physics (PHY 2140)
General Physics (PHY 2140) Lecture 36 Modern Physics Nuclear Physics Nuclear properties Binding energy Radioactivity http://www.physics.wayne.edu/~apetrov/phy2140/ Chapter 29 1 Lightning Review Last lecture:
More informationNuclear Chemistry. Chapter 19. Copyright The McGrawHill Companies, Inc. Permission required for reproduction or display.
Nuclear Chemistry Chapter 19 Copyright The McGrawHill Companies, Inc. Permission required for reproduction or display. 1 Chemical Processes vs. Nuclear Processes Chemical reactions involve changes in
More informationNuclear Decays. Alpha Decay
Nuclear Decays The first evidence of radioactivity was a photographic plate, wrapped in black paper and placed under a piece of uranium salt by Henri Becquerel on February 26, 1896. Like many events in
More informationNuclear Instability and Why Nuclei Decay
Nuclear Instability and Why Nuclei Decay Properties of an Atom An atom is made up of a positively charged nucleus and negatively charged electrons held together by the coulomb force, the same force that
More informationDO PHYSICS ONLINE FROM QUANTA TO QUARKS THE NUCLEUS OF AN ATOM
DO PHYSICS ONLINE FROM QUANTA TO QUARKS THE NUCLEUS OF AN ATOM Models of the atom J J Thompson model of the atom (1907) plumpudding model: positive charge uniformly distributed over a sphere of radius
More informationNuclear Reactions Fission And Fusion
Nuclear Reactions Fission And Fusion Describe and give an example of artificial (induced) transmutation Construct and complete nuclear reaction equations Artificial transmutation is the changing or manipulation
More informationFast electrons and positrons (beta rays) Photons (gamma rays) Heavy charged particles (protons, alpha rays,...) Neutrons
1 Many processes represented by GamBet, such as the emission of bremsstrahlung photons and Compton electrons, involve interactions with atomic electrons. Particle emission may also follow from reactions
More informationOutline. Neutron Interactions and Dosimetry. Introduction. Tissue composition. Neutron kinetic energy. Neutron kinetic energy.
Outline Neutron Interactions and Dosimetry Chapter 16 F.A. Attix, Introduction to Radiological Physics and Radiation Dosimetry Neutron dosimetry Thermal neutrons Intermediateenergy neutrons Fast neutrons
More information14  NUCLEUS Page 1. same different examples. Z A and N Carbon  6C 12, 6C 13 and 6 C 14 Uranium  92 U 233, 92U 235 and 92 U 238
14.1 Nucleus  General Information 14  NUCLEUS Page 1 A nucleus consists of electrically neutral neutrons and positively charged protons. The nucleus of hydrogen has only one proton and no neutrons. The
More informationPart II Particle and Nuclear Physics Examples Sheet 3
Part II Particle and Nuclear Physics Examples Sheet 3 T. Potter Lent/Easter Terms 017 Basic Nuclear Properties 9. (B) The SemiEmpirical mass formula (SEMF) for nuclear masses may be written in the form
More informationnot to be republished NCERT NUCLEI Chapter Thirteen MCQ I
Chapter Thirteen NUCLEI MCQ I 131 Suppose we consider a large number of containers each containing initially 10000 atoms of a radioactive material with a half life of 1 year After 1 year, (a) all the containers
More informationRadioisotopes in Soil
Radioisotopes in Soil Helmut Fischer, June 2003 Introduction Radioisotopes are of interest in environmental physics for several reasons:  environmental protection  the emitted radiation is potentially
More information18 Homework: Reading, M&F, ch. 22, pp Problems: Nakon, ch.21, #15, 9, 11, 12, 14, 16. M&F, ch. 22, #21, 23, 29, 45, 53, 61, 63.
th 18 Homework: Reading, M&F, ch. 22, pp. 878911. Problems: Nakon, ch.21, #15, 9, 11,, 14, 16. M&F, ch. 22, #21, 23, 29, 45, 53, 61, 63. XI. Nuclear Chemistry. Not chemistry in the normal sense, because
More informationdiscovered by Rutherford discovered by Chadwick Nucleus contains protons and neutrons. Nucleon: any particle in the nucleus (p +, n o )
Proton: p + Neutron: n o discovered by Rutherford discovered by Chadwick Nucleus contains protons and neutrons. Nucleon: any particle in the nucleus (p +, n o ) Protons, neutrons, and electrons account
More informationRadioactive decay and half life. Lecture 25
Radioactive decay and half life Lecture 25 www.physics.uoguelph.ca/~pgarrett/teaching.html Review of L24 Fluorescence Property of some atoms or molecules to absorb light at a particular wavelength and
More informationStructure of the nucleus
Structure of the nucleus A bit of History ~400 BC: Greek Philosopher Democritus believed that each kind of matter could be subdivided into smaller and smaller bits until one reached the very limit beyond
More informationChemistry: Nuclear Reactions Guided Inquiry
Chemistry: Nuclear Reactions Guided Inquiry Nuclear reactions change the nucleus of an atom. Chemical Reactions vs. Nuclear Reactions Atoms and molecules are striving to achieve the most stable arrangement.
More informationNuclear Chemistry. Radioactivity. Patterns of Nuclear Stability. Patterns of Nuclear Stability. Nuclear Equations
Nuclear Chemistry Nucleons: particles in the nucleus: p + : proton Nuclear Equations n : neutron. Mass number: the number of p + + n. Atomic number: the number of p +. Isotopes: have the same number of
More informationCHAPTER 25 NUCLEAR CHEMISTRY
CHAPTER 25 NUCLEAR CHEMISTRY 25.1 Nuclear Radiation Standard 11c  many naturally occurring isotopes of elements are radioactive, as are isotopes formed in nuclear reactions. Standard 11d  the three
More informationLecture 23. Applications. Radiocarbon Dating Nuclear Fission Medical Imaging
Lecture 23. Applications Radiocarbon Dating Nuclear Fission Medical Imaging ConcepTest 30.1 The Nucleus There are 82 protons in a lead nucleus. Why doesn t the lead nucleus burst apart? 1) Coulomb repulsive
More informationPhys102 Lecture 34/35 Nuclear Physics and Radioactivity
Phys102 Lecture 34/35 Nuclear Physics and Radioactivity Key Points Structure and Properties of the Nucleus Alpha, Beta and Gamma Decays References SFU Ed: 421,2,3,4,5,6,7. 6 th Ed: 301,2,3,4,5,6,7. Atomic
More informationII. NeutronNucleus Interactions
II. NeutronNucleus Interactions Introduction The main goal of this course is to develop an understanding of how reactors behave and the skills to quantify their behavior. We know that reactor behavior
More informationPhysics of the Nucleus
From the Last Time Superconductor = zeroresistance material Critical temperature Critical current Critical magnetic field  no superconductivity outside of critical ranges Superconductor types Type I
More informationChapter NP3. Nuclear Physics. Decay Modes and Decay Rates TABLE OF CONTENTS INTRODUCTION OBJECTIVES 1.0 RADIOACTIVE DECAY
Chapter NP3 Nuclear Physics Decay Modes and Decay Rates TABLE OF CONTENTS INTRODUCTION OBJECTIVES 1.0 RADIOACTIVE DECAY 1.1 ALPHA DECAY 1.2 BETA MINUS DECAY 1.3 GAMMA EMISSION 1.4 ELECTRON CAPTURE/BETA
More informationChapter 20: The Nucleus: A Chemist s View
Chapter 20: The Nucleus: A Chemist s View Big Idea: Changes in the nucleus of an atom can result in the ejection of particles, the transformation of the atom into another element, and the release of energy.
More informationConceptual Physics Review (Chapters 3840)
Conceptual Physics Review (Chapters 3840) Chapter 38 Give two examples of models for light. Describe the photoelectric effect, and explain which model of light it supports. Explain what the atomic spectrum
More informationNEUTRON INTERACTIONS
(Notes 7) NEUTRON INTERACTIONS 1. Introduction The neutron is indirectly ionizing like the photon It is unstable when free and beta decays to the proton with an 11.7 m halflife. Unlike the photon, interactions
More informationINTERACTION OF RADIATION WITH MATTER
Different types of radiation interact with matter in widely different ways. A large, massive, charged alpha particle cannot penetrate a piece of paper and even has a limited range in dry air. A neutrino,
More informationChapter NP2. Nuclear Physics NUCLEAR STABILITY CONCEPTS TABLE OF CONTENTS INTRODUCTION OBJECTIVES 1.0 NUCLEAR STABILITY 2.0 TYPES OF RADIATION
Chapter NP2 Nuclear Physics NUCLEAR STABILITY CONCEPTS TABLE OF CONTENTS INTRODUCTION OBJECTIVES 1.0 NUCLEAR STABILITY 2.0 TYPES OF RADIATION 2.1 ALPHA PARTICLES 2.2 BETA PARTICLES 2.3 GAMMA RAYS 2.4
More informationMODES OF RADIOACTIVE DECAY
MODES OF RADIOACTIVE DECAY DOEHDBK1019/193 Atomic and Nuclear Physics MODES OF RADIOACTIVE DECAY Most atoms found in nature are stable and do not emit particles or energy that change form over time.
More informationClass Structure and Properties of the Nucleus. Nucleus is made of protons and neutrons Proton has positive charge:
Class 33 30.1 Structure and Properties of the Nucleus Nucleus is made of protons and neutrons Proton has positive charge: Neutron is electrically neutral: 1 30.1 Structure and Properties of the Nucleus
More informationChapter 25 Nuclear Chemistry
Chapter 25 Nuclear Chemistry Isotope Examples Prob: An atom of Kr has a mass of 94 AMU. How many protons & neutrons does it have? Answer: Kr = element #36 (36 protons). Neutrons = mass  protons, = 9436
More information