Nuclear Theory at TRIUMF

Canada’s national laboratory for particle and nuclear physics Laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules

Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Propriété d’un consortium d’universités canadiennes, géré en co-entreprise à partir d’une contribution administrée par le Conseil national de recherches Canada

Nuclear Theory at TRIUMF

Sonia Bacca | Research Scientist | TRIUMF Adj. Prof. | University of Manitoba

For the TRIUMF Theory Group

Nuclear Halo

Theory Cluster

Wednesday, 13 November, 13

Nov 14 2013 Nuclear Theory at TRIUMF 2

Theory Group OverviewMake progress in our understanding of the building blocks of matter and provide theoretical guidance to interpret experiments done at TRIUMF and elsewhere

• What is the mechanism of electro-weak symmetry breaking?

• How does the strong force form stable and unstable nuclei?

• What is the role of particles and nuclei in astrophysics?

Mission:

The TRIUMF Theory Group has diversified and broad interests in subatomic physics, encompassing particle and nuclear physics. Our goal is to tackle big questions like



Theory Group OverviewMake progress in our understanding of the building blocks of matter and provide theoretical guidance to interpret experiments done at TRIUMF and elsewhere

• What is the mechanism of electro-weak symmetry breaking?

• How does the strong force form stable and unstable nuclei?

• What is the role of particles and nuclei in astrophysics?

Mission:

The TRIUMF Theory Group has diversified and broad interests in subatomic physics, encompassing particle and nuclear physics. Our goal is to tackle big questions like

People: 5 Staff Scientists [NRC funded, R.Woloshyn retiring ongoing search for replacement]

7 Research Associates [5 NRC funded and 2 NSERC funded]

4 Graduate Students [UBC, SFU, U of Manitoba, NSERC funded]

2 Undergraduate Students [UBC and SFU; NRC and NSERC funded]



Scientific Excellence


Nov 14 2013 Nuclear Theory at TRIUMF

• Organization of workshops 18 local workshops in the last 5 yearsIn 2013:- Progress in ab-initio techniques in nuclear physics, Feb 21-23- Neutrinos and nuclear theory, April 29 - May 3- Cosmology at colliders, Dec 9-11Participated in organizing international workshops at Aspen Centre of Physics, Institute of Nuclear Theory and European Centre of Theoretical Studies

4

Recent Activities




4

Recent Activities

• Numerous invited plenary talks at major conferencesincluding International Nuclear Physics Conference, Few-Body Conference, Higgs ModelsInvited colloquiums at university departments -15 in the last 3 years-




4

Recent Activities

• Successful HQP We have placed our people into prestigious postdocs and faculty positions S.Bacca, RA Research Scientist@TRIUMFJ. Braun, RA Assistant professor@TU DarmstadtK.Hebeler, RA Herzberg Fellow, GermanyR.Sharma, RA Assistant professor@TIFR, India P.Winslow, Ph.D. Student Postdoc@U Mass Amherst

• Numerous invited plenary talks at major conferencesincluding International Nuclear Physics Conference, Few-Body Conference, Higgs ModelsInvited colloquiums at university departments -15 in the last 3 years-



• Unique training/research experience for Canadian and international students attract students from Canadian universities and abroad

5

Recent Activities




5

Recent Activities

• Numerous active collaborations within Canada and abroad - 41 external collaborators -




5

Recent Activities

• Act as a centre for visitors and collaborators - 50 in 2013 -





5

Recent Activities



• Growing publication record

2008 2009 2010 2011 2012 20130

10

20

30

40Theory Publications

/YTD




5

Recent Activities



6 Phys. Rev. Lett. in 2013

• Growing publication record

2008 2009 2010 2011 2012 20130

10

20

30

40Theory Publications

/YTD


Nuclear Theory

6N

Z


Nuclear Theory

6

The ultimate goal is to develop a unified theory of all nuclei in the nuclear chart

N

Z


Nuclear Theory

6


ab-initio

N

Z


Nuclear Theory

6


Nucleus Proton

QCDSystem of strongly interacting

protons and neutrons

ab-initio

N

Z


Nuclear Theory

6


Nucleus Proton



Chiral Effective Field Theory [ EFT] Theoretical tool to systematically derive forces among nucleons preserving the symmetries of QCD where two- and three-nucleon forces arise naturally

�

ab-initio

N

Z


Nuclear Theory

6


Nucleus Proton




�

ab-initio

N

Z

two-nucleon forcesNN


Nuclear Theory

6


Nucleus Proton




�

ab-initio

N

Z



Nuclear Theory

6


Nucleus Proton




�

+ three-nucleon forces3N

ab-initio

N

Z



Nuclear AstrophysicsAstrophysics requires input from nuclear theory to answer questions like:

• What is the nature of neutron stars? Need for NN, 3N, ... for the EOS

7

Supernovae Explosion

Neutron star Neutron star merger

Heavy elements in r-process Need for masses, half lives, single particle structure

• How did the nucleosynthesis of elements occur? Light elements in BBN Need for fusion cross sections

more in Dillmann’s and Ruiz’s talks



Synergy between theory and experiment



Pohl et al., Nature (2010)µH Lamb shift

ordinary Hydrogen

e-

µ-

µ-

Strong experimental program at PSI (Switzerland) to unravel this mystery by studying other µ-atoms?

The Proton Radius Puzzle

Big questions of this decay: is lepton universality valid?

How small is the proton?

�E2S�2P = �QED + �nucl +m3

r(Z↵)4

12hR2i

related to the excitation ofthe nucleus

need to know it at 5% level



Pohl et al., Nature (2010)µH Lamb shift

ordinary Hydrogen

e-

µ-

µ-

Strong experimental program at PSI (Switzerland) to unravel this mystery by studying other µ-atoms?

The Proton Radius Puzzle

Big questions of this decay: is lepton universality valid?

How small is the proton?

�E2S�2P = �QED + �nucl +m3

r(Z↵)4

12hR2i

related to the excitation ofthe nucleus

need to know it at 5% level

From experiment

Nuclear structure corrections in µ4He+

Dipole Excitation in 4He

Theory

C.Ji et al., PRL 111, 143402 (2013)

�nucl = �3.1± 20% meV

�nucl = �2.47± 6% meVFrom Theory

from EFT�



two proton halo

one proton halo

one neutron halo

two neutron halo

four neutron halo

• Exotic nuclei with an interesting structure

Halo n/p6He 28He 311Li 2.6612C 1

• Neutron halos: Large n/p ratio (neutron-rich)

208Pb12 fm11Li 7 fm

Halo Nuclei



• High-precision Penning trap and laser spectroscopy techniques allow accurate measurements of energies and charge radii of exotic isotopes

Helium chain

and Borromean halo nucleus

4He3He 5He 7He6He 8He

....

bound unboundand halo

bound bound boundunbound

Halo Nuclei

Nuclear Theory at TRIUMFWednesday, 13 November, 13



Helium chain



....



Halo Nuclei

0 0.2 0.4 0.6 0.8 1 1.2 1.4S2n [MeV]

1.7

1.8

1.9

2

2.1

r pp [f

m]

GFMCNCSMFMDMCMEIHH

6He

Vlow k(N3LO)

EXP

⇤

⇒ better constraint on radius as well

Calculations from Hyper-spherical Harmonics (S.B)

Brodeur et al., PRL 108, 052504 (2012)

S2n from TITAN masses/energies

NN from EFT

+3N

�

S2n = BE(6He)�BE(4He)

@TRIUMF

6He




Helium chain



....



Pointing towards the importance

of three-nucleon forces

Halo Nuclei

0 0.2 0.4 0.6 0.8 1 1.2 1.4S2n [MeV]

1.7

1.8

1.9

2

2.1

r pp [f

m]

GFMCNCSMFMDMCMEIHH

6He

Vlow k(N3LO)

EXP

⇤



Brodeur et al., PRL 108, 052504 (2012)


NN from EFT

+3N

�


@TRIUMF

6He




Helium chain



....





Halo Nuclei

Are heavier isotopes bound?7He resonanceBaroni et al., PRL 110, 022505 (2013)PRC 87, 034326 (2013)

0 0.2 0.4 0.6 0.8 1 1.2 1.4S2n [MeV]

1.7

1.8

1.9

2

2.1

r pp [f

m]

GFMCNCSMFMDMCMEIHH

6He

Vlow k(N3LO)

EXP

⇤



Brodeur et al., PRL 108, 052504 (2012)


NN from EFT

+3N

�


@TRIUMF

6He




Helium chain



....





Halo Nuclei

Are heavier isotopes bound?7He resonanceBaroni et al., PRL 110, 022505 (2013)PRC 87, 034326 (2013)

0 0.2 0.4 0.6 0.8 1 1.2 1.4S2n [MeV]

1.7

1.8

1.9

2

2.1

r pp [f

m]

GFMCNCSMFMDMCMEIHH

6He

Vlow k(N3LO)

EXP

⇤



Brodeur et al., PRL 108, 052504 (2012)


NN from EFT

+3N

�


@TRIUMF

6He

more on 6He in poster by Romero-Redondo



Reactions for Astrophysics


The predicted solar neutrino flux from the 8B decay is proportional to the thermal average rate of the 7Be(p, �)8B radiative capture reaction

Solar neutrinos measured by SNO and Super-Kamiokande

Nuclear Theory at TRIUMF 12







0 0.5 1 1.5 2 2.5Ekin [MeV]

0

5

10

15

20

25

30

35

40

S 17 [e

V b

]FilipponeStriederHammacheHassBabyJunghansSchuemannDavidsKikuchiDe04 MN E1NCSM/RGM E1

7Be(p,γ)8B

(a)

@TRIUMF

ab-initiophenomenology

NN from EFT�

Solar conditions cannot be reproduced in the Lab

Reaction cross sections are measured at higher energy than needed

Need a reliable ab-initio theory because extrapolationsare dangerous

P.Navratil et al. Phys.Lett.B 704 379 (2011)




Synergy between experiment and predictive theory is essential





0 0.5 1 1.5 2 2.5Ekin [MeV]

0

5

10

15

20

25

30

35

40

S 17 [e

V b

]FilipponeStriederHammacheHassBabyJunghansSchuemannDavidsKikuchiDe04 MN E1NCSM/RGM E1

7Be(p,γ)8B

(a)

@TRIUMF

ab-initiophenomenology

NN from EFT�

Solar conditions cannot be reproduced in the Lab

Reaction cross sections are measured at higher energy than needed

Need a reliable ab-initio theory because extrapolationsare dangerous

P.Navratil et al. Phys.Lett.B 704 379 (2011)




• The TRIUMF TG is making leading contributions in subatomic physics

• The synergy between theory and experiment is an asset at TRIUMF

Conclusions and Outlook



• The TRIUMF TG is making leading contributions in subatomic physics

• The synergy between theory and experiment is an asset at TRIUMF

Conclusions and Outlook

Neutrons

Pro

tons

Nuclear Theory Future Goals

• Push the limits of ab-initio methods towards medium and heavy nuclei• Develop a unified description of structure and reaction properties• Understand the role of nuclear forces as one moves closer to the drip line

photo-fission

p on 238U

p on 238U

TRIUMF ISAC/ARIEL



Thank you!Merci!



• Cut on support for workshop and visitors Cut on Canada and World-wide connections as well as visibility

• Cut on support for RAs Decrease of group productivity/visibility

15

Reduced resources scenarios



• Cut on support for workshop and visitors Cut on Canada and World-wide connections as well as visibility

• Cut on support for RAs Decrease of group productivity/visibility

15

Reduced resources scenarios

Loss of Excellence and Synergies between Theory and Experiment


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Nuclear Theory at TRIUMF

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