RecentdevelopmentsandperspectivesinNUCLEARSTRUCTURE

bygammaandparticlespectroscopy

SilviaLeoni

UNIMI/INFN:A.Bracco,F.Camera,F.C.L.Crespi,S.Bottoni,S.Leoni,A.Mentana,A.Pullia,S.Capra,S.Riboldi,P.F.Bortignon,G.Colò

INFN:G.Benzoni,B.Blasi,C.Boiano,S.Brambilla,B.Million,O.Wieland,E.Vigezzi

Milano,28-29June2017

INFN-CNS3-GAMMA:MI,PD,LNL,FI,PGInterna6onalcollabora6onswithinEUROPE,JAPAN,USA

INTRODUCTION

ChallengesinNuclearPhysics

o  ThePhysics–morethan7000Nuclei!o  Interdisciplinarity-Astrophysicso  DedicatedFacility/DetectionSetups–γspectroscopy

FOCUSonNUCLEARSTRUCTURESelectedRecentHighlights

o  ShapeCoexistenceo  CollectiveExcitations–Resonanceso  ComplexExcitations–CouplingParticlesandPhonons

o  OUTLOOK–howtopindownthenuclearforce…

...InterdisciplinarityAspects....

Very

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Neutron number N

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on n

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248Stable

~3000discovered

(EXOTIC)NUCLEI

OurChallenge:UNIFIEDDescriptionofALLNucleiintheUniverse

>7000estimatedtoexistintheUniverse

EnormousDiscoveryPotential!!!

BASICSCIENCE

ManyBodyQuantumSystem

SymmetryPrinciple

n p

EffectiveNuclearForce

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Neutron number N

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208Pb

132Sn

48Ca

78Ni

100Sn

16O Clusters Halos

DIPOLE

NeutronSKINOSCILLATIONExcitations

(EXOTIC)NUCLEI

SHELLStructureMagicNumbers

Shapes

BASICSCIENCE

ManyBodyQuantumSystem

SymmetryPrinciple

n p

EffectiveNuclearForce

OurChallenge:UNIFIEDDescriptionofALLNucleiintheUniverse

VERYCOMPACTOBJECT

upto~250nucleonsSIZE~10-45m3

DENSITY~1017kg/m3

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β-decay towards stable Isotopes

STRONGInterdisciplinarywith...ASTROPHYSICS

Rapid Capture of FREE Neutrons

… in STAR explosions

From EXOTIC To STABLE Nuclei

248Stable

BASICSCIENCE

ManyBodyQuantumSystem

SymmetryPrinciple

n p

EffectiveNuclearForce

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HeavyElementsABUNDANCES

dependsonStructureofUNKNOWNEXOTICNuclei

MagicNumbers,Shapes τβ Spherical~10xτβ Deformed

PnSpherical~0.5xPnDeformed

STRONGInterdisciplinarywith...ASTROPHYSICS

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APPLICATIONS

Radioisotopes,Reactors,…

BASICSCIENCE

ManyBodyQuantumSystem

SymmetryPrinciple

n p

EffectiveNuclearForce

RIKEN GANIL GSI ISOLDE-CERN Orsay ILL-Grenoble Bucharest LAB Legnaro LAB Sud LAB Gran Sasso

MSU Argonne

TRIUMF

AWorldWideEfforttoExpandtheNuclearChart…•  PRODUCTION:stableandradioactiveionbeams,neutronbeams,…

TheoryInstituteofNuclearPhysicsSEATTLE(USA)

TheoryECT*EuropeanCenterTRENTO(ITALY)

OSAKA

•  INVESTIGATIONofNuclearStructure:gammaandparticlespectroscopy

LONGTRADITIONOFγ-SPECTROSCOPYArraysbasedonComptonsuppressedGedetectors

EUROBALL Legnaro, Strasbourg

EUROGAM Daresbury

GASP Legnaro

Star@ngfromthe80’s:TESSA(Daresbury)OSIRIS(Berlin)ARGONNE-NDARRAY(Argonne)NORDBALL(Copenhagen)JUROSPHERE(Jyvaskyla)EUROGAM(Strasbourg)CLARION(OakRidge)GASP/GALILEO(Legnaro)EUROBALL(Legnaro,Strasbourg)GAMMASPHERE

AGATA(Advanced-GAmma-Tracking-Array)

LNL, 2011 S.Akkoyunetal,NIMA668(2012)26-58

GRETA(Gamma-RayEnergyTrackingArray)

LBNL, 2011 S.Paschalisetal,NIMA709(2013)44-55

STATEoftheARTGeARRAYS

The“Ul@mate”GeArrays²  EFFICIENCY:43%Mγ=1and28%Mγ = 30 (@1MeV,FULLBALL)²  COUNTRATEcapabiliRes(100sKHz)²  ANGULARRESOLUTIONoftheγinteracRonpoint(θ~1o)²  “PERFECT”DOPPLERCORRECTION(6keV@1MeV,β=50%)

SOFTWARE

TheGammaTrackingArrayConceptHARDWARE

LNL: 2010-2011 15 crystals (5TC) Total Eff. ~6%

1/12 FULL BALL

AGATAInauguration:9thApril2010–LegnaroNationalLaboratoryINFN

Legnaro

PhysicsCampaign@LNL(2010-2011)MostRelevant

ResultsfromMilano2Phys.Rev.Lett.1ReviewPaper

SeveralPhys.Rev.C

LNL: 2010-2011 15 crystals Total Eff. ~6%

Demonstrator + PRISMA “backward”

STABLEBEAMS20experiments

GANIL: 2015-2019 up to 45 crystals Total Eff. ~22%

AGATA+VAMOS+ … “backward” EXOTIC(ISOL)

&STABLEBEAMS6experimentsin2015

GSI: 2012-2014 22 crystals Total Eff.~10%

AGATA + FRS “forward”

RELATIVISTICEXOTICBEAMS7experiments

àFrom2020atLegnaro-INFN(SPESRadioac@veISOLBeams)

TheAGATAEvolu@onTowards1π

MILANOLaBr3Detectors

AGATA-FULLDetector180crystalssegmented(6480segments)60tripleclusters2.5tonsFULLYDIGITALelectronics

Solid ang. 82% Eff. 43% (Mγ=1) P/T 58% (Mγ=1)

A.Bracco,Chair

Detection Systems (State of the Art )

neutron identification

NEDA/NWALL

charged-particle Spectroscopy

Si stripped/pixel detectors

TREX MUGAST

Magnetic Spectrometer Large Acceptance

PRISMA VAMOS

GALILEO – LNL

AGATA

Gamma spectroscopy HPGe, scintillators

PARIS Labr3+NaI

MINIBALL

EXOGAM

Very Powerful and Complete Experimental Setups ...

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208Pb

132Sn

48Ca

78Ni

100Sn

16O

DIPOLE

NeutronSKINOSCILLATION

ExcitationsPygmyResonances

ShapeCoexistenceNi-isotopes

SelectedRecentHighlightsofγspectroscopy

CouplingsParticle-Phonon133Sb=132Sn+1proton

AppearenceofDIFFERENTSHAPESintheSAMENUCLEUSatlowexcitationenergy

SHAPEISOMERSinac@nideA=240Polikanov–1973

TWOSEPARATEWORLDS

5%

γ95% 10-7 W.u.

SecondaryMinimainthePotentialEnergySurface–PESMETASTABLEConfigurations

ConformationalISOMERButaneMolecule

C4H10

FREE

Ene

rgy

PresentChallengeinNuclearPhysics:MICROSCOPICdescriptionEmergenceofSHAPESandDEFORMATION

inapureSHELLModelframework(individualnucleons+interaction)

ShellStructureforpandn

2ħω

3ħω

4ħω

5ħω

6ħω

0ħω

1ħω2

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DivergentDimensionofConfigurationSpace

NumberofwaystodistributeAnucleonsoverKorbitals

MICROSCOPICStructureofNuclei:acomputationalchallenge…

N=Z

2244Ti ≈104 2448Cr ≈107 2856Ni ≈1010

4488Ru≈1028

Numberofconfigurations

State-of-the-artSHELLModel

possibleforA<100

newcalculationsschemeMonteCarloApproachEffectiveN-Ninteraction

verypowerfullcomputer

106parallelprocessors

K-ComputerTokioUniversity

(Prof.TakaOtsuka’sgroup)

MonteCarloSHELLModel(T.Otsuka’sGroup)66Ni–70Ni:COEXISTENCEofspherical,oblateandprolateSHAPES

2974 0+4

1549

66Ni

1425

2971 3+

1546

2+

0+326712443 0+2

10181245

1425

0+1

ConfirmedbyExperiment!!!18O+64Nià16O+66Ni,belowCoulombbarrier

prolate

spherical oblate

Sphericalg.s.

à 20(7) ps 0.2 W.u.

BestCandidateforSHAPEisomerism

HINDEREDγ-decay

PROLATEàSPHERICAL

66Ni

S.Leoni,B.Fornaletal.,Phys.Rev.LeJ.118,162502(2017)–Editor’sSugges6on

STEPFORWARDinunderstandingMICROSCOPICoriginofdeformationàVALIDATIONofPREDICTIVEPOWERofMostAdvancedSHELLModelpredictions

ComplementarystudiesinNichainbyβ-decay:G.Benzonietal.,…

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208Pb

132Sn

48Ca

78Ni

100Sn

16O

DIPOLE

NeutronSKINOSCILLATION

ExcitationsPygmyResonances

ShapeCoexistenceNi-isotopes

SelectedRecentHighlightsofγspectroscopy

GIANT

PYGMY RESONANCESn

SnFew%

TheDIPOLEResponseInNucleiSTRONGImpact

onElementAbundance

Exp

Theory

withpygmy

RelevantENERGYwindowfor(γ,n)reactions

inSTARS

RelevantforNEUTRONSTARSRadiiNeutronPressurefromSKIN

ASTROPHYSICSImplications

o  Nucleosynthesiso  NeutronStars

RelevanceinNuclearStructure

o  ComplexMicroscopicNature

LNLCampaign

AGATA+SiTelescopes+

Scintillators(LaBr3)

17O@20MeV/Aon208Pb,124Sn,90Zr,140Ce

STABLEtargets

PygmyResonancesinSTABLENUCLEIHeavy-IonInelasticScattering:aprobesensitivetothesurface

ΔE-Epixeltelescopes

PygmyStrength(E1)1-3%EWSRisoscalarE1

SeePOSTERF.Crespi

ANEWOBSERVATION:124Sn–QUADRUPOLEPYGMY

Multitudeof2+discretestates

AGATA

E1

E2

124Sn(17O,17O’γ)

ConcentraRonofE2StrengthmuchbelowtheGIANTQUADRUPOLEresonance-InagreementwithQuasi-phononModelpredicRons-

GQR

A.Bracco,F.Crespi,E.Lanza,Eur.Phys.J.A51(2015)99

ReviewPaper

PygmyResonancesinEXOTICNUCLEIRelativisticCoulombExcitation:highselectivityforE1excitation

Ion Source

3-20 MeV/nucleon (8-20% c)

Up to

1 GeV/nucleon (90% c)

Experimental Area

GSI

2012-2014

O.Wieland,A.Braccoetal.,PRL102,092502(2009)

PYGMYStrength:5-9%EWSR

68Ni

FIRSTCase:EUROBALL+BaF2Setup

R.Avigo,O.Wieland,…inpreparation

64Fe Preliminary…

AGATA+LaBr3Setupv/c=73%

Abovebackground

ComplementaryprogramatRIKEN-JapanPYGMYstudiesintheMOSTEXOTICNuclei:20,22,24O,50,52Ca,70,72Ni,128,132Sn

NiCa

OngoingExperimentalCampaign…(A.Bracco,F.Camera,F.Crespi,O.Wieland,…)

Analysis

8largeLaBr3(Milano)ε=1-2%@10MeV

DALI2–160NaIε=4%@10MeV

EvolutionofPYGMYstrengthalongisotopicchains

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208Pb

132Sn

48Ca

78Ni

100Sn

16O

DIPOLE

NeutronSKINOSCILLATION

ExcitationsPygmyResonances

ShapeCoexistenceNi-isotopes

SelectedRecentHighlightsofγspectroscopy

CouplingsParticle-Phonon133Sb=132Sn+1proton

Particle-PhononCouplings

KeyIngredientfor:-Anharmonicityofvibrationalspectra-DampingofGiantResonances

àemergenceofCOMPLEXexcitations

Commonmany-bodydiagrammatictechniquesDifferentenergyscales…

132Sn (phonon)

133Sb=132Sn+1proton

133Sb

CouplingsbetweenParticleandCollectiveDegreesofFreedom

InNUCLEI

132Sn

PHONONS=VibrationsofMAGICCore

Electron-PhononCouplings

KeyIngredientfor:-ElectromagneticResponse-SuperconductivityinMetalClusters,Fullerenes,…

InCONDENSEDMATTER

PhononsandPlasmons

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Particle-PhononCouplingsaroundEXOTICandDoublyMagic132Sn

n+235Un+241Pu

Neutron-inducedFISSION

n+235Un+241Pu

132Sn 132Sn

78Nir-process

133Sb:132Sn+1π

One-valenceProtonnucleus

133Sb

Theγ-spectroscopycampaign@ILL-Reactor(Grenoble)2012-2013:100days,95%DATAtaking

Dedicatedballis@cneutronguidehighlycollimatedbeam(1cm2)

coldneutrons(meV)Φn=2×108ncm-2s-1

58MW

10 EXOGAM 6 Ge GASP

MOSTINTENSECon@nuumneutronsource

Inpile

Φn=5×1014ncm-2s-1

FissionData

17µs < 20 ps 31(8) ps

LifeRmemeasurementswithfastscinRlltors

133Sb=132Sn+1proton

B(M1) [W.u.]

15/2+à13/2+0.24

13/2+à11/2+0.004 !!

InterpretationNOTDoablebySHELLModel:

TooLARGEspace

NatureoftheStatesisCOMPLEXandDIVERSE

àAlternaRveApproach

133Sb:132Sn+1π

TheNew“HYBRID”Model(G.Colò,P.F.Bortignon-Milano)COREExcitaRons(Phonons-RPA)+singleparRcle(HartreeFock)

Coupling

MatrixElementsbetween

SINGLEPARTICLEand

COREexcitations

consistentlycalculated

RPA(SkyrmeX) HartreeFock(SkyrmeX)

Phononsandlesscollectiveexcitations

Coupling

⊗

NOFREEPARAMETERS-SameSkXInteraction

G. Colò, P.F. Bortignon, G. Bocchi, Phys. Rev. C 95, 034303 (2017)

133Sb:132Sn+1π

TheNew“HYBRID”Model(G.Colò,P.F.Bortignon-Milano)COREExcitaRons(Phonons-RPA)+singleparRcle(HartreeFock)

B(M1)fromlifetimes

o  GOODReproductionofExp.o  MIXEDStatesbasedonCollectiveandNon-CollectiveExcitationsof132SnCORE

G.Bocchi,S.Leoni,B.Fornaletal.,…Phys.Lett.B760, 273 (2016)

2016HIGHLIGHTInstitutLaue-Langevin(ILL)

STARTINGPOINTforextendedinvestigationinMEDIUM/HEAVYNucleiNOTpossiblewithSHELLMODEL!!!

SeePOSTERS.Bottoni

OUTLOOK:pinningdowntheNATUREofthenuclearforce

InHEAVY-Systems:EffectiveN-NInteraction

CorrectionsareneededduetothepresenceofotherNucleons

QCD

BareN-NinteractioncanbederivedfromQCD

LIGHTsystemsONLY(uptoC,O,Ne,…)canbecomputedbyab-initiocalculations:àtheyaresensitivetodetailsoftheN-Ninteraction(2bodyand3bodyterms)

MajorprobleminNuclearPhysics:detailcompositionofthenuclearforceisNOTknown!!!

τ(2+)0.25ps0.08ps2body3body

16C

AGATAexp.inGANIL-in10days:

18O(141MeV)+238U(10mg/cm2)

γ-spectroscopyofn-richB-C-O-Fnuclei

HighPrecisionLifetimesmeasurementsτ =100fs–10’sps

Conclusions

o  NUCLEARSTRUCTUREPHYSICSaimsataunifieddescriptionof>7000NucleiintheUniverse

lessthanhalfareknown...veryhighdiscoverypotential!!!

MicroscopicOriginofshapesanddeformationsNatureofResonanceExcitations– neutronskins…Emergenceofcomplexexcitations–particle-phononcouplings…

Outlook:sensitivitytodetailsofnuclearforce

o  StrongInterdiciplinarity–Astrophysics

o  AMajorChallengeforTHEORY…

o  State-of-the-ArtSETUP:AGATA,largevolumescintillators,…

o  SeveralBASICquestionstobeanswered

**ThankYoufortheAttention**