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Feb 08, 2023 30 likes •383 views

The Explosive Lives of Stars: Producing Elements in the Cauldrons of the Cosmos Catherine M. Deibel Department of Physics & Astronomy Louisiana State University Conference for Women in Undergraduate Physics 01/18/14 1 13.7 Billion

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01/18/14 Conference for Women in Undergraduate Physics

The Explosive Lives of Stars:

Producing Elements in the Cauldrons of the Cosmos

Catherine M. Deibel Department of Physics & Astronomy Louisiana State University

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13.7 Billion (13,700,000,000) years ago the universe began with

THE BIG BANG

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The first atoms

  • A fraction (1/10,000,000,000,000,000,000,000,000,000,000)
  • f a second after the BIG BANG electrons are created

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The first atoms

  • One millionth of a second (.000001 seconds) after the

BIG BANG protons and neutrons are formed

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The first atoms

  • 3 minutes after the BIG BANG the first atoms form

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After the Big Bang

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Aluminum (Al) Gold (Au) Calcium (Ca) Sodium (Na) Oxygen (O) in water (H2O)

What about everything else?

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Where does the rest of the Periodic Table come from?

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  • Adding or subtracting neutrons makes different isotopes
  • A hydrogen nucleus is one proton

– Adding one neutron to hydrogen makes the isotope deuterium – Then adding one proton makes the isotope 3He – Then adding one neutron makes the isotope 4He

  • Total number of protons (“atomic number”) = Z
  • Total number of neutrons = N
  • N + Z = A, “atomic mass number” or number of nucleons

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Beyond the Periodic Table . . .

1H

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  • Adding or subtracting neutrons makes different isotopes
  • A hydrogen nucleus is one proton

– Adding one neutron to hydrogen makes the isotope deuterium – Then adding one proton makes the isotope 3He – Then adding one neutron makes the isotope 4He

  • Total number of protons (“atomic number”) = Z
  • Total number of neutrons = N
  • N + Z = A, “atomic mass number” or number of nucleons

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H

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Beyond the Periodic Table . . .

1H

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  • Adding or subtracting neutrons makes different isotopes
  • A hydrogen nucleus is one proton

– Adding one neutron to hydrogen makes the isotope deuterium – Then adding one proton makes the isotope 3He – Then adding one neutron makes the isotope 4He

  • Total number of protons (“atomic number”) = Z
  • Total number of neutrons = N
  • N + Z = A, “atomic mass number” or number of nucleons

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H

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He

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Beyond the Periodic Table . . .

1H

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  • Adding or subtracting neutrons makes different isotopes
  • A hydrogen nucleus is one proton

– Adding one neutron to hydrogen makes the isotope deuterium – Then adding one proton makes the isotope 3He – Then adding one neutron makes the isotope 4He

  • Total number of protons (“atomic number”) = Z
  • Total number of neutrons = N
  • N + Z = A, “atomic mass number” or number of nucleons

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H

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He

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Beyond the Periodic Table . . .

1H

He

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protons + neutrons

AX or Z AX

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  • Keep adding protons and neutrons to make

thousands of isotopes

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Beyond the Periodic Table . . .

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Where does the rest of the Periodic Table come from?

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Where does the rest of the Periodic Table come from?

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Different Nuclei are produced in different stars

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!" D.K. Galloway et al., ApJ 601 466 (2004).

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Neutron Stars

  • Neutron stars are extremely compact,

dense objects (! ~ 1014 g/cm2)

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Neutron Stars

  • Neutron stars are extremely compact,

dense objects (! ~ 1014 g/cm2)

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!# D.K. Galloway et al., ApJ 601 466 (2004).

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X-Ray Burst Nucleosynthesis

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Z N Z-1 N Z-1 N+1 Z N+1 Z+1 N+1 Z+2 N+1 Z+1 N Z+2 N Z N+2 Z+1 N+2 Z+2 N+2 Proton decay: (γ,p) Alpha capture: Proton capture: (p,γ) Beta decay: (β+) (α,p) (α,γ)

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X-Ray Burst Nucleosynthesis

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www.jinaweb.org

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How do nuclei react?

  • $%&'()*(a reaction rate?

(i.e. What is the probability of two nuclei reacting in the stellar plasma?)

  • Thermal distribution of nuclei in

stellar plasma: Maxwell-Boltzmann distribution

  • The probability of the interaction

between two nuclei: nuclear cross section

  • Temperature dependent - difgerent

temperatures in stars probe difgerent energies in nucleus

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Reaction Rates

  • !"#$%&'()*+(!"#$%&&'()&*+,"--./01*20345)-(%&(,%)*()*+(
  • 46&%"2.62)11.1%65)-..'%-+.()*+(2%"65)-.2"*%
  • !"/(/+."&0&)(/+012"&(/0)+.3
  • ! exp(-E)
  • ! nuclear spin, J
  • ! nuclear widths, "
  • 4,"(,05.()"(.)6$5(/+012"&.(/0)+.(0&$(1/"..(.+12"&.3
  • 7%/+1)#58(9+0.6/%&'()*+(/+012"&(/0)+(%).+#:
  • ;&$%/+1)#58($+)+/9%&%&'($%<+/+&)(1"9="&+&).(":()*+(

/+012"&(/0)+

  • +>'>("+?(@!A=B""C#

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30S 34Ar 33Cl

α p0,1,2

g.s. g.s. g.s. Ex, J

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  • Using accelerators with different types of detectors we can

measure what nuclear reactions happen in stars

  • A particle beam is accelerated and impinges on a target
  • Outgoing particles are detected

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Studying Nuclear Reactions in the Laboratory

DETECTOR beam " target

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Studying Nuclear Reactions in the Laboratory

  • Charged particles can be manipulated

by magnetic fields and separated by

– charge – mass – energy

  • Detected using

– ionization chambers – silicon detectors – CsI detectors – gamma detectors

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Prototype Si array Si array Recoil Detector Target fan Beam

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HELIcal Orbit Spectrometer

  • Beam of radioactive nuclei directed

through center of solenoid

  • Impinges on a target of light nuclei (e.g.

hydrogen, helium, etc.)

  • Reaction products measured by detectors
  • Reaction products tell us:

– excitation energy levels – spins of levels – reaction rate information

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Excited States in 18O (MeV)

States in 18O from

14O(6Li,d)18O

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33Cl(p,!)30S

Measurement

25 Rotatable arm

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(!,p)-process waiting points:

30S(!,p)33Cl Measurement

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  • c. m. Energy (MeV)

Cross Section (mb) (!0,p) NON-SMOKER converted (!0,p0) data (b)

  • (!,p) reactions on waiting points

(22Mg, 26Si, 30S, and 34Ar) may have significant effects on type I X-ray bursts

– final elemental abundances – energy generation – double-peaked luminosity profiles

  • Measured cross sections

(probability of reacting) larger than theoretical predictions:

– reaction rate is bigger!

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C.M. Deibel ett al, submitted (2011).

30S(!0,p)33Cl

J.L. Fisker et al.,ApJ 608, L61 (2004).

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Experiments for X-ray bursts

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Up to 1300 cm2 of 1-mm-thick Si backed with 2-cm-thick CsI Annular array for forward/ backward angles Annular gas proportional counter surrounds beam axis Active target+detector Up to 3 rings of 12 modules in barrel formation

ANASEN IC

Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN)

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  • Supernova models don’t explode
  • We don’t know where all the heavy

elements are made

  • Most reactions that happen in stars

have not been studied

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Embarrassing truths about NA

a.k.a. why we stay employed

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Cowan & Sneden, Nature 440 (2006) 1151.

Z>55 pattern matches solar

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  • Supernova models don’t explode
  • We don’t know where all the heavy

elements are made

  • Most reactions that happen in stars

have not been studied

  • But the future is bright . . .

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Embarrassing truths about NA

a.k.a. why we stay employed

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  • Supernova models don’t explode
  • We don’t know where all the heavy

elements are made

  • Most reactions that happen in stars

have not been studied

  • But the future is bright . . .

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Embarrassing truths about NA

a.k.a. why we stay employed

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Thanks!

Blackmon Rascoe Zganjar Lai Williams Macon Lauer Afanasieva Linhardt

Gardiner