Nuclear Reaction Studies with radioactive ion beams for Stewardship Science

NRS4SS

SSAP SymposiumFebruary 26-27, 2020

Jolie A. CizewskiRutgers University

DOE SSAA DE-NA0003897

SSAP Feb 2020

Nuclear Reaction Studies for Stewardship Science

§ NRS4SS project inaugurated April 1, 2019§ Builds on 16 years of Center of Excellence for

Radioactive Ion Beam Studies for Stewardship Science (RIBSS)

§ Alumni of RIBSS Center§ Staff members at LLNL and LANL§ Staff members at ORNL§ Faculty members

§ University of Tennessee§ Michigan State University

§ Postdocs at LLNL§ Key collaborators on current NRS4SS project

SSAP Feb 2020

Peer-reviewed publications 2019-20§ Peer reviewed publications

§ 9 manuscripts have been published or are in press § 2 submitted, +2 close to submission

§ Other products: Over 10 invited talks have been presented.

§ Highlights (with g.s. key author)§ Direct Neutron Capture on Tin Isotopes Near the N = 82

Shell Closure, B. Manning et al., Phys. Rev. C 99, 041302 (R) (2019); Phys. Rev. C 99, 069901 (E) (2019)

§ Spectroscopic factors near the r-process path using combined measurements: 86Kr(d,p)87Kr, D. Walter, et al., Phys. Rev. C 99, 054625 (2019).

§ The ORNL Deuterated Spectroscopic Array – OdeSA, M. Febbraro, R. Toomey et al., Nucl. Instrum. Method Phys. Res. A 946, 162668 (2019).

SSAP Feb 2020

NRS4SS Students & Postdocs§ Who is supported and their position

§ Graduate students (3):§ Heather Garland*, Harry Sims*, Rebecca Toomey*

§ SSGF: Chad Ummel*§ Postdoc: Gwen Gilardy Seymour

*making poster presentations§ NNSA-student interactions – numerous

§ Spring 2019: LLNL staff members participated in experiments at ATLAS§ Andrew Ratkiewicz (LLNL) is key to realizing the experiments

and worked closely with Rutgers students & postdoc§ August 2019, LLNL: 3 days of workshops & collaboration meetings§ October 2019, ORNL: Andrew Ratkiewicz (LLNL) visited ORNL for

collaboration meetings

SSAP Feb 2020

NNSA interactions: LLNL workshops, Aug 2019§ Talks and poster presentations by Rutgers students &

postdocs§ Talks by LLNL scientists: Nuclear experiment and theory

overviews, planetary defense, nuclear counter terrorism, quest for ignition at NIF

§ Tours of nuclear experimental and decay facilities§ Analysis & planning meetings with LLNL scientists

SSAP Feb 2020

AdministrativePOC:ShannonFontes<fontes9@llnl.gov>,925-423-7068LLNL-MI-783277

StewardshipScienceAcademicAlliance(SSAA)Meeting

Tuesday,August13,2019B151StevensonRoom(unlessotherwiseindicated)

Time Title+Speaker8:00a.m. WestGateBadgeOfficeforbadging;thencaravantoB151andpostersetup8:30a.m. SecuritybriefingforForeignNationals:AndrewRatkiewicz SessionChair:ErichOrmand9:00a.m. WelcometoSSAAworkshopandOverviewofnuclearreactionsfor

StewardshipScience:JolieCizewski(RutgersUniv.)9:30a.m. WelcometoLLNLandoverviewofnuclearscienceexperimentefforts:

RonSoltz(LLNL)10:00a.m. LLNLNuclearReactionTheoryResearchforAstrophysicsandLab

Applications: JuttaEscher(LLNL)10:30a.m. Break SessionChair:TeresaBailey10:45a.m. Informingweakr-processnucleosynthesiswithORRUBAatNSCL:

HarrySims(RutgersUniv.)11:05a.m. Developingtechniquestomeasuresurrogatereactionswithbeams

andGODDESS:HeatherGarland(RutgersUniv.)11:25a.m. InformingNovaNucleosynthesiswithGODDESS:18F(p,a)15Oand

38K(p,g)39Ca:MattHall(ORNL) 11:45p.m. TheStructureof10Nand9CUsingtheActiveTargetApproach,Josh

Hooker(Univ.ofTennessee)12:05p.m. LunchandPosterSession SessionChair:PeterBedrossian1:00p.m. Measurementofthe7Li(a,g)crosssectionatnu-processtemperature:

GwenaelleGilardy(RutgersUniv.) 1:20p.m. BEARTrap:ANewDedicatedSetupforBeta-delayedNeutronStudies:

GemmaWilson(LouisianaStateU.)1:40p.m. DevelopmentofaHybridTechniqueforNeutronSpectroscopywith

ODeSA:RebeccaToomey(RutgersUniv.) 2:00p.m. Developmentofaneutrondetectorwithtrackingcapabilities(NEXT):

JoeHeideman(Univ.ofTennessee)2:20p.m. IntroductiontoBuilding194–NeutronImaging:BrianRusnak(LLNL)2:40p.m. SurrogateReactionsusingHyperionandNeutronSTARS:JasonBurke

(LLNL)3:00p.m. BreakandcaravantoBldg1943:30p.m. TourofBuilding194facilities6:00p.m. GroupDinner

LemonGrassThaiRestaurant,Livermore(tentative)

AdministrativePOC:ShannonFontes<fontes9@llnl.gov>,925-423-7068LLNL-MI-783277

StewardshipScienceAcademicAlliance(SSAA)Meeting

Wednesday,August14,2019B151StevensonRoom(unlessotherwiseindicated)

Time Title+Speaker SessionChair:KayKolos9:00a.m. PlanetarydefenseatLLNL:RobManagan(LLNL)9:30a.m. NuclearCounterTerrorismApplications:JoRessler(LLNL)10:00a.m. Approachingaburningplasmaonthequestforignition

NIF:DanCasey(LLNL)10:30a.m. Break SessionChair:RichardHughes11:00a.m. Closingremarks:AndrewRatkiewicz(LLNL)andJolieCizewski(Rutgers)11:15a.m. RadioactivitycountingcapabilitiesinB151:KeenanThomas(LLNL)11:30a.m. TourofNuclearCountingFacilityinB151Noon Meetingends

August13,2019Posters

Name Institution Poster title

Josh Hooker Univ of TN-Knoxville Ionization Chamber Development for VANDLE

Joe Heideman Univ of TN-Knoxville Correlating Neutron Time-of-Flight with Interaction Position using NEXT

Matt Hall Oak Ridge National Lab Designing a Supersonic Gas Jet Target for Orbital Spectrometers

Rebecca Toomey Rutgers University Development of a Hybrid Technique for Neutron Spectroscopy with ODeSA

Heather Garland Rutgers University Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies

Gwenaelle Gilardy Rutgers University Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies

Chad Ummel Rutgers University GRETINA-ORRUBA: Dual Detectors for Experimental Structure Studies

Rajesh Ghimire Univ of TN-Knoxville GRETINA-ORRUBA: Dual Detectors for Experimental Structure Studies

Harrison Sims Rutgers University Measuring nuclear reactions with fast rare isotope beams and ORRUBA

SSAA-LLNL Workshop August 2019

SSAP Feb 2020

Nuclear reaction studies with radioactive ion beams to inform

nucleosynthesis in stars & explosions

SSAP Feb 2020

§ Slow neutron capture§ Takes place in later

stages of stellar burning§ s process

nucleosynthesis§ Along stable nuclei

§ Believed to take place in supernova explosions and/or binary neutron star mergers

§ r process nucleosynthesis§ Far from stability

Synthesis of heavy elements: rapid neutron capture in stellar explosions

http://www.nasa.gov/centers/marshall/multimedia/photos/2004/photos04-222.html_prt.htm

users.monash.edu.au

SSAP Feb 2020

ANRV352-AA46-08 ARI 15 July 2008 11:46

2. HEAVY ELEMENT FORMATIONStellar fusion of elements heavier than iron is endothermic: It requires energy. Also, Coulombbarriers for charged-particle reactions increase at heavy proton number. As a result, the nucleibeyond the Fe group are generally not formed in charged-particle fusion but instead are createdin n-capture processes; there are no Coulomb barriers. Neutrons are captured onto nuclei thatcan then ! decay if they are unstable, transforming neutrons into protons. In this manner, elementproduction progresses through the heaviest elements of the Periodic Table. This process is definedas slow (rapid) if the timescale for neutron capture, " n, is slower (faster) than the radioactive decaytimescale, for unstable nuclei. Generally we refer to these as the s-process or the r-process.

The r-process and s-process were initially described and defined in 1957 by Burbidge et al.(1957) and Cameron (1957a,b). The s-process ("n ! "! ) is defined by virtue of the long times(hundreds or thousands of years) between successive neutron captures on target nuclei. It thusoperates close to the so-called valley of !-stability, as illustrated in Figure 1 (Moller, Nix &Kratz 1997, their figure 16). Consequently the properties (e.g., masses and half-lives) of the stableand long-lived nuclei involved in the s-process can be obtained experimentally. As the s-process

–2.5–2.0–1.5–1.0–0.5

0.00.51.080

10–2

10–1

100

101

100

120

140160

180

Mass number (A)

r-process abundance

200

Neutron number (N)

00 20 40 60 80 100 120

log(T s–1)

140 160

20

40

60

80

100

120

Nr, (Si = 10 6)

Pro

ton

nu

mb

er (

Z)

Figure 1Chart of the nuclides showing proton number versus neutron number after Moller, Nix & Kratz (1997).Black boxes indicate stable nuclei and define the so-called valley of !-stability. Vertical and horizontal linesindicate closed proton or neutron shells. The magenta line indicates the so called r-process path, with themagenta boxes indicating where there are final stable r-process isotopes. Color shading denotes thetimescales for ! decay for nuclei and the jagged black line denotes the limits of experimentally determinednuclear data at the time of their article.

www.annualreviews.org • Neutron-Capture Elements in the Early Galaxy 243

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r-process nucleosynthesis abundancesPeaks near U fission yield; unknown (n,g) rates important

Sneden, Cowan, Gallino, Annu. Rev. Astron. Astrophys. 46:241-288 (2008)

N=50 N=82

N=126

N=50N=82

N=126

9

SSAP Feb 2020

r-process (n,g) sensitivities from Mumpower et al., PPNP 86 86-126 (2016)

Unknown (n,g) rates impact r process abundances

Adopted from A. Ratkiewicz (CNR, 2018)

SSAP Feb 2020

Nuclear reaction studies with radioactive ion beams to inform stockpile stewardship science

SSAP Feb 2020

Nuclear reaction data for stewardship science§ Need high quality nuclear data to interpret nuclear test

results§ In particular: Unknown (n,g) rates on short-lived fission

products that decay to longer lived isotopes that are measured

§ Example of measurement: § Production of 144Ce (t1/2=285 days)§ Daughter of prompt fission products 143,144Ba§ Nuclei created or destroyed by (n,g), (n,2n), or (n,p) reactions

in high-neutron-fluence environments prior to b decay.

SSAP Feb 2020

Motivation: stewardship science

• Intense fission fragments:• 143Ba and 144Ba

• Stewardship science interest [Hof18]• Although decay to 144Ce:

• Created through e.g. (n,g)• Destroyed through, e.g. (n,2n)

SSAP Feb 2020

Motivation: stewardship science

• Intense fission fragments:• 143Ba and 144Ba

• Stewardship science interest [Hof18]• Although decay to 144Ce:

• Created through e.g. (n,g)• Destroyed through, e.g. (n,2n)

SSAP Feb 2020

Motivation: stewardship science

• Intense fission fragments:• 143Ba and 144Ba

• Stewardship science interest [Hof18]• Although decay to 144Ce:

• Created through e.g. (n,g)• Destroyed through, e.g. (n,2n)

Away from stability, calculations of neutron capture rates can vary by orders of magnitude depending on the model used

SSAP Feb 2020

Nuclear reaction studies with radioactive ion beams as

surrogate for neutron capture

SSAP Feb 2020

Connecting nuclear reactions & neutron capture:Validating surrogate for neutron capture on rare isotopes

17

Synergistic collaboration between LLNL experimentalists & theorists and RIBSS Center scientistsPhysicalReviewLetters122,052502(2019)

Towards Neutron Capture on Exotic Nuclei: Demonstrating !d;p!"as a Surrogate Reaction for !n;!"

A. Ratkiewicz,1,2,* J. A. Cizewski,2 J. E. Escher,1 G. Potel,3,4 J. T. Burke,1 R. J. Casperson,1

M. McCleskey,5 R. A. E. Austin,6 S. Burcher,2 R. O. Hughes,1,7 B. Manning,2 S. D. Pain,8

W. A. Peters,9 S. Rice,2 T. J. Ross,7 N. D. Scielzo,1 C. Shand,2,10 and K. Smith111Lawrence Livermore National Laboratory, Livermore, California 94550, USA

2Department of Physics and Astronomy, Rutgers University, New Brunswick, New Jersey 08901, USA3Michigan State University, East Lansing, Michigan 48824, USA

4Facility for Rare Isotope Beams, East Lansing, Michigan 48824, USA5Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA

6Astronomy and Physics Department, Saint Mary’s University, Halifax, NS BH3 3C3, Canada7Department of Physics, University of Richmond, Virginia 23173, USA

8Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA9Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831, USA

10Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom11Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA

(Received 15 June 2018; revised manuscript received 9 November 2018; published 7 February 2019)

The neutron-capture reaction plays a critical role in the synthesis of the elements in stars and is importantfor societal applications including nuclear power generation and stockpile-stewardship science. However, itis difficult—if not impossible—to directly measure neutron capture cross sections for the exotic, short-livednuclei that participate in these processes. In this Letter we demonstrate a new technique which can be usedto indirectly determine neutron-capture cross sections for exotic systems. This technique makes use of the!d; p" transfer reaction, which has long been used as a tool to study the structure of nuclei. Recent advancesin reaction theory, together with data collected using this reaction, enable the determination of neutron-capture cross sections for short-lived nuclei. A benchmark study of the 95Mo!d; p" reaction is presented,which illustrates the approach and provides guidance for future applications of the method with short-livedisotopes produced at rare isotope accelerators.

DOI: 10.1103/PhysRevLett.122.052502

Essentially all of the heavy elements are synthesized inastrophysical environments by processes that involveneutron capture. The slow neutron-capture process (the sprocess) occurs predominantly in the low neutron flux inAGB stars, yielding a nucleosynthesis path that typicallydeviates only one or two neutrons from ! stability. Incontrast, the rapid neutron-capture process (the r process)involves exotic neutron-rich nuclei and requires explosivestellar scenarios with high neutron fluences. The r processis responsible for the creation of roughly half of theelements between iron and bismuth and synthesizes heavynuclei through the rapid production of neutron-rich nucleivia neutron capture and subsequent ! decay.The recent observation of the gravitational waves

associated with a neutron-star merger [1], and the sub-sequent kilonova understood to be powered by the decayof lanthanides [2,3], demonstrated that neutron-star merg-ers are an important r-process site, especially for theheaviest elements. However, r-process abundance patternsare sensitive to astrophysical conditions (cf. [4]). In a“cold” r process (which could occur in a neutron star

merger or with the highly accelerated neutrino-drivenwinds following a core-collapse supernova), neutroncapture !n; "" and photo-dissociation !"; n" are not inequilibrium, so the rate at which neutron capture proceedswill affect the final r-process abundance pattern. Thetimescales of the cold r process are such that competitionbetween neutron capture and ! decay occurs during thebulk of the r-process nucleosynthesis. Neutron-capturerates on unstable nuclei affect the final observed abun-dance patterns even in the traditional “hot” r process(thought to occur in the neutrino-driven winds in a proto-neutron star resulting from a core-collapse supernova)during the eventual freeze-out, when !n; ""!!"; n" equi-librium no longer occurs. Accordingly, neutron capture isinfluential in determining the final r-process abundancepattern, especially beyond the !n; ""!!"; n" equilibrium.Therefore, measuring !n; "" rates on key neutron-richnuclei continues to be an important component in under-standing r-process abundance patterns and constrainingthe astrophysical sites for r-process nucleosynthesis as afunction of mass [5].

PHYSICAL REVIEW LETTERS 122, 052502 (2019)

0031-9007=19=122(5)=052502(7) 052502-1 © 2019 American Physical Society

SSAP Feb 2020

Z A N

Z A+1 N+1

≈m

any

leve

ls≈

Sn≈ 7 MeV

(n,g)

A(n,g)(A+1)§ Cross section vs neutron

energy depends upon product of cross section of formation of compound nucleus AND decay of the compound nucleus§ For each spin,parity

§ Theorists can calculate formation; difficult to calculate decay

€

σnγ (En ) = σnCN

J ,π∑ (En ,J,π )Gγ

CN (En ,J,π )

SSAP Feb 2020

Surrogate reaction concept &Hauser-Feshbach formalism

A

“Surrogate”reaction

dp

A+1*

An

“Desired” reaction

A+1g

Compound nucleus

(n,g) cross section: product of compound nucleus formation and decay for every spin and parity:

σ nγ (En)= σ nCN

J ,π

∑ (Ex ,J,π )GγCN (Ex ,J,π )

Z A N

Z A+1 N+1

≈ man

y le

vels

≈

Sn≈ 7 MeV

(n,g)

SSAP Feb 2020

Surrogate reaction concept &Hauser-Feshbach formalism

A

“Surrogate”reaction

dp

A+1*

An

“Desired” reaction

A+1g

Compound nucleus

Surrogate particle-gamma coincidence: product of compound nucleus formation and decay for every spin and parity:

Ppγ (Ex ,θ)= FdpCN

J ,π

∑ (Ex ,J,π ,θ)GγCN (Ex ,J,π )

(n,g) cross section: product of compound nucleus formation and decay for every spin and parity:

σ nγ (En)= σ nCN

J ,π

∑ (Ex ,J,π )GγCN (Ex ,J,π )

6+4+

2+

0+

Z A N

Z A+1 N+1

≈ man

y le

vels

≈(d,pg)

Z A N

Z A+1 N+1

≈ man

y le

vels

≈

Sn≈ 7 MeV

(n,g)

SSAP Feb 2020

Surrogate (n,g) with (d,pg)

Ppγ (Ex ,θ)= FdpCN

J ,π

∑ (Ex ,J,π ,θ)GγCN (Ex ,J,π )

(d,p) reaction forms compound nucleusv Need to measure P(d,pg)v Need theory to calculate FCN

v Need to deduce GCN by fit to P(d,pg) accounting for FCN

Validated with 95Mo(d,pg)96Mo reaction

s(n,g) was measured and evaluated

SSAP Feb 2020

95Mo(d,pg): Input for GCN(Ex,J,p)

Surrogate (d,pg) dataMeasure Ppg

Sn

Ppγ (Ex ,θ)= FdpCN

J ,π

∑ (Ex ,J,π ,θ)GγCN (Ex ,J,π )

SSAP Feb 2020

95Mo(d,pg): Input for GCN(Ex,J,p)

Surrogate (d,pg) data

G. Potel et al, PRC 92, 034611(2015)

Potel: 96Mo spin distribution

Sn

Ppγ (Ex ,θ)= FdpCN

J ,π

∑ (Ex ,J,π ,θ)GγCN (Ex ,J,π )

SSAP Feb 2020

95Mo(d,pg): Input for GCN(Ex,J,p)

Surrogate (d,pg) data

G. Potel et al, PRC 92, 034611(2015)

Potel: 96Mo spin distribution

Sn

Ppγ (Ex ,θ)= FdpCN

J ,π

∑ (Ex ,J,π ,θ)GγCN (Ex ,J,π )

HF calculations (Jutta Escher)§ FCN from Gregory Potel§ Bayesian fit to observed P(d,pg)

§ Level density: Gilbert & Cameron§ No norm to D0

§ Lorentzian g strength function; § No <G(g)>

Ø GCN(Ex,J,p)

SSAP Feb 2020

Fits to Gamma Emission Probabilities Constrain Hauser Feshbach Parameters for (n,g)

Calculation

Sn

SSAP Feb 2020

Determining the (n,g) cross section –need to include spin-parity in surrogate channel.

Ratkiewicz et al., Phys. Rev. Lett. 122, 052502 (2019)

(No Jπ dependence)

SSAP Feb 2020

GODDESS at ATLAS§ Neutron capture (n,g) reactions on fission fragments

important for§ Synthesis of heavy elements in stellar explosions§ Stockpile stewardship science

§ Demonstrated (d,pg) reaction is valid (n,g) surrogate§ Need

§ Radioactive ion beams: 252Cf fission fragment beams at ATLAS§ Light ion detector array

§ Oak Ridge Rutgers University Barrel Array (ORRUBA)§ Previous SSAA Center: Developed, enhanced & exploited

§ High-efficiency, high-resolution gamma-ray detection§ Gammasphere (2015) and GRETINA (2019) campaigns at ATLAS

§ Beam-like recoil detectionØGODDESS: Gamma-array ORRUBA: Dual Detectors for

Experimental Structure Studies

SSAP Feb 2020

GODDESS: GRETINA ORRUBA Dual Detectors for Experimental Structure Studies

(d,pg) with radioactive beams

Gamma-Ray Energy Tracking In-Beam Nuclear Array

Early 2019 campaign

SSAP Feb 2020

GODDESS 2019:Rutgers, LLNL, ORNL, U Tenn Knoxville collaboration

29

SSAP Feb 2020

Summary NRS4SS Project§ First-year activities

§ Four grad students + 1 postdoc actively engaged in research and interacting with LLNL scientists

§ Milestone: coupling ORRUBA to GRETINA & 1st campaign§ 3 days of workshops and collaborative meetings at LLNL§ Submitted experiment proposals for future measurements at

ATLAS and at NSCL with ReA beams § Focused on analyzing data

§ Second-year plans§ Preparing for coupling ORRUBA to GRETINA for fast-beam

80Ge (d,pg) measurements at NSCL (National Superconducting Cyclotron Laboratory)§ Scheduled to run in June 2020 w/ LLNL and ORNL collaborators§ Model for day-1 Facility for Rare Isotope Beams (FRIB) experiments

§ Preparing for 3-day August 2020 meetings at LLNL

SSAP Feb 2020

Thank you for your attention

Work supported in part DOE SSAA DE-NA0003897, Stewardship Science Graduate Fellowship and National Science Foundation