LLNL-PRES-648640 This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC
Collaborator: P. Navrátil (TRIUMF)
CUWiP’14
Sofia Quaglioni
From nucleons, to nuclei, to fusion reactions
Berkeley, January 19, 2014
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Outline
§ The job of a theoretical nuclear physicist • Can we accurately describe how nuclei are put together from the
neutron and proton constituents?
• Can we predict the phenomena of nuclear reactions based on colliding nuclei made of interacting nucleons?
§ About myself • Formation, career, life
§ Questions?
Betelgeuse
α Alpha particle
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One of the central goals of nuclear physics is to come to a basic understanding of the structure and dynamics of nuclei
Can we accurately predict reactions in Earth-based fusion facilities?
Can we understand exotic nuclei?
What is the nature of the nuclear force?
What are the nuclear reactions that drive stars?
What is the origin of the elements?
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From nucleons to nuclei and their reactions
Based on the laws of Quantum Mechanics, can we describe nuclei and reactions between nuclei in terms of interacting nuclei?
§ Two major obstacles:
1. Interactions among nucleons are not known precisely
- Need to test different models
2. Many-body problem extremely hard to solve:
- << … many Hottentot tribes do not have in their vocabulary the names for numbers larger than three. Ask a native down there how many sons he has or how many enemies he has slain, and if the number is more than three he will answer “many” … >>
From: “One two three … infinity” by G. Gamow
proton neutron
A nucleons
quark
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The nuclear many-body problem § Solve the equations of Quantum Mechanics
• A (all active) nucleons – 9 × A degrees of freedom (position, spin, isospin)
• Nucleons cannot occupy the same quantum state (Pauli principle)
• Nucleons can interact in pairs, but also in triplets
• Exact/analytical calculations impractical! Need High Performance Computers
§ My job: develop “smart” theoretical approaches and efficient parallel computer codes to solve this problem
• If my theory is right it will reproduce known measured quantities and can be used to make predictions
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I will show cross sections, usually indicated by “σ” § A “classical” view:
§ “Microscopically” things are much more fuzzy … • The “effective area” depends on
- Type of interaction, energy, etc. …
σ Projectile/probe: e.g., tennis balls
Target: e.g., steel disk
Detector: e.g., Velcro
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Scattering and cross section (effective area)
§ Rutherford scattering is the most famous example (1909)
€
P =NT σ1 cm2 =
Ns
NI
H. Geiger E. Rutherford
E. Marsden
€
dσdΩ
=14Ze2
E$
% &
'
( )
21
sin4 (ϑ /2)
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3H(d,n)4He astrophysical S-factor!
Nuclear astrophysics: Predictions of Big Bang nucleosystesis for light-nucleus abundances Fusion research and Plasma physics: d+T is the easiest fusion to achieve on Earth; 3H(d,γ)5He branch useful for diagnostic, not known well enough
Atomic physics: Considerable electron-screening effects in d+3He not completely understood
The 3H(d,n)4He and 3He(d,p)4He fusion P. Navrátil, S. Quaglioni, Phys. Rev. Lett. 108, 042503 (2012)
3H
d
4He
n
7Li
3He
D 4He
Astrophysical S-factors!
10 100 1000Ekin [keV]
0
5
10
15
20
S-fa
ctor
[MeV
b]
Bo52Kr87Sch89Ge99Al01Al01Co050d*+0d'*1d*+1d'*3d*+3d'*5d*+5d'*7d*+5d'*9d*+5d'*
d+3He → p+4He
(b)
10 100 1000Ekin [MeV]
0
5
10
15
20
25
30
35
S-fa
ctor
[MeV
b]
BR51AR52CO52AR54He55GA56BA57GO61KO66MC73MA75JA84BR879d*+ 5d'*
3H(d,n)4He
My theory
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The elastic n-3H cross section for 14 MeV neutrons, important for understanding how the fuel is assembled in an implosion at NIF, was not known precisely enough
§ Nuclear theory was asked to help § Calculation corrected at forward
angles to account for target breakup (~ 15% effect)
Delivered evaluated data with required 5% uncertainty
Accurate evaluations and uncertainties for fusion diagnostic
Ab initio theory reduces uncertainty due to conflicting data (�,w,, ,)
3H(n,n)3H cross section!
My theory
corrected
n (14 MeV) 3H
d
4He
3H
3H
n
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Working hard or having fun?
§ The physics of atomic nuclei is fundamental to the very existence of the universe.
§ Being a nuclear theorist and helping to complete the puzzle can be a lot of fun!
§ And now about myself …
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About myself
1. Born in Italy (1978)
2. Liceo Classico studies (1991 - 1996)
3. Laurea (B.S.+M.S.) in physics (1996 – 2001)
• Who changed my mind?
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Prof. Giuseppina Orlandini, my inspiration and mentor
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About myself
4. Ph.D. in Theoretical Nuclear Physics (2001-2005)
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… all the while studying to become an opera singer
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About myself
5. Postdoc at the University of Arizona (2005 - 2006)
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I met my future husband … physicist too
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About myself
6. Postdoc at LLNL (2005 - 2009)
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A lot happened in 2009
2009 Outstanding Postdoc Fellow
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About myself
7. LLNL Member of Scientific Staff (2009 - present)
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2010 and 2013: two very productive years
2010, Leon Yves
2013, Filippo Pietro
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2011 DOE’s Early Career Award
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Summarizing
Questions?
§ I succeeded to get a higher education in physics § I was able to combine my passion for physics and music
§ I did not give up my aspirations of being a wife and a mom
§ My children did not slow down but gave a boost to my career
§ I have a very full life, but I love it.
If you really want it, nothing can stop you!
