This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University. Michigan State University designs and establishes FRIB as a DOE Office of Science National User Facility in support of the mission of the Office of Nuclear Physics.

Bradley Sherrill Director NSCL

FRIB: Experiment-Theory Coupling

§ Why do atoms exist?

§ Where do atoms come from?

§ What are atoms made of?

§ What are new and novel ways to use isotopes to solve societal problems?

Big Challenge: To answer these questions we need a predictive model of atomic nuclei and their interactions. The path to a predictive model is though theory. Ultimately, we need to be able to calculate nuclear properties better than we can measure them.

Big questions for nuclear science and the big challenge

B. Sherrill, FRIB Theory Alliance Inaugural Meeting , Slide 2

§ Experiments lead to discoveries – this will continue – these discoveries will yield the insights that lead to pioneering theory

§ Experiments test model predictions – discovering differences leads to improvements in our understanding

§ Experiments also provide • Parameters in, e.g. EFT or the shell model • Nuclear data for astrophysical models • Key nuclei for fundamental symmetry tests

§ Making the most exotic isotopes is extremely difficult (see the FRIB talk by T. Glasmacher) but when complete, FRIB will provide unprecedented reach.

§ Theory should provide • The ultimate goal – a predictive model • The tools to understand and interpret what can be measured • Guidance on where in the 7000 isotopes are the signals

Why do we need experiment (and for that matter FRIB)?

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§ Obvious trivial coupling - the “scientific method”

§ For science to work, we need all parts

Obvious experiment-theory coupling

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Nuclear Model

Prediction (or postdiction)

Experimental Results

Comparison to Model

Deduction Induction - Model revision

Theory to plan experiments

Additional theory to interpret experiments

Experiment-theory coupling in nuclear astrophysics

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Astrophysical Model

Calculation of observable

Astrophysical Observation

Comparison to Model prediction

Microphysics input (theory or data)

Induction – Model revision

Additional models to interpret observation

Predicted limits to the number of isotopes

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§  Estimated Possible: Erler, Birge, Kortelainen, Nazarewicz, Olsen, Stoitsov, Nature 486, 509 (28 June 2012), based on a study of EDF models

§  “Known” defined as isotopes with at least one excited state known (1900 isotopes from NNDC database)

§  Represents what is possible now

The number of isotopes available at FRIB

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§  Estimated Possible: Erler, Birge, Kortelainen, Nazarewicz, Olsen, Stoitsov, Nature 486, 509 (28 June 2012), based on a study of EDF models

§  “Known” defined as isotopes with at least one excited state known For Z<92 FRIB is predicted to make > 80% of all possible isotopes

A voyage of discovery

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§ FRIB has a chance to make something like 4500 isotopes, or 80% of all the ones possible for Z<92.

§ This process will be a voyage of discovery!

Graphics: Erin O’Donnell

§ Scientific community will depend on Theory Alliance and FRIB

§ Users are organized as part of the independent FRIB Users Organization (FRIBUO) • Chartered organization with an elected

executive committee • 1,460 members (102 U.S. colleges and

universities, 16 national laboratories, 50 countries) as of March 2016

• 19 working groups on instruments

1,400 scientists involved with the coupling

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www.fribusers.org

GRETA and HRS 60Ca example

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Simulation for 9Be(61Sc, 60Ca + γ) with GRETA

http://greta.lbl.gov/science/calcium

Crawford, Gade et al. GRETA – CD2 expected in 2017 HRS – CD0 soon

GRETA

Reaction theory (1n and 2n removal) and structure models are necessary for planning and interpretation of the results.

§ Observation of 6390.2 keV state in β-decay significantly changes calibration of nova thermometers and identification of presolar nova grains

§ Theory was key to plan and interpret

Recent example: experiment theory coupling

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Physics World

MSU-NDU-UT-ORNL-SIU collaboration

30S(p,γ)

§ Important input for DFT, understanding of Neutron Stars, etc. § Predictions for 84Ni range from 0.5 – 0.7 fm (see below) § How do we reliably extract skins when we have 1/s (or less) ?

Need reaction theory § Example:

Neutron skins

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Kortelainen, M. et al. Phys.Rev. C88 (2013)

208Pb

84Ni

Chemical history of the universe – the fossil evidence of the first stars

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⎟⎟⎠

⎞⎜⎜⎝

⎛=

Sunabundanceabundance

Starabundanceabundance

HFeHFeLOG

)/()/([Fe/H]

HERES Survey – Barklem et al. (2005)

Sun [Ba/Fe] = [Fe/H] = 0

§ By measuring the differences we learn about the history of the star – many new surveys

§ Barium (Ba) in early stars must be made differently from Iron (Fe)

§ See Aoki et al. SCIENCE 345 (2014) for a recent discussion

§ Complex problem; nuclear experiment is one part, theory the other

New data on elemental abundances: surveys and large aperture telescopes

§ The measurement of elemental abundances is at the forefront of astronomy using large telescopes

§ Large mirrors enable high resolution spectroscopic studies in a short time (Subaru, Hubble, LBT, Keck, …)

§ Surveys provide large data sets (Herschel, Apogee, SDSS, SEGUE, LAMOST, SkyMapper, LSST…)

§ Future missions: JWST - “The James Webb Space Telescope”, Gardner et al. Space Science Reviews: How did the Heavy Elements Form?

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Hubble Space

SUBARU

FRIB reach for T1/2, masses, and β-delayed neutron emission

N=82

N=126

Critical region probes: Main r-process parameters Production of actinides

Critical region probes: r-process freezeout behavior (Mumpower et al. 2012)

Critical region probes: Main r-process parameters Critical region probes:

Neutrino fluence

Different key-regions probe different model aspects when compared to observations Models needed •  (d,p) ↔ (n,gamma) •  T1/2, βn, BE,… •  Fission distributions

Critical region: Disentangle r-processes

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FRIB will enable measurement of much of the relevant nuclear physics (but not all)

H Schatz

, Slide 15

R-process nucleosynthesis near A=200 peak

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Maximum sensitivity to nuclear masses near the N=126 closed shell under various r-process trajectories.

Mumpower et al. J Phys G42 (2015)

Black line is FRIB limit

FRIB will measure many nuclides, but theory will be necessary for many others. Other example is fission of the heaviest nuclei for fission recycling.

• Angular correlations in β-decay and search for scalar currents o  6He and 18Ne at 1012/s

• Electric Dipole Moments o  225Ra, 223Rn, 229Pa (10,000x more

sensitive than 199Hg; 229Pa > 1010/s) • Anapole moment in Fr atoms

o  Understanding of weak interactions in nuclei (francium isotopes; 1010/s)

• Matrix elements for 0νββ • Experiments to validate theory • Double charge exchange

• Unitarity of CKM matrix o  Probe the validity of nuclear

corrections

Fundamental symmetries studies theory/experiment coupling

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e

γ

Z

212Fr

Adopted from Savard et al.

§ FRIB will have beams at 200 MeV/u, we need reaction theory that works at this energy (to get overlaps, B(GT), B(M1), matter distributions, etc.)

§ Reaction theory and structure theory need to be merged consistently. For example, how do we infer (n,γ) rates from nucleon transfer?

§ Many rare isotope beams will be at the per second level – need to calculate and interpret what we can measure

§ How do we recognize surprises? How do we distinguish parameter dependence from model deficiencies?

§ Experiments need models for context, planning, and interpretation. Configuration-Interaction models have been great at this. Continuation of the fruitful interaction is necessary.

Comments on experiment-theory coupling

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§ The FRIB Theory Alliance has a central role in reaching the goal of FRIB – A predictive model of atomic nuclei and their reactions.

§ Theory and experiment will have to have a close coupling § FRIB will provide unprecedented reach and give us the rare isotope

tools to answer the big questions § Experiments provide insight

• Discovery • Tests of models, determination of parameters in, e.g., EFT or the shell

model • Nuclear data for astrophysical models • Fundamental symmetry tests

§ Theory provides the context and models • The ultimate goal of a predictive model • The tools to understand and interpret what can be measured • Guidance on where in the 7000 isotopes are the signals

Summary

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