KoRIA 와 이론핵물리학의전망 - 물질의기원을찾아서 - 천명기 ( 숭실대 ) 1
Contents 1. Nuclear Abundances 와 물질의기원 2. 별들의진화 3. 핵합성 (Nucleosynthesis) 4. KoRIA 와 ( 이론 ) 핵물리학 2
It is a remarkable fact that humans, on the basis of experiments and measurements carried out in the lab, are able to understand the universe in the early stages of its evolution, even during the first three minutes of its existence. Fowler (Nobel prize 1983) 3
1. 물질의기원과 Nuclear Abundances 4
p 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 eriod 6 7 1 H 3 Li 4 Be 11 12 Na Mg 19 K 37 Rb 55 Cs 87 Fr 20 Ca 38 Sr 56 Ba 88 Ra 21 Sc 39 Y 22 Ti 40 Zr * 72 Hf ** 104 Rf 23 V 41 Nb 73 Ta 105 Db 24 Cr 42 Mo 74 W 106 Sg 25 Mn 43 Tc 75 Re 107 Bh 26 Fe 44 Ru 76 Os 108 Hs 27 Co 45 Rh 77 Ir 109 Mt 28 Ni 46 Pd 78 Pt 110 Ds 29 Cu 47 Ag 79 Au 111 Rg 30 Zn 48 Cd 80 Hg 5 B 13 Al 31 Ga 49 In 81 Tl 112 113 Uub Uut 6 C 14 Si 32 Ge 50 Sn 82 Pb 114 Uuq 7 N 15 P 33 As 51 Sb 83 Bi 8 O 16 S 34 Se 52 Te 84 Po 9 F 17 Cl 35 Br 53 I 85 At 2 He 10 Ne 18 Ar 36 Kr 54 Xe 86 Rn 115 116 117 118 Uup Uuh Uus Uuo Periodic Table * Lanthanides 57 La 58 Ce 59 Pr 60 Nd 61 Pm 62 Sm 63 Eu 64 Gd 65 Tb 66 Dy 67 Ho 68 Er 69 Tm 70 Yb 71 Lu ** Actinides 89 Ac 90 Th 91 Pa 92 U 93 Np 94 Pu 95 Am 96 Cm 97 Bk 98 Cf 99 Es 100 Fm 101 Md 102 No 103 Lr Chemical series of the periodic table Alkali metals Alkaline earth metals Lanthanides Actinides Transition metals Poor metals Metalloids Nonmetals Halogens Noble gases 5
Diff = 10 7 Chondrites are stony meteorites that have not been modified 2009-08-14 due to melting or differentiation Summer School of Nuclear the parent body 6
Universality!! 7
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물질의기원은??? 9
Solar system Supernovae Model BIG-BANG STARS SUPERNOVAE? R-PROCESS R S(N=50) AGB STARS S-PROCESS COSMIC-RAYS R S(N=82) R S(N=126) ++ + Actinide 232 Th (14.05Gy) P 238 U (4.47 Gy) SPERNOVA-g PROCESS? 10
물질 ( 인간 ) 의기원은 밤하늘의별!!!! 2. 별의진화 11
Stellar Evolution 6~8 M_s <M < 25~30 M_s M> 25~30 M_s 12
우주의탄생이후 38 만년정도 ( 온도는 3000 K) 에서플라스마시대의종말로원자가형성되어원자끼리의중력에의한수축으로성간의가스구름이고밀도고온상태즉원시형태의별도탄생하게되면서온도는점점내려가게된다. 따라서이후의핵합성은중력에의한수축으로인하여온도가상승하는이러한별의내부에서나핵합성이가능해진다. 예를들어, 태양과같은주계열성에서는주로수소가연소해서헬륨이생기며, 적색거성에서는헬륨이연소하여탄소가생겨난다. 더욱더무거운원소역시별의진화와함께점차적으로형성되어, 이들이별의외각으로부터질량의방출또는초신성폭발등에의하여성간공간으로방출된다. 13
이와같이별의내부에서생겨난원소는일부가성간공간으로환원되어시간이지나감에따라우주전체에서무거운원소의비율이조금씩증가하게된다. 이러한별에서생성되는가장무거운원자핵은대부분철까지이다. 이후의중핵은주로초신성폭발에서생겨나는것으로생각되고있다 14
The onion-like layers of a massive, evolved star just prior to core collapse. (Not to scale.) Why Onion Structure?? 15
2. Helium Burning (3 alpha process and 16O production) 4 He + 4 He 8 Be 8 Be + 4 He 12 C + γ + 7.367 MeV Overview of the Triple-alpha process 16
>> Fe Overview of the CNO-I Cycle. 17
중력붕괴에의한수축과정은별의중심부를초고밀도로만들어전자들이양성자와결합하여많은수의중성자와중성미자를만들게된다. 이때중심의코아 (Fe 또는 Ni) 급격한중력수축을받게되어 bounce 되어 Shock Wave (Prompt Explosion) 를형성하게된다. 이들중성자는베타붕괴보다훨씬빠른속도 (rapid process) 로흡수되어안정선보다훨씬아래쪽의중성자과잉영역의원자핵을거쳐진행하게된다. 물론고에너지감마선도많이존재하여역방향으로광분해작용과평형상태를이루면서보다무거운원소로진행하게된다. 18
한편생성된중성미자는 trapping 을거쳐 core 부분에서강력한 bounce 되어강력한 shock wave 를형성하게되어 (Delayed Explosion) 초신성폭발을야기시킨다. 이때중성미자와불안정원자핵과의충돌은아직실험적으로확인되어있지않은영역이라고할수있다. 하지만최근의중성미자빔의사용이가능하게됨에따라많은실험이계획중이거나또는진행중이다. 그러나아직이론계산은미진하며많은노력이필요한시점이라고할수있다 19
Mechanism of Super Nova Explosion Within a massive, evolved star (a) the onion-layered shells of elements undergo fusion, forming an iron core (b) that reaches Chandrasekharmass and starts to collapse. The inner part of the core is compressed into neutrons (c), causing infalling material to bounce (d) and form an outward-propagating shock front (red). The shock starts to stall (e), but it is reinvigorated by neutrino interaction. The surrounding material is blasted away (f), leaving only a degenerate remnant. 20
Super Novae 21
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Pulsar Quasr 24
* 고온고밀도에서의상태방정식을 중심으로하는물리의이해 한편 RHIC 을중심으로하는 Mini Big Bang 의실험에서는 QGP 에관한연구가활발히진행중이다. 초신성에서는비록온도는 Big Bang 당시보다낮지만보통의핵물질이상의고밀도영역에서진행되는핵반응이라고할수있다. 이에따라고밀도의상태방정식을중심으로하는많은연구가진행중이다. 물론초신성폭발이후의중성자별의경우에는많은연구가진행중이지만... 25
3. Nucleosynthesis ( 핵합성 / 원소합성 ) When, Where and How??. Big Bang Nucleosynthesis. Star Revolution Nucleosynthesis. Supernovae Nucleosynthesis 26
Gamow s hypothesis (1946) 27
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Nucleosynthesis in Cosmos 293 2,771 3,064 NNDC (BNL, 2000) 2,10,18,36,54,86 :A.P. in Cou.Pot. 2,10,28,60,120 : in Har. Pot. 2,8,20,28,50,82,126 :N.P. in WS.Pot. s process 82 Stable Observed Unstable rp process 50 126 Stellar evolution 20 28 82 50 8 28 2009-08-14 Big Bang Summer School of Nuclear 8 r process Nuclear reactions in stars produce energy 29 generate the elements
Exotic (Unstable, Deformed ) Nuclei 30
S 과정 (Slow Process) 과 R 과정 (Rapid Process) Successive Neutron Capture 31
Rapid Proton Process 세번째는주로상대적으로무거운원자핵이면서, 중성자결핍영역 ( 또는 p-nuclei 영역 : 질량번호가 74 에서 196 까지이르는영역으로 s- 또는 r- process 로합성될수없는영역의원자핵으로양성자 drip line 근처에있으며일반적으로양성자가많은원자핵 ) 에서일어나는빠른양성자반응 (rp-process : rapid proton process) 이다. 이들영역에대한기본적인설명은폭발적인산소나네온연소동안에일어나는광분해반응 (Photo-disintegration) 만으로는충분한설명이되지못하고있다. 물론질량번호가비교적작은영역 ( 예를들어 Na, Al, Ti, Co) 에서도이러한 rp-process 가가능하다. 32
4. KoRIA 와핵물리학 ( 이론 ) 33
rp-process s-process r-process Network Calculation and Input Data Without understanding the exotic nuclei, Mission impossible is to trace the evolution of the universe in its hadron stage!! 34
Mass Fraction Mass Fraction 초신성에서의폭발적원소합성 주요원소질량비분포 16.2 M 超新星 : E =3 10 53 ergs, T =6 폭발직전 (Presupernova) 10 0 10-2 MeV 28 Si Inner 16 O 20 Ne 24 Mg 12 C O/C He/C He/N H 1 H 32 S 폭발후 (~1000 s) 10-4 10 0 1.6 1.8 2 2.2 2.4 56 Ni 28 Si 16 O 20 Ne 24 Mg 3 4 5 6 7 4 He 1 H 10-2 4 He 12 C 40 Ca 32 S 10-4 1.6 1.8 2 2.2 2.4 Mr / M 3 4 5 6 7 35
How to obtain the Input Data for the network calculation?? 36
1.809-MeV g-ray sky map, made by a 9-year survey of CGRO/COMPTEL Life time T1/2 = 0.7 x 10 6 yr << the age of Galaxy ~ billion yr Currently, very active nucleosynthesis occurring in our Galaxy What is the main contributor of 1.809-MeV g-rays in the sky? Massive stars in the phase of WR and Supernova II, or novae, or AGB? Reaction rate data related to the abundance of 26g Al is indispensible. 26 Al g. s. T1/2 = 0.7 x 10 6 yr b +, EC Carina 1 st state, 1.809 MeV Cygnus Region Inner Galaxy Vela Region 26 Mg g. s. 37
Reactions around 26 Al and their contributions 27 P 26 Si 25 Al 26 Al (p, g) b+ 24 Mg 25 Mg 26 Mg 38
25 Al, 26 Si beam production @ CRIB Primary beam: 24 Mg 8+, 7.434 MeV/u, ~500 ena Production target: 3 He gas (0.32 mg/cm 2 ), 3 He( 24 Mg, n) 26 Si * (p) 25 Al, 3 He( 24 Mg, n) 26 Si Secondary beam: 25 Al (3.4 MeV/u), 26 Si (3.95 MeV/u) 39
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How to describe the nuclear structure : The Nuclear Models Even the 3 body problem cannot be solved exactly!! Introduction of the Mean Field Potential!! 41
The N-N force in free space vs. an effective N-N interaction in the Mean Field Potential Remained (short range) Correlations Sources of many ambiguities in Nuclear Physics 42
Quasi Particle Concept Real World Cyber (Theoretical) World Hartree Fock Bogoliubob(HFB) Transformation Very Useful tool to understanding the exotic nuclei, which play vital roles in nucleo-synthesis 43
Hole states Hole states Particle states Fermi Energy Level 1 P(v) 0 1 P(v) 0 44
1. Hartree Fock Field (Mean Field Potential) 2. Deformed Bardeen Cooper Schriffer (DBCS) Theory 3. Hartree Fock Bogoliubob(HFB) Theory Particle-Hole Interaction (Long Range) Quasi Particle (ph,pp,hh interactions) and Deformations Pairing Correlations among different states Excited States 4. Deformed Quasiparticle RPA (DQRPA) 5. Beta Decay, Proton capture, Photo-disintegration. 6. Network Calculations for rp Nucleosynthesis 45
불안정원자핵의핵구조 (Nuclear Structure) 초신성핵합성과폭발 중성미자반응을포함한열핵반응 고온고밀도에서의핵물리학 46
또한최근의 RI (Radioactive Isotope) 빔의실험적이용이가능하게됨에따라종래의핵물리학이할수없었던불안정원자핵을중심으로하는핵물리영역이확대되고있다. 이에따라종래의약 100 여종의안정원자핵에제한되어있던핵물리학은약 6000-8000 개정도에이르는불안정원자핵이그대상에들어오게되고, 그들불안정원자핵이 우주의진화 에있어결정적인역할을하고있는것으로파악되어오늘날에는천체물리학으로까지그영역이확대되고있는상황이다. 이런상황은핵물리학의새로운 Renaissance 라고까지이야기되고있는실정이다. 47
천체핵물리학은별의탄생, 진화그리고종말에관련된핵반응을연구하여별의진화과정및원소의핵합성등을이해하고설명하고자하는것이다. 핵물리학이천체에서의핵합성과이를통한원소의기원을밝힌것은물리학의매우중요한업적가운데하나라고할수있다. 이러한핵반응에따른원소합성이론은 1957 년 Burbridge, Fowler, Hoyle 등과 Cameron 에의하여제시된후꾸준하게발전되어왔다. 그러나최근에는별의역사뿐만아니라우주의역사를이해하는데있어서도천체핵물리학은큰역할을하고있다. 48
KoRIA 물질의우주물리적기원 21 세기의첨성대 49
감사합니다.