Nuclear reactions The chain reaction

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Jared McKenzie
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1 Nuclar ractions Th chain raction

2 Nuclar ractions Th chain raction For powr applications want a slf-sustaind chain raction.

3 Natural U: 0.7% of 235 U and 99.3% of 238 U

4 Natural U: 0.7% of 235 U and 99.3% of 238 U Fission nutrons hav KE 2 MV; and 238 U can absorb ths highnrgy nutrons (not by fission) but 238 U dos not absorb slow nutrons.

5 Natural U: 0.7% of 235 U and 99.3% of 238 U Fission nutrons hav KE 2 MV; and 238 U can absorb ths highnrgy nutrons (not by fission) but 238 U dos not absorb slow nutrons. Want to slow nutrons to allow fission of 235 U and avoid absorption by 238 U.

6 Natural U: 0.7% of 235 U and 99.3% of 238 U Fission nutrons hav KE 2 MV; and 238 U can absorb ths highnrgy nutrons (not by fission) but 238 U dos not absorb slow nutrons. Want to slow nutrons to allow fission of 235 U and avoid absorption by 238 U. Also nd to nrich th uranium to svral prcnt of 235 U.

7 Natural U: 0.7% of 235 U and 99.3% of 238 U Fission nutrons hav KE 2 MV; and 238 U can absorb ths highnrgy nutrons (not by fission) but 238 U dos not absorb slow nutrons. Want to slow nutrons to allow fission of 235 U and avoid absorption by 238 U. Also nd to nrich th uranium to svral prcnt of 235 U. Finally want ach fission vn to produc nough nutrons to caus anothr fission vnt.

8 Natural U: 0.7% of 235 U and 99.3% of 238 U Fission nutrons hav KE 2 MV; and 238 U can absorb ths highnrgy nutrons (not by fission) but 238 U dos not absorb slow nutrons. Want to slow nutrons to allow fission of 235 U and avoid absorption by 238 U. Also nd to nrich th uranium to svral prcnt of 235 U. Finally want ach fission vn to produc nough nutrons to caus anothr fission vnt. Using modrator to slow down nutrons light nucli ar bst sinc a collision by a nutron will transfr mor kintic nrgy to th nuclus that is initially at rst.

9 Natural U: 0.7% of 235 U and 99.3% of 238 U Fission nutrons hav KE 2 MV; and 238 U can absorb ths highnrgy nutrons (not by fission) but 238 U dos not absorb slow nutrons. Want to slow nutrons to allow fission of 235 U and avoid absorption by 238 U. Also nd to nrich th uranium to svral prcnt of 235 U. Finally want ach fission vn to produc nough nutrons to caus anothr fission vnt. Using modrator to slow down nutrons light nucli ar bst sinc a collision by a nutron will transfr mor kintic nrgy to th nuclus that is initially at rst. Graphit (carbon) was usd by Frmi t al. in 1942.

10 Natural U: 0.7% of 235 U and 99.3% of 238 U Fission nutrons hav KE 2 MV; and 238 U can absorb ths highnrgy nutrons (not by fission) but 238 U dos not absorb slow nutrons. Want to slow nutrons to allow fission of 235 U and avoid absorption by 238 U. Also nd to nrich th uranium to svral prcnt of 235 U. Finally want ach fission vn to produc nough nutrons to caus anothr fission vnt. Using modrator to slow down nutrons light nucli ar bst sinc a collision by a nutron will transfr mor kintic nrgy to th nuclus that is initially at rst. Graphit (carbon) was usd by Frmi t al. in Most modrn ractors us havy watr D 2 O.

Natural U: 0.7% of 235 U and 99.3% of 238 U Fission nutrons hav KE 2 MV; and 238 U can absorb ths highnrgy nutrons (not by fission) but 238 U dos not absorb slow nutrons.

11 Natural U: 0.7% of 235 U and 99.3% of 238 U Fission nutrons hav KE 2 MV; and 238 U can absorb ths highnrgy nutrons (not by fission) but 238 U dos not absorb slow nutrons. Want to slow nutrons to allow fission of 235 U and avoid absorption by 238 U. Also nd to nrich th uranium to svral prcnt of 235 U. Finally want ach fission vn to produc nough nutrons to caus anothr fission vnt. Using modrator to slow down nutrons light nucli ar bst sinc a collision by a nutron will transfr mor kintic nrgy to th nuclus that is initially at rst. Graphit (carbon) was usd by Frmi t al. in Most prsnt-day ractors us havy watr D 2 O. (Cd)

12 Nuclar fusion (th sun s sourc of powr) Mostly fusion of protons in th cor of th sun

13 Nuclar fusion (th sun s sourc of powr) Mostly fusion of protons in th cor of th sun Dnsity of protons must b high nough to nsur a high rat of collision

14 Nuclar fusion (th sun s sourc of powr) Mostly fusion of protons in th cor of th sun Dnsity of protons must b high nough to nsur a high rat of collision and proton KE (T ~ 10 7 K) must b high nough so Coulomb rpulsion is ovrcom allowing strong attractiv nuclar forc to tak ovr.

15 Nuclar fusion (th sun s sourc of powr) Mostly fusion of protons in th cor of th sun Dnsity of protons must b high nough to nsur a high rat of collision and proton KE (T ~ 10 7 K) must b high nough so Coulomb rpulsion is ovrcom allowing strong attractiv nuclar forc to tak ovr. Th proton-proton cycl H 1H 1 H

16 Nuclar fusion (th sun s sourc of powr) Mostly fusion of protons in th cor of th sun Dnsity of protons must b high nough to nsur a high rat of collision and proton KE (T ~ 10 7 K) must b high nough so Coulomb rpulsion is ovrcom allowing strong attractiv nuclar forc to tak ovr. lctron nutrino Th proton-proton cycl H 1H 1 H

17 Nuclar fusion (th sun s sourc of powr) Mostly fusion of protons in th cor of th sun Dnsity of protons must b high nough to nsur a high rat of collision and proton KE (T ~ 10 7 K) must b high nough so Coulomb rpulsion is ovrcom allowing strong attractiv nuclar forc to tak ovr. lctron nutrino Th proton-proton cycl H 1H 1 H H H 3 2 H

18 Nuclar fusion (th sun s sourc of powr) Mostly fusion of protons in th cor of th sun Dnsity of protons must b high nough to nsur a high rat of collision and proton KE (T ~ 10 7 K) must b high nough so Coulomb rpulsion is ovrcom allowing strong attractiv nuclar forc to tak ovr. lctron nutrino Th proton-proton cycl H 1H 1 H H H H 4 2 H 2H 2H 2 ( 1 ) H 1

19 Nuclar fusion (th sun s sourc of powr) Mostly fusion of protons in th cor of th sun Dnsity of protons must b high nough to nsur a high rat of collision and proton KE (T ~ 10 7 K) must b high nough so Coulomb rpulsion is ovrcom allowing strong attractiv nuclar forc to tak ovr. lctron nutrino Th proton-proton cycl H 1H 1 H H H H 4 2 H 2H 2H 2 ( 1 ) H 1 two parts two parts on part

20 Nuclar fusion (th sun s sourc of powr) Mostly fusion of protons in th cor of th sun Dnsity of protons must b high nough to nsur a high rat of collision and proton KE (T ~ 10 7 K) must b high nough so Coulomb rpulsion is ovrcom allowing strong attractiv nuclar forc to tak ovr. lctron nutrino Th proton-proton cycl H 1H 1 H H H H 4 2 H 2H 2H 2 ( 1 ) H ( 1 ) 4 1H 2H two parts two parts on part

21 ( 1 ) 4 1H 2H Th two s will annihilat with two lctrons 2 γ

22 ( 1 ) 4 1H 2H Th two s will annihilat with two lctrons 2 γ So ovrall raction is ( 1 ) 4 H 2 H 2 ' s γ

23 ( 1 ) 4 1H 2H Th two s will annihilat with two lctrons 2 γ So ovrall raction is ( 1 ) 4 H 2 H 2 ' s γ (CAPA St #13 Prob. #6)

24 ( 1 ) 4 1H 2H Th two s will annihilat with two lctrons 2 γ So ovrall raction is ( 1 ) 4 H 2 H 2 ' s γ (CAPA St #13 Prob. #6) 2% of nrgy output carrid by nutrinos.

25 ( 1 ) 4 1H 2H Th two s will annihilat with two lctrons 2 γ So ovrall raction is ( 1 ) 4 H 2 H 2 ' s γ (CAPA St #13 Prob. #6) 2% of nrgy output carrid by nutrinos. Physicists & astronomrs intrstd in masuring nutrino output from sun.

26 ( 1 ) 4 1H 2H Th two s will annihilat with two lctrons 2 γ So ovrall raction is ( 1 ) 4 H 2 H 2 ' s γ (CAPA St #13 Prob. #6) 2% of nrgy output carrid by nutrinos. Physicists & astronomrs intrstd in masuring nutrino output from sun. Ovrall nrgy output = Q» 25 MV

27 Th binding nrgy curv E B

28 Th binding nrgy curv E B Fusing light nucli (low E B ) producs nucli with largr E B. Thus nrgy lft ovr.

29 Th binding nrgy curv Fission E B Fusing light nucli (low E B ) producs nucli with largr E B. Thus nrgy lft ovr.

30 Elmntary particls In 1960s thr was a vry larg numbr and varity of subatomic particls. Today only lctrons photons and a fw othr particls ar lmntary. Th rst such as protons and nutrons ar systms of smallr particls calld quarks. Th quark modl rducd th larg numbr of particls to a rasonabl valu and has succssfully prdictd nw quark combinations that hav bn subsquntly obsrvd.

31 Fundamntal forcs in natur Lt s look at th lctromagntic intraction using th photonmdiating-particl concpt.

32 E ph Fynman diagram t Violation of nrgy consrvation? No if t is short nough. h Invok uncrtainty principl E t 4π If t is short nough thn E ph < E no violation of E consrvation

33 Classification of particls (& antiparticls) Lptons: truly lmntary particls hav no structur or siz. Thy intract only through th wak & lctromagntic forcs. Thr ar six lptons:

34 Classification of particls (& antiparticls) Lptons: truly lmntary particls hav no structur or siz. Thy intract only through th wak & lctromagntic forcs. Thr ar six lptons: τ µ τ µ τ µ τ µ antiparticls particls

35 Classification of particls (& antiparticls) Lptons: truly lmntary particls hav no structur or siz. Thy intract only through th wak & lctromagntic forcs. Thr ar six lptons: τ µ τ µ τ µ τ µ antiparticls particls Hadrons: hav siz and structur. Thy intract primarily through th strong forc but lctromagntic forc is th nxt most important on. Two typs: baryons and msons

36 Classification of particls (& antiparticls) Lptons: truly lmntary particls hav no structur or siz. Thy intract only through th wak & lctromagntic forcs. Thr ar six lptons: τ µ τ µ τ µ τ µ antiparticls particls Hadrons: hav siz and structur. Thy intract primarily through th strong forc but lctromagntic forc is th nxt most important on. Two typs: baryons and msons π π π π n... p pn particls antiparticls

37 Classification of particls (& antiparticls) Lptons: truly lmntary particls hav no structur or siz. Thy intract only through th wak & lctromagntic forcs. Thr ar six lptons: τ µ τ µ τ µ τ µ antiparticls particls Hadrons: hav siz and structur. Thy intract primarily through th strong forc but lctromagntic forc is th nxt most important on. Two typs: baryons and msons π π π π n... p pn particls antiparticls

38 Consrvation laws: (mpirical) Which ractions ar allowd? charg baryon numbr (B) lpton numbr(l) & strangnss(s)

39 Consrvation laws: (mpirical) Which ractions ar allowd? charg baryon numbr (B) lpton numbr(l) & strangnss(s) γ p n π 0

40 Consrvation laws: (mpirical) Which ractions ar allowd? charg baryon numbr (B) lpton numbr(l) & strangnss(s) γ p n π 0 charg not consrvd

41 Consrvation laws: (mpirical) Which ractions ar allowd? charg baryon numbr (B) lpton numbr(l) & strangnss(s) γ p n π 0 charg not consrvd B = 1 B = 1 0 = 1

42 Consrvation laws: (mpirical) Which ractions ar allowd? charg baryon numbr (B) lpton numbr(l) & strangnss(s) γ p n π 0 charg not consrvd B = 1 L = 0 B = 1 0 = 1 L = 0

43 Consrvation laws: (mpirical) Which ractions ar allowd? charg baryon numbr (B) lpton numbr(l) & strangnss(s) γ p n π 0 charg not consrvd B = 1 L = 0 B = 1 0 = 1 L = 0 p p p p p p

44 Consrvation laws: (mpirical) Which ractions ar allowd? charg baryon numbr (B) lpton numbr(l) & strangnss(s) γ p n π 0 charg not consrvd B = 1 L = 0 B = 1 0 = 1 L = 0 p p p p p p charg consrvd

45 Consrvation laws: (mpirical) Which ractions ar allowd? charg baryon numbr (B) lpton numbr(l) & strangnss(s) γ p n π 0 charg not consrvd B = 1 L = 0 B = 1 0 = 1 L = 0 p p p p p p charg consrvd B = 1 1 = 2 B = = 2

46 Consrvation laws: (mpirical) Which ractions ar allowd? charg baryon numbr (B) lpton numbr(l) & strangnss(s) γ p n π 0 charg not consrvd B = 1 L = 0 B = 1 0 = 1 L = 0 p p p p p p charg consrvd B = 1 1 = 2 L = 0 B = = 2 L = 0

47 Must consrv all thr lpton numbrs: L L µ and L τ n p

48 Must consrv all thr lpton numbrs: L L µ and L τ n p charg consrvd

49 Must consrv all thr lpton numbrs: L L µ and L τ n p charg consrvd B = 1 B = 1

50 Must consrv all thr lpton numbrs: L L µ and L τ n p charg consrvd B = 1 L = 0 B = 1 L = 1 1 = 0

51 Must consrv all thr lpton numbrs: L L µ and L τ n p charg consrvd B = 1 L = 0 L µ = L τ = 0 B = 1 L = 1 1 = 0 L µ = L τ = 0

52 Must consrv all thr lpton numbrs: L L µ and L τ n p charg consrvd B = 1 L = 0 L µ = L τ = 0 B = 1 L = 1 1 = 0 L µ = L τ = 0 µ µ

53 Must consrv all thr lpton numbrs: L L µ and L τ n p charg consrvd B = 1 L = 0 L µ = L τ = 0 B = 1 L = 1 1 = 0 L µ = L τ = 0 µ µ charg consrvd

54 Must consrv all thr lpton numbrs: L L µ and L τ n p charg consrvd B = 1 L = 0 L µ = L τ = 0 B = 1 L = 1 1 = 0 L µ = L τ = 0 µ µ charg consrvd B = 0 B = 0

55 Must consrv all thr lpton numbrs: L L µ and L τ n p charg consrvd B = 1 L = 0 L µ = L τ = 0 B = 1 L = 1 1 = 0 L µ = L τ = 0 µ µ charg consrvd B = 0 B = 0 L = 0 L = 1 1 = 0

56 Must consrv all thr lpton numbrs: L L µ and L τ n p charg consrvd B = 1 L = 0 L µ = L τ = 0 B = 1 L = 1 1 = 0 L µ = L τ = 0 µ µ charg consrvd B = 0 B = 0 L = 0 L = 1 1 = 0 L µ = 1 L µ = 1

BETA DECAY VISUAL PHYSICS ONLINE

BETA DECAY VISUAL PHYSICS ONLINE VISUAL PHYSICS ONLINE BETA DECAY Suppos now that a nuclus xists which has ithr too many or too fw nutrons rlativ to th numbr of protons prsnt for stability. Stability can b achivd by th convrsion insid