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.

1896 : 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

() HeYX A

ZAZ

42

42

HeThU 42

23490

23892

HeRnRa 42

21986

22388

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 :

2)( cMMMQ dm

dMmM

M

Mass of mother nucleus

Mass of daughter nucleus

Mass of alpha particle

Positive

Negative

From conservation energy law

fi EE

KEcMKEcMcM ddm 222

KEKEcMMM ddm 2)(Rearrange

equation

dKEKEQ

22

2

1

2

1ddvMvMQ

From the conservation of momentum

vM

MvvMvM

dddd )(

)](1[2

1 2

dM

MvMQ

)](1[dM

MKEQ

][

MM

MQKE

d

d

)(][dd

d M

MKE

MM

MQKE

So

Example Calculate the Q and

KE???

HeThU 42

23490

23892

238.05079

234.04363

4.00262)0026.404363.23405079.238( cQ

MevamucQ 25.400456.0 2

MevKE 18.4]0026.404363.234

04363.234[25.4

U23892

Th23490

He42

Beta particle :high-energy, high-speed electrons or positrons emitted by certain types of radioactive nucleiBeta decay equations

Example

Beta particle ()

eA

ZAZ veYX

1

eA

ZAZ veYX

1

evepn_

01

11

10

evenp 01

10

11

High energy photonGamma decay equation

Example

Gamma particle ()

XX AZ

AZ

*

_*12

6125 eveCB

CC 126

*126

Half-life (t½) is the time required for a quantity to fall to half its origin

value.

Half Life

teNtN 0)(

Where : N0 is the initial quantity of the substanceN(t) is the quantity that still remainsλ is a positive number called the decay constantt is the time

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

693.0

2/1 t 693.0

2/1 t

Table (2): Half – Life for some particle

Half life Symbol

14.28 d

12.7 h

1.84 Sec

U23892

U23592

P3215

Cu6429

Kr9236

y81004.7

y91047.4

Example Half – Life =4 sec Initial quantity = 3 gHow much would remain after

20 Sec???

Solution 1

2/1

sec173.04

693.0693.0 t

20173.00 3)( eeNtN t

g0942.0

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 A92 = 82+8X2+bX-1 => b=6

bnPbU 20682

23892

84

206238

A

AAn NO

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

*189

147

42 FNHe

HOF 11

178

*189

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

Chemical

Reactions

Mass is conser

ved (doesn

’t change

)

Small energy change

s

No changes in the nuclei

Nuclear

Reactions

Small change

s in mass

Huge energy change

s

protons, neutrons, electrons

and gamma rays can be

lost or gained

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 conditions1 -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

Conservation

law

Example

nPAlHe 10

3015

2713

42

31

15

TypeNuclear reaction

Fission

Fusion

joining of nuclei

splitting of nuclei

Nuclear Fission

Figure( 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

neutronsYXUUn *23692

23592

10

0.04 ev

May be any nuclei obey conservation rule

Un – stable uranium

236

Stable uranium

235

nKrBaUUn 10

9236

14156

*23692

23592

10 3

nSrXeUUn 10

9438

14054

*23692

23592

10 2

nBrLaUUn 10

8735

14857

*23692

23592

10

OR

OR

Energy released on nuclear reaction

Calculate Q value ??? for

nSrXeUn 10

9438

14054

23592

10 2

atom Mass (amu )

235.0439

139.9054

93.9054

U23592

Xe14054

Sr9438

2}]2{}[{ CmmmmmQ nSrXeUn

2}]00867.129063.939054.139{}0439.23500867.1[{ CQ

22235.0 camuQ

MevQ 2.2085.9312235.0

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

Figure( 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.

K1010

ExampleMevnHeHH 6.171

042

31

21

MevHHHH 411

31

21

21

Application Nuclear

reactor

Figure (7): nuclear reactor

Nuclear reactor structure

1 -Steam Generator 2 -Control Rods

3 -Pressurizer 4 -Reactor vessel

5 -Turbine 6 -Condenser7 -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??

.......* XX AZ

AZ

............11 eP

....3015

2713

42 PAlHe

....4019

4020 evKCa

Q2-:

When a heavy element like Uranium decaysto a lighter element like Thorium, what dowe call it?

A: FusionB: FissionC: TransmogrificationD: 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,143-151(2004).

Reference

6-http://www.cyberphysics.co.uk/topics/radioact/Radio/deflection_fields.htm

.

7-http://en.wikipedia.org/wiki/Half-life

8-http://www.blackcatsystems.com/GM/experiments/ex7.html