By shadia M.S.Elayyat

Out Line #Introduction #Objective # Review - Radiation - Alpha particle(  ) - beta particle(  ) - gamma particle (  ) - Half - life - Radioactive Decay Series # Nuclear Reaction - Definition - Notation - Conservation law - Example - Type # Application - Nuclear reactor # References

1895 : Wilehelm Roentgen found invisible rays were emitted when electrons bombarded certain materials : Henri Becquerel discovered that a sample of a uranium compound gave off “ionizing radiation.” 1919 :Rutherford convert the nitrogen nuclei into oxygen nuclei by using alpha particle (first nuclear reaction experiment ). Introduction / History

The main objectives of this research are : - Study the nuclear radiation and nuclear reaction - Calculate the energy (Q- value) - Complete the nuclear reaction equation - Study the application of nuclear reactor Objective

-- Radiation comes from the nucleus of an atom. -- Certain isotopes of atoms are radioactive. Others are stable. Examples: ** C-12 (6p & 6n) Very stable ** C-14 (6p & 8n) Will emit a beta particle to become nitrogen( unstable). Radioactivity is the spontaneous emission of particles or energy from an atomic nucleus as it disintegrates. Radiation   

Table(1): Difference between alpha, beta and gamma particle

Radiation particles in electromagnetic field Figure (1): radiation particle in electromagnetic field

In magnetic field Radiation passing through a magnetic field shows that massive, positively charged alpha particles are deflected one way, and less massive beta particles with their negative charge are greatly deflected in the opposite direction. Gamma rays, like light, are not deflected. In electric field An alpha particle will therefore accelerate towards the negative plate and the beta particle towards the positive plate. The gamma ray has no charge so it is not affected by the electric field and will just continue on its straight path.

Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus. Alpha decay equation Example Alpha particle (  ) 

Decay energy (Q) Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation, this energy called decay energy(Q). Where : Mass of mother nucleus Mass of daughter nucleus Mass of alpha particle Positive Negative

From conservation energy law Rearrange equation From the conservation of momentum

SoSo

Example Calculate the Q and KE ???

Beta particle :high-energy, high- speed electrons or positrons emitted by certain types of radioactive nuclei Beta decay equations Example Beta particle (  ) 

High energy photon Gamma decay equation Example Gamma particle (  )

Half-life (t ½ ) is the time required for a quantity to fall to half its origin value. Half Life Where : N 0 is the initial quantity of the substance N(t) is the quantity that still remains λ is a positive number called the decay constant t is the time

Figure (2): number of remaining particles as a function of time

Table (2): Half – Life for some particle Half lifeSymbol d 12.7 h 1.84 Sec

Example Half – Life =4 sec Initial quantity = 3 g How much would remain after 20 Sec??? Solution

Radioactive Decay Series

Figure (3): Half – live time for uranium(238) decay sires

Radioactive Decay Series –Radioactive decay produces a simpler and more stable nucleus. –A radioactive decay series occurs as a nucleus disintegrates and achieves a more stable nuclei –There are 3 naturally occurring radioactive decay series. Thorium 232 ending in lead 208 Uranium 235 ending in lead 207 Uranium 238 ending in lead 206

Example : Find n and b??? Solution By using conservation of A 92 = 82+8X2+bX-1 => b=6

Nuclear reaction : process in which two nuclei collide to produce one or more nuclides that are different from the origin nuclide. Rutherford Experiment (1919) Nuclear reaction

What is the difference between chemical reaction and nuclear reaction ?? # in chemical reaction The nucleus remains unchanged ((sharing or transfer of electrons # in nuclear reaction the nucleus will be changed Nuclear Reaction Vs. Chemical Reaction

Table 3: difference between chemical reaction and nuclear reaction

Nuclear reaction can be written as a+ X  Y+ b Where a: accelerated projectile X : the target Y : reaction product ( heavy product ) b : reaction product ( light product ) Nuclear reaction notation

Instead of writing the full form we can use the compact form X(a,b) Y = a+ X-> Y+ b Symbols to Remember Table 4: nuclear symbols

Nuclear reaction conditions 1- Conservation of energy 2- Conservation of linear momentum 3- Conservation of a total charge 4- Conservation of mass number 5-Conservation of spin 6- Conservation of leptons number 7- Conservation of Baryons number Conserva tion law

Example 31 15

Type Nuclear reaction Fissi on Fusi on joining of nuclei splitting of nuclei splitting of nuclei

Nuclear Fission FigureFigure (4): Nuclear Fission reaction

** Nuclear fission is either a nuclear reaction or a radioactive decay process in which the heavy nucleus of a particle splits into lighter nuclei. ** It produce - free neutrons - Photons ( gamma rays ) - large amount of energy **A fission reaction typically happens when a neutron hits a nucleus with enough energy to make the nucleus unstable Small changes of mass = huge changes in energy

Example ev May be any nuclei obey conservatio n rule Un – stable uranium 236 Stable uranium 235

OR

Energy released on nuclear reaction Calculate Q value ??? for atomMass (amu ) High energy

Chain Reaction Figure (5): Nuclear chain reaction

A chain reaction is a sequence of reactions where a reactive product causes additional reactions to take place Uranium reaction The neutrons released in the induced reaction can then trigger more reactions on other uranium-235 atoms. This chain reaction can quickly get out of control.

Nuclear Fusion FigureFigure (6): Nuclear Fusion Reaction

Fusion reaction is a nuclear reaction that bines, two smaller nuclei into a larger nucleus. It is difficult to make fusion reactions occur because positively charged nuclei repel each other.(heat to Nuclear fusion is the source of the energy from the Sun and other stars.

Example

Applicatio n Nuclear reactor Figure (7): nuclear reactor

Nuclear reactor structure 1- Steam Generator 2- Control Rods 3- Pressurizer 4- Reactor vessel 5- Turbine 6- Condenser 7- Moderator 8- Coolant

Nuclear reactor work The fission process creates heat that produces steam in a secondary water system. The steam turns a turbine-generator which produces electricity.

Exercises Q1:- Complete the following nuclear equation ??

Q2:- When a heavy element like Uranium decays to a lighter element like Thorium, what do we call it? A: Fusion B: Fission C: Transmogrification D: Uranicide

Q3:- The half life of I-123 is 13 hr. How much of a 64 mg sample of I-123 is left after 26 hours?

1-Alfred Theodore Goble, David K. Baker,” Elements of modern physics”, Ronald Press Co.378(1971). 2-Elmer E. Lewis, “Fundamentals of Nuclear Reactor physics”, Academic Press,7(2008). 3-S. K. Rajput,” Nuclear Energy”, Pinnacle Technology, (2009). 4-Bill W. Tillery,” Introduction to physics and chemistry: foundations of physical science”, Wm. C. Brown Publishers,334 (1992). 5- Samuels M.S.Wong,” Introductory of nuclear physics “, John Wily &Son, (2004). Referenc e

6- adioact/Radio/deflection_fields.htm6- adioact/Radio/deflection_fields.htm xperiments/ex7.html