matriculation physics nuclear reaction

8/12/2019 Matriculation Physics Nuclear Reaction

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PHYSICS CHAPTER 14

Bombardmen t Bombardmen t

wi th energe tic wi th energe tic

par ticlespar ticles

Nuclear Nuclear

fusionf usion

Nuclear Nuclear

f issionf ission

CHAPTER 14: Nuclear reactionCHAPTER 14: Nuclear reaction

(2 Hours)(2 Hours)

Four types ofFour types ofnuclear reaction:nuclear reaction:

is defined as ais defined as a

physical processphysical process

in which there is ain which there is achange in identitychange in identity

of an atomicof an atomic

nucleusnucleus.

Radioac ti vRadioac ti v

e deca ye deca y



PHYSICS CHAPTER 14

2

At the end of this chapter, students should be able to:At the end of this chapter, students should be able to:

StateState the conservation of charge (the conservation of charge ( Z Z and nucleon and nucleon

number (number ( A A in a nuclear reaction! in a nuclear reaction! "rite and complete"rite and complete the e#uation of nuclear reaction!the e#uation of nuclear reaction!

$alculate$alculate the energy liberated in the process of nuclearthe energy liberated in the process of nuclear

reactionreaction

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14.1 Nuclear reaction (1 #our)



PHYSICS CHAPTER 14

3

'!'!' $onservation of nuclear reaction An% nuclear reaction !ust o'e%e$ conseration laws state$

'elow:

Conseration o relatiistic ener*% (inetic an$ restener*ies):

Conseration o linear !o!entu!:

Conseration o an*ular !o!entu!:

'!' Nuclear reaction

=energyicrelativistreaction before∑ energyicrelativist

reactionafter∑

=momentumlinearreaction before∑

momentumlinearreactionafter∑

=momentumangularreaction before∑ momentumangular

reactionafter∑



PHYSICS CHAPTER 14

4

Conseration o c#ar*e (ato!ic nu!'er Z ):

Conseration o !ass nu!'er A:

Howeer+ it is er% #ar$ to o'e% all t#e conseration laws.

= Anumbermass

reaction before∑ Anumbermass

reactionafter∑

= Z numberatomicreaction before∑ Z numberatomicreactionafter∑

Note:Note:

T#e !ost importantimportant o conservation lawsconservation laws s#oul$ 'e obeyedobeyed '% eer% nuclear reaction are conservation of chargeconservation of charge (atomicatomic

number number )an$ o mass number mass number .



PHYSICS CHAPTER 14

5

Ener*% is release$ (li'erate$) in a nuclear reaction in t#e or! o

)inetic energy of the particle emitted)inetic energy of the particle emitted+ t#e )inetic energy of)inetic energy of

the daughter nucleusthe daughter nucleus an$ t#e energy of the gamma*rayenergy of the gamma*ray

photonphoton t#at !a% acco!"an% t#e reaction.

T#e ener*% is calle$ t#e reaction ,R $isinte*ration ener*% (Q).

It !a% 'e calculate$ '% in$in* t#e !ass $eect o t#e reactionw#ere

T#e reaction ener*% Q is t#e ener*% e-uialent to t#e !ass

$eect ∆ m o t#e reaction+ t#us

'!'!+ Reaction energy (Q

( ) 2Δ cmQ =

− nucleusof massreactionafter products∑ =defectMass

nucleusof massreaction before∑

f i mmm −=∆ ('!'('!'

('!+

('!+

Speed of light in vacuumSpeed of light in vacuum



PHYSICS CHAPTER 14

6

is $eine$ as the phenomenon in which an unstable nucleusthe phenomenon in which an unstable nucleus

disintegrates to ac#uire a more stable nucleus withoutdisintegrates to ac#uire a more stable nucleus without

absorb an eternal energyabsorb an eternal energy.

T#e disintegration is spontaneousdisintegration is spontaneous an$ !ost co!!onl%

inoles t#e e!ission o an al"#a "article (α ,R )+ a

'eta "article (β ,R ) an$ *a!!ara% (γ ,R ). It

also release an ener*% Q nown as disintegration energydisintegration energy.

'!'!- Radioactivity decay

Note:Note:

I t#e alue omm ,R

QQ is positivepositive+ t#e reaction is calle$

eothermic (eoergiceothermic (eoergic in w#ic# t#e energy releasedenergy released in t#eor! t#e inetic ener*% o t#e "ro$uct.

I t#e alue o mm ,R QQ is ne*atie+ t#e reaction is calle$

endothermic (endoergicendothermic (endoergic in w#ic# t#e energy need to beenergy need to be

absorbedabsorbed or t#e reaction occurre$.

He42

γ00

e0

1−



PHYSICS CHAPTER 14

7

Poloniu! nucleus $eca%s '% al"#a e!ission to lea$ nucleus can 'e

re"resente$ '% t#e e-uation 'elow:

Calculate

a. t#e ener*% Q release$ in /e0.

'. t#e waelen*t# o t#e *a!!ara% "ro$uce$.

(ien !ass o Po212+ mPo211.35 u 6 !ass o P'27+

mPb278.38994 u an$ !ass o α "article + m

α4.7729 u)

Solution :Solution :

Ea!"le 1 :

Q++→ HePbPo42

20882

21284

Q++→ HePbPo42

20882

21284

beforebefore

decaydecayafterafter

decaydecay

α $eca%

∑∑ = f i Z Z ∑∑ = f i A Aan$



PHYSICS CHAPTER 14

8


a. T#e !ass $eect ($ierence) o t#e reaction is *ien '%

T#e ener*% release$ in t#e $eca% reaction can 'e calculate$ '%

usin* two !et#o$:

''stst method:method:

f i mmm −=∆( )αmmm +−= PbPo

( )0026.4!664.20!888".211 +−=u1061. #−×=∆m

( )( )2!# 1066.11061. −− ××=∆m$g10""#.1 2−×=

$g10661u1 2!−×= .

( )( )282 1000.#10""#.1 ××= −Q

%104#6.112−

×=Q

( ) 2cmQ ∆=in )gin )g



PHYSICS CHAPTER 14

9


a. T#us t#e ener*% release$ in /e0 is

++ndnd

method:method:

Me&8.8=Q

1#

12

1060.1

104#6.1−−

××=Q

%10601Me&1 1#−×= .

( )2

cmQ ∆=

Me&".8=Q

22

u1

Me&'".#1c

cm

∆=

2

Me&'".#1u1 c=in uin u

( ) 22

#

u1

Me&'".#1u1061. c

c

×= −



PHYSICS CHAPTER 14

10


'. T#e reaction ener*% Q is release$ in or! o *a!!ara% w#ere

its waelen*t# can 'e calculate$ '% a""l%in* t#e Planc;s

-uantu! t#eor%:Q

hc E ==

λ

Q

hc

=λ

( )( )12

8#4

104#6.1

1000.#106#.6−

−

×××

=

m10#.1 1#−×=λ Note:Note:

T#e radioactive decay only occurredradioactive decay only occurred w#en t#e alue o mm

,R QQ is positivepositive.



PHYSICS CHAPTER 14

11

A nicel99 nucleus $eca%s to a new nucleus '% e!ittin* a

'eta "article.

a. <rite an e-uation to re"resent t#e nuclear reaction.

'. I t#e new nucleus oun$ in "art (a) #as t#e ato!ic !ass o

95.324 u an$ t#e ato!ic !ass or nicel99 is 95.3231 u+ w#at

is t#e !ai!u! inetic ener*% o t#e e!itte$ electron=(ien !ass o electron+ m

e 5.43 × 17−4 u an$ c >.77 × 17 ! s−1)


a. Nuclear reaction e-uation !ust o'e% t#e conseration o ato!ic

nu!'er an$ t#e conseration o !ass nu!'er.

Ea!"le 2 :

Q++→ − e( )i 01

662

6628 β $eca%

( ) )i66

28



PHYSICS CHAPTER 14

12


'. ien

T#e !ass $eect ($ierence) o t#e reaction is *ien '%

I t#e reaction ener*% is co!"letel% conert into t#e inetic

ener*% o e!itte$ electron+ t#ereore t#e !ai!u! inetic ener*%

o t#e e!itte$ electron is *ien '%

f i mmm −=∆( )e( )i mmm +−=

( )4104."284.6"21.6" −×+−=u10"1.1 4−×=∆m

u284.6"*u21.6" ( )i == mm

( )( )( )282!4 1000.#1066.110"1.1 ×××= −−

%1026.2 14

ma+

−×= K

Q K =ma+

( ) 2cm∆=



PHYSICS CHAPTER 14

13

Ta'le 14.1 s#ows t#e alue o !asses or seeral nucli$es.

?iscuss w#et#er it is "ossi'le or to e!it s"ontaneousl% anal"#a "article.


I e!its an al"#a "article+ t#e α $eca% woul$ 'e re"resente$ '%

Since t#e total !ass ater t#e reaction is *reater t#an t#at 'eore t#ereaction+ t#ereore t#e reaction $oes not occur.

Ea!"le > :

Nucli$e /ass (u)

4.7729

22.33

29.315

He42

,l2!

1#

)a2#11

.able '!'.able '!'

,l2!1#

,l2!1#

,l2!1# )a2#

11→ + He42

+/!01'2 u+/!01'2 u ++!0101 u++!0101 u !33+/ u!33+/ u

+/!00+ u+/!00+ u



PHYSICS CHAPTER 14

14

is $eine$ as an induced nuclear reaction that does notan induced nuclear reaction that does not

occur spontaneously4 it is caused by a collision between aoccur spontaneously4 it is caused by a collision between a

nucleus and an energetic particles such as proton, neutron,nucleus and an energetic particles such as proton, neutron,

alpha particle or photonalpha particle or photon.

Consi$er a 'o!'ar$!ent reaction in w#ic# a tar*et nucleus (

is 'o!'ar$e$ '% a "article ++ resultin* in a $au*#ter nucleus -+an e!itte$ "article y an$ reaction ener*% Q:

so!eti!es t#is reaction is written in t#e !ore co!"act or!:

T#e calculation o reaction ener*% Q #as 'een $iscusse$ in

section 14.1.2.

'!'! Bombardment with energetic particles

Q++→+ -y+(

( )-y+( daughter nucleusdaughter nucleustarget (parenttarget (parentnucleusnucleus

bombardingbombarding

particleparticleemittedemitted

particleparticle



PHYSICS CHAPTER 14

15

Ea!"les o 'o!'ar$!ent reaction:

Q++→+ H/He ) 11

1!8

42

14! ( ) / p ) 1!

814! α

Q++→+ Hein42

!#

10

10"

,R

Q+→+ He2Hi 42

11

!# ( ) He pi 4

2!# α

( ) in !#

10" α

,R

,R

A nitro*en nucleus is conerte$ into an o%*en nucleusan$ a "roton i it is 'o!'ar$e$ '% an al"#a "article carr%in* certaina!ount o ener*%.

a. <rite $own an e"ression or t#is nuclear reaction+ s#owin* t#e

ato!ic nu!'er an$ t#e !ass nu!'er o eac# nucli$e an$

"article e!itte$.'. Calculate t#e !ini!u! ener*% o t#e al"#a "article or t#is

reaction to tae "lace.

(ien m p7.198>5× 17−29 *6 mα 7.99499 × 17−29 * 6 !ass o

nitro*en nucleus + m ) 2.>25>7× 17−29 *6 !ass o o%*en nucleus+

m/ 2.222× 17−29 * 6 c >.77× 17 ! s−1)

Ea!"le 4 :

)

14

! /

1!

8



PHYSICS CHAPTER 14

16


a. T#e e"ression re"resents t#e nuclear reaction is

'. T#e !ass $eect o t#e reaction is

T#ereore t#e !ini!u! ener*% o t#e al"#a "article or t#isreaction to tae "lace is

)14! /1!

8→ + Q+ H11+ He42

f i mmm −=∆( ) ( )H/He ) mmmm +−+=

$g101.2 #0−×−=∆m

( )26261066466.010#2"#0.2

−− ×+×=( )2626 1016!#".01082282.2 −− ×+×−

Q K =min ( ) 2

min cm K ∆=( )( )28#0 1000.#101.2 ××= −

%108.1 1#min −×= K



PHYSICS CHAPTER 14

17

Eercise 14.1 :ien c >.77× 17 ! s−1+ mn1.7798 u+ m"1.7782 u+

1. Co!"lete t#e ollowin* ra$ioactie $eca% e-uations :

a.

'.

c.

$.

e.

.

[ ] Hee 4

2

8

4 +→

[ ] ar Po 1#

"6

!

#8

240

4 ++→

( ) [ ] n#3 10

1#1"#

2#62 ++→

[ ] e )a 0

1

2

11 +→−

[ ] cc 4!

21

4!

21

+→∗

[ ] 5a 40

20

40

1 +→



PHYSICS CHAPTER 14

18

Eercise 14.1 :

2. Calculate t#e ener*% release$ in t#e al"#a $eca% 'elow:

(ien !ass o @2>+ m42>.75789 u 6 !ass o T#2>4+

m782>4.74>5> u an$ !ass o α "article + m

α4.77297> u)

ANS! :ANS! : /!15/!15× '3'3 '-'- 66>. T#e ollowin* nuclear reaction is o'taine$ :

?eter!ine t#e !ass o in ato!ic !ass unit (u).

(ien t#e !ass o nitro*en nucleus is 14.77>784 u)

ANS! :ANS! : '!33-15+ u'!33-15+ u

Q++→ He7 4

2

2#4

0

2#8

2

Me&"".0H5n ) 1

1

14

6

1

0

14

! ++→+

5146



PHYSICS CHAPTER 14

19

At the end of this chapter, students should be able to:At the end of this chapter, students should be able to:

7istinguish7istinguish the processes of nuclear fission andthe processes of nuclear fission and

fusion!fusion!

8plain8plain the occurrence of fission and fusion in the formthe occurrence of fission and fusion in the form

of graph of binding energy per nucleon!of graph of binding energy per nucleon!

8plain8plain chain reaction in nuclear fission of a nuclearchain reaction in nuclear fission of a nuclear

reactor!reactor!

7escribe7escribe the process of nuclear fusion in the sun!the process of nuclear fusion in the sun!

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14.2 Nuclear ission an$ usion (1 #our)



PHYSICS CHAPTER 14

20

'!+!' Nuclear fission is $eine$ as a nuclear reaction in which a heavy nucleusa nuclear reaction in which a heavy nucleus

splits into two lighter nuclei that are almost e#ual in masssplits into two lighter nuclei that are almost e#ual in mass

with the emission of neutrons and energywith the emission of neutrons and energy.

Nuclear fissionNuclear fission releases an a!ount o ener*% t#at is

greatergreater

thanthan t#e ener*% release$ in chemical reactionchemical reaction.

Ener*% is release$ 'ecause t#e average binding energy peraverage binding energy per

nucleon of the fission products is greater than that of thenucleon of the fission products is greater than that of the

parentparent.

It can 'e $ii$e$ into two t%"es: spontaneous fissionspontaneous fission er% rarel% occur.

induced fissioninduced fission 'o!'ar$in* a #ea% nucleus wit# slow

neutrons or t#er!al neutrons o low ener*% (a'out 17−2 e0).

T#is t%"e o ission is t#e i!"ortant "rocess in t#e ener*%

"ro$uction.

'!+ Nuclear fission and fusion



PHYSICS CHAPTER 14

21

n10∗2#6

2

a148"!

r 8"#"

2#"2

n10

n10

n10

Bor ea!"le+ consi$er t#e 'o!'ar$!ent o '% slowneutrons. ,ne o t#e "ossi'le reaction is

T#e reaction can also 'e re"resente$ '% t#e $ia*ra! in Bi*ure14.1.

,t#er "ossi'le reactions are:

2#"2

Q+++→→+ ∗ n#ar n 10148"!8"#"2#62102#"2

Nucleus in the ecited state!Nucleus in the ecited state!

Figure '!'Figure '!'

Q+++→→+ ∗

n#(er n10

1#"4

4#8

2#62

10

2#"2

Q+++→→+ ∗ n#ar n 10

144"6

8#6

2#62

10

2#"2



PHYSICS CHAPTER 14

22

/ost o t#e ission ra*!ents ($au*#ter nuclei) o t#e uraniu!2>5 #ae !ass nu!'ers ro! 03 to '3303 to '33 an$ ro! '-2 to '2'-2 to '2 ass#own in Bi*ure 14.2.

Figure '!+Figure '!+



PHYSICS CHAPTER 14

23

Calculate t#e ener*% release$ in /e0 w#en 27 * o uraniu!2>5

un$er*oes ission accor$in* to

(ien t#e !ass o @2>5 2>5.74>3> u+ !ass o neutron

1.7798 u+ !ass o r3 .31859 u+ !ass o Da144

14>.3228> u an$ N , 9.72× 172> !ol−1)


T#e !ass $eect ($ierence) o ission reaction or one nucleus @

2>5 is

Ea!"le 5 :

Q+++→+ n#ar n 10

144"6

8#6

10

2#"2

f i mmm −=∆( ) ( )nar n #mmmmm ++−+=

u186#.0=∆m

( ) −+= 0086!.104##.2#"

( )0086!.1#22!#.14#1!"6.88 ×++



PHYSICS CHAPTER 14

24


T#e ener*% release$ corres"on$s to t#e !ass $eect o one @2>5

is

2>5 × 17−> * o uraniu!2>5 contains o 9.72 × 172> nuclei

27 * o urainu!2>5 contains o

T#ereore

Ener*% release$

'% 27 * @2>5

( ) 2cmQ ∆=

Me&1!4=Q

( ) 22

u1

Me&'".#1u.186#0 c

c

=

nuclei1012." 2"×=

( )2#

#1002.6

102#"

20×

× −

( )( )1!41012." 2"×=

Me&101.8 2!×=



PHYSICS CHAPTER 14

25

A uraniu!2>5 nucleus un$er*oes ission reaction '% 'o!'ar$in* it

wit# a slow neutron. T#e reaction "ro$uces a strontiu!37 nucleus

+ a nucleus an$ t#ree ast neutrons.

a. <rite $own t#e e"ression re"resents t#e ission reaction.

'. I t#e ener*% release$ is 217 /e0+ calculate t#e ato!ic !ass onucleus .

(ien t#e !ass o @2>5 2>5.74>3> u+ !ass o neutron1.7798 u an$ !ass o Sr37 3.37885 u)


a. T#e e"ression re"resents t#e ission reaction is

Ea!"le 9 :

( )r 0#8

Q+++→+ n#(r n 10

14#"4

0#8

10

2#"2



PHYSICS CHAPTER 14

26


T#e ener*% release$ o 217 /e0 e-uialent to t#e !ass $eect or

@2>5 is

T#ereore t#e ato!ic !ass o t#e nucleus is *ien '%

( ) 2cmQ ∆=

u22"44.0=∆m

( ) 22

u1

Me&'".#1210 c

cm

∆=

f i mmm −=∆( ) ( )n(r n #mmmmmm ++−+=∆

u8#4.142( =m

( ) −+= 0086!.104##.2#"22"44.0( )0086!.1#0!!".8 ( ×++ m



PHYSICS CHAPTER 14

27

is $eine$ as a nuclear reaction that is self*a nuclear reaction that is self* sustaining as asustaining as aresult of the products of one fission reaction initiating aresult of the products of one fission reaction initiating a

subse#uent fissionsubse#uent fission reactionreaction. Bi*ure 14.> s#ows a sc#e!atic $ia*ra! o t#e c#ain reaction.

'!+!+ $hain reaction

Figure '!-Figure '!-Sti!ulation 14.1

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PHYSICS CHAPTER 14

28

Bro! Bi*ure 14.>+ one neutron initiall% causes one ission o a

uraniu!2>5 nucleus+ t#e two or t#ree neutrons release$ can *o

on to cause a$$itional issions+ so t#e "rocess !ulti"les. T#is reaction o'iousl% occurre$ in nuclear reactor.

$onditions to achieve chain reaction$onditions to achieve chain reaction in a nuclear reactor :

Slow neutronsSlow neutrons are 'etter at causin* ission so uraniu!

are !ie$ wit# a !aterial t#at $oes not a'sor' neutrons 'ut

slows t#e! $own. T#e issile !aterial !ust #as a critical si9ecritical si9e w#ic# is $eine$

as the minimum mass of fissile material that will sustainthe minimum mass of fissile material that will sustain

a nuclear chain reaction where the number of neutronsa nuclear chain reaction where the number of neutrons

produced in fission reactions should balance theproduced in fission reactions should balance the

number of neutron escape from the reactor corenumber of neutron escape from the reactor core. T#e uncontrolle$ c#ain reactions are use$ in nuclear wea"ons

ato!ic 'o!' (Bi*ure 14.4).

T#e controlle$ c#ain reactions tae "lace in nuclear reactors

(Bi*ure 14.5) an$ release ener*% at a stea$% rate.



PHYSICS CHAPTER 14

29

Figure '!Figure '! Figure '!2Figure '!2



PHYSICS CHAPTER 14

30

is $eine$ as a type of nuclear reaction in which two lighta type of nuclear reaction in which two light

nuclei fuse to form a heavier nucleus with the release ofnuclei fuse to form a heavier nucleus with the release of

large amounts of energylarge amounts of energy.

T#e ener*% release$ in t#is reaction is calle$ t#er!onuclear

ener*%.

Ea!"les o usion reaction releases t#e ener*% are

T#e two reactin* nuclei in usion reaction a'oe t#e!seles

#ae to 'e 'rou*#t into collision.

As 'ot# nuclei are "ositiel% c#ar*e$ t#ere is a stron*

re"ulsie orce 'etween t#e!+ w#ic# can onl% 'e oerco!e

i t#e reactin* nuclei #ae er% #i*# inetic ener*ies.

T#ese #i*# inetic ener*ies i!"l% te!"eratures o t#e or$er

o 17

.

'!+!- Nuclear fusion

Q++→+ nHeHH 10

#2

21

21

Q++→+ HHHH 11

#1

21

21



PHYSICS CHAPTER 14

31

At t#ese eleate$ te!"eratures+ #oweer usion reactionsare sel sustainin* an$ t#e reactants are in or! o a "las!a(i.e. nuclei an$ ree electron) wit# t#e nuclei "ossessin*

suicient ener*% to oerco!e electrostatic re"ulsion orces. T#e nuclear usion reaction can occur in usion 'o!' an$ in t#e

core o a star. ?euteriu!tritiu! usion is ot#er ea!"le o usion reaction

w#ere it can 'e re"resente$ '% t#e $ia*ra! in Bi*ure 14.9.

H21

?euteriu!

Busion

reaction

Tritiu!

H#1

Al"#a "article

He

4

2

Neutron

n10

Q++→+ nHeHH 10

42

#1

21

Sti!ulation 14.2

Figure '!/Figure '!/



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PHYSICS CHAPTER 14

32

A usion reaction is re"resente$ '% t#e e-uation 'elow:

Calculate

a. t#e ener*% in /e0 release$ ro! t#is usion reaction+

'. t#e ener*% release$ ro! usion o 1.7 * $euteriu!+(ien !ass o "roton 1.77825 u+ !ass o tritiu! >.719743 uan$ !ass o $euteriu! 2.714172 u)


a. T#e !ass $eect o t#e usion reaction or 2 $euteriu! nuclei is

Ea!"le 8 :

HHHH 11

#1

21

21 +→+

( ) ( ) p799 mmmm +−+=

u10##.4 #−×=∆m( ) ( )00!82".101604.#014102.2014102.2 +−+=

f i mmm −=∆



PHYSICS CHAPTER 14

33


a. T#ereore t#e ener*% release$ in /e0 is

'. T#e !ass o 2 $euteriu! nuclei is 4 × 17−> *.

4 × 17−> * o $euteriu! contains o 9.72 × 172> nuclei

1.7 * o $euteriu! contains o

T#ereore

Ener*% release$ ro!

1.7 * $euteriu!

( ) 2cmQ ∆=

Me&0#.4=Q

( ) 22

#

u1

Me&'".#1u10##.4 c

c

×= −

nuclei10"0".1 26×=

( )2#

#1002.6

104

0.1×

× −

( )( )0#.410"0".1 26×=

Me&100!.6 26×=



PHYSICS CHAPTER 14

34

T#e sun is a s!all star w#ic# *enerates ener*% on its own '%

!eans o nuclear usion in its interior.

T#e uel o usion reaction co!es ro! t#e "rotons aaila'le in

t#e sun.

T#e "rotons un$er*o a set o usion reactions+ "ro$ucin*

isoto"es o #%$ro*en an$ also isoto"es o #eliu!. Howeer+ t#e#eliu! nuclei t#e!seles un$er*o nuclear reactions w#ic#

"ro$uce "rotons a*ain. T#is !eans t#at t#e "rotons *o t#rou*#

a c%cle w#ic# is t#en re"eate$. Decause o t#is "roton"roton

c%cle+ nuclear usion in t#e sun can 'e sel sustainin*.

T#e set o usion reactions in t#e "roton"roton c%cle can 'eillustrate$ '% Bi*ure 14.8.

'!+! Nuclear fusion in the sun



PHYSICS CHAPTER 14

35

T#e a!ount o ener*% release$ "er c%cle is a'out 25 /e0. Nuclear usion occurs in t#e interior o t#e sun 'ecause t#e

te!"erature o t#e sun is er% #i*# (a""roi!atel% 1.5 × 178 ).

Qv +++→+ eHHH0

1

2

1

1

1

1

1

Q++→+ γ HeHH #2

11

21

Q+++→+ HHHeHeHe 11

11

42

#2

#2

neutrinoneutrinopositron (beta pluspositron (beta plus

Figure '!5Figure '!5



PHYSICS CHAPTER 14

36

Ta'le 14.2 s#ows t#e $ierences 'etween ission an$ usion

reaction.

T#e similaritysimilarity 'etween t#e ission an$ usion reactions is 'ot#

reactions produces energyproduces energy.

ra"# o 'in$in* ener*% "er nucleon a*ainst t#e !ass nu!'er

in Bi*ure 14. is use$ to e"lain t#e occurrence o ission an$

usion reactions.

'!+!2 $omparison between fission and fusion

.able '!+.able '!+

Fission Fusion

S"littin* a #ea% nucleus into twos!all nuclei.

Co!'ines two s!all nuclei to or!a lar*er nucleus.

It occurs at te!"erature can 'econtrolle$.

It occurs at er% #i*# te!"erature(17).

Easier to controlle$ an$sustaine$.

?iicult to controlle$ an$ asustaine$ controlle$ reaction #asnot %et 'een ac#iee$.

PHYSICS CHAPTER 14



PHYSICS CHAPTER 14

37

/ass nu!'er A

Din$in*

ener*

%"er

nucleo

n(/

e0&nucle

on)

reatest stabilityreatest stability

Figure '!1Figure '!1

FusionFusion

FissionFission

T#e rising partrising part o t#e 'in$in* ener*% cure

s#ows t#at ele!ents wit# low masslow mass

number can produce energy by fusionnumber can produce energy by fusion.

T#e falling partfalling part o t#e 'in$in* ener*% cures#ows t#at er% heavy elementsheavy elements suc# as

uraniu! can produce energy by fissionproduce energy by fission o

t#eir nuclei to nuclei of smaller mass number nuclei of smaller mass number .

PHYSICS CHAPTER 14



PHYSICS CHAPTER 14

38

Eercise 14.2 :ien c >.77× 17 ! s−1+ mn1.7798 u+ m"1.7782 u+

1. Co!"lete t#e ollowin* nuclear reaction e-uations:

a.

'.

c.

$.

e.

2. Calculate t#e ener*% release$ in Foule or t#e ollowin* usion

reaction:

(ien t#e !ass o $euteriu! >.>45× 17−28 *+ !ass o tritiu!5.77× 17−28 *+ !ass o He 9.948× 17−28 * an$ !ass oneutron 1.985× 17−28 *)

ANS! :ANS! : +!1+!1× '3'3 '+'+ 66

[ ] HeHe i 42

#2

6# +→+

[ ] H H )i 11

21

"828 +→+

[ ] n"(en 10

1#8"4

10

2#"2 ++→+

( ) 5 :::: e 126

4 α

( ) ) pn ::::: 16!

nHeHH 10

42

21

21 +→+

PHYSICS CHAPTER 14



39

PHYSICS CHAPTER 14

Next Chapter…CHAPTER 15 :

Ra$ioactiit%

matriculation physics nuclear reaction

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