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Opus in profectus

Nucleosynthesis

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big bang nucleosynthesis

By the first millisecond, the universe had cooled to a few trillion kelvins (1012 K) and quarks finally had the opportunity to bind together into free protons and neutrons. Free neutrons are unstable with a half-life of about ten minutes (614.8 s) and formed in much smaller numbers. The abundance ratio was about seven protons for every neutron. Before one neutron half-life passed nearly every neutron had paired up with a proton, and nearly every one of these pairs had paired up to form helium. By this time the universe had cooled to a few billion kelvins (109 K) and the rate of nucleosynthesis had slowed down significantly. By the time the universe was three minutes old the process had basically stopped and the relative abundances of the elements was fixed at ratios that didn't change for a very long time: 75% hydrogen, 25% helium, with trace amounts of deuterium (hydrogen-2), helium-3, and lithium-7. Big Bang nucleosynthesis produced no elements heavier than lithium. To do that you need stars, which means waiting around for at least 200 million years.

Big bang nuclear reactions

we are all made of stars

More than ninety per cent of the universe is composed of hydrogen and helium. Both elements have been around since shortly after the beginning of the universe. Yet, hydrogen and helium together won't make anything as complex and as interesting as the Earth, or a bacterium, or a refrigerator, or you and I. To do that we need carbon and oxygen and nitrogen and silicon and chlorine and every other naturally occurring element. Almost all the hydrogen and helium present in the universe today (and some of the lithium) were created in the first three minutes after the big bang. All of the other naturally occurring elements were created in stars.

Stars like the Sun

Proton-proton nuclear reactions

Details were discussed in the section on Fusion. The basic parts of the reaction are…

2[11H + 11H  →  21H + 0+1e (0.4 MeV) + 00ν (1.0 MeV)]
2[11H + 21H  →  32He + 00γ (5.5 MeV)]
32He + 32He  →  42He + 211H (12.9 MeV)

Which overall yields…

411H → 42He + 2[0+1e + 00γ + 00ν] (26.7 MeV)

Stars heavier than the Sun use 126C as a catalyst.

Carbon-nitrogen-oxygen nuclear reactions

You need really massive stars for this — say 20 to 120 times the mass of the Sun.

Really, really heavy stars do something different.

The Mass-5 and Mass-8 Bottlenecks. There are no stable isotopes (of any element) having atomic masses 5 or 8. But there is always a small amount of 84Be at any moment that is available to fuse with a third helium to produce 126C. This improbable sequence is called the triple-alpha process because the net effect is to combine 3 alpha particles to form a 126C nucleus. The triple-alpha process is not relevant in main sequence (normal) stars like the Sun because their core temperatures are too low. However, in the red giant phase, after many stars have accumulated vast amounts of helium in their core, the central temperature can rise high enough (108 K) to initiate the triple-alpha process.

42He +  42 He (92 keV)  →  84Be*
42He +  84Be*  (67 keV)  →  126C*
    126C*  →  126C + 00γ (7.4 MeV)

Overall

3[42He] → 126C + 00γ (7.4 MeV)

Triple alpha nuclear reactions

In order of increasing alpha number, the following forms of fusion take place…

Stable isotopes built from helium nuclei (alpha particles) * The most abundant form of solar argon 3618Ar is primordial — forged in the cores of the long dead ancestors of the Sun. The most abundant isotope of atmospheric argon 4018Ar is radiogenic — the decay product of radioactive potassium that escaped the Earth's crust.
alpha
number
mass
number
element(s) comments
1 4 He helium formed in all stars
2 8 no stable isotopes with this mass number
3 12 C carbon triple alpha process
4 16 O oxygen
5 20 Ne neon
6 24 Mg magnesium
7 28 Si silicon
8 32 S sulfur
9 36 Ar argon most abundant isotope of solar argon*
10 40 Ca calcium most abundant isotope of calcium
11 44 Ca calcium only 2.1% of all calcium atoms
12  48  Ti titanium
13 52 Cr chromium
14 56 Fe iron nuclear "ash"
Core nuclear reactions in massive stars
lifetime
remaining
core
temperature
core
reactions
107 years 107 K 411H → 42He  
106 years 108 K 342He →
126C + 42He →
126C
168O
 
103 years 1 × 109 K 168O + 42He →
2126C →
2010Ne
2412Mg
 
1  year 1.5 × 109 K 2010Ne + 42He → 2412Mg  
1 year 2 × 109 K 126C + 168O →
2168O →
2814Si
3216S
 
less than a week 4 × 109 K 2814Si + 42He →
3216S + 2810Mg →
3216S
5626Fe
 
less than a minute >1010 K explosive fusion,
neutron capture

How to Cook Everything

Mix it all up and get everything from hydrogen to uranium (and maybe even up to californium).

Mass defect per nucleon vs mass number

Elemental abundance graph, linear

Elemental abundance graph, logarithmic

Top 20 elements in the universe Source: WebElements
rank element per million kg per million atoms
1 H hydrogen 750,000 930,000
2 He helium 230,000 72,000
3 O oxygen 10,000 800
4 C carbon 5,000 500
5 Ne neon 1,300 80
6 Fe iron 1,100 20
7 N nitrogen 1,000 90
8 Si silicon 700 30
9 Mg magnesium 600 30
10 S sulfur 500 20
11 Ar argon 200 6
12 Ca calcium 70 2
13 Ni nickel 60 1
14 Al aluminum 50 2
15 Na sodium 20 1
16 Cr chromium 15 0.4
17 Mn manganese 8 0.2
18 P phosphorus 7 0.3
19 Co cobalt 3 0.06
20 K potassium 3 0.1
everything else 6 0.2

how like a god

Ernest Rutherford (1871–1937) New Zealand–Canada–England was the first to transform one element into another.

147N + 42He → 178O → 11H

technetium

promethium

transuranic, cisuranic, superheavy

First synthesis of artificial elements (some claims are disputed) Chicago: University of Chicago (Chicago, Illinois); GSI: Society for Heavy Ion Research (Darmstadt, Germany); JINR: Joint Institute for Nuclear Research (Dubna, Russia); LBL: Lawrence Berkeley National Laboratory (Berkeley, California); ORNL: Oak Ridge National Laboratory (Oak Ridge, Tennessee); RIKEN: Kokuritsu Kenkyū Kaihatsu Hōjin Rikagaku Kenkyūsho (Wako, Japan); Enewetak: Ivy Mike weapon test (Enewetak Atoll, Marshall Islands); Palermo: University of Palermo (Palermo, Italy)
    element year location process notes
043 Tc technet­ium 1937 Palermo 9642Mo + 21H → 9843Tc
061 Pm prometh­ium 1945 ORNL 14660Nd + 10n → 14761Pm + 0−1e
093 Np neptun­ium 1940 LBL 23892U + 10n → 23993Np + 0−1e
094 Pu pluton­ium 1941 LBL 23892U + 21H → 23894Pu + 210n + 0−1e
095 Am americ­ium 1944 Chicago 23994Pu + 210n → 24195Am + 0−1e + 200γ
096 Cm cur­ium 1944 Chicago 23994Pu + 42He → 24296Cm + 10n
097 Bk berkel­ium 1949 LBL 24195Am + 42He → 24597Bk
098 Cf californ­ium 1950 LBL 24296Cm + 42He → 24698Cf
099 Es einstein­ium 1952 Enewetak found in radioactive fallout
100 Fm ferm­ium 1952 Enewetak found in radioactive fallout
101 Md mendelev­ium 1955 LBL 25399Es + 42He → 254101Md + 10n
102 No nobel­ium 1965 JNR 24395Am + 157N → 254102No + 410n
103 Lw lawrenc­ium 1961 LBL 250–25298Cf + 10–115B → 258–259103Lw + 3–510n
104 Rf rutherford­ium 1964 JINR 24294Pu + 2210Ne → 260104Rf + 410n
105 Db dubnium
dubnium
1970 JINR
LBL
24395Am + 2210Ne → 260105Db + 410n
24998Cf + 157N → 260105Db + 410n
106 Sg seaborg­ium 1974 LBL 24998Cf + 188O → 263106Sg + 410n
107 Bh bohr­ium 1981 JINR 20483Bi + 5424Cr → 258107Bh
108 Hs hass­ium 1984 GSI 20882Pb + 5826Fe → 266108Hs
109 Mt meitner­ium 1982 GSI 20983Bi + 5826Fe → 266109Mt + 10n
110 Ds darmstadt­ium 1994 GSI 20882Pb + 6228Ni → 269110Ds + 10n
111 Rg roentgen­ium 1994 GSI 20983Bi + 6428Ni → 272111Rg + 10n
112 Cp copernic­ium 1996 GSI 20882Pb + 7030Zn → 278112Cp
113 Nh nihon­ium 2004 RIKEN 20983Bi + 7030Zn → 278113Nh + 10n
114 Fl flerov­ium 1999 JINR 24494Pu + 4820Ca → 289114Fl + 310n
115 Mc moscov­ium 2003 JINR 24395Am + 4820Ca → 288115Mc + 310n
116 Lv livermor­ium 2000 JINR 24896Cm + 4820Ca → 292116Lv + 410n
117 Ts tenness­ine 2010 JINR 24997Bk + 4820Ca → 293117Ts + 410n  
118 Og oganess­on 2002 JINR 24998Cf + 4820Ca → 294118Og + 310n
119 Uue ununenn­ium not yet synthesized  
120 Ubn unbinil­ium not yet synthesized  
121 Ubu unbiun­ium not yet synthesized  
122 Ubb unbib­ium not yet synthesized