Neutronskinstructureandshellevolution - - PowerPoint PPT Presentation

• Physics &Instrumentation,Firenze,1418January 2008

Neutronskinstructureandshellevolution

• fweaklyboundneutronrichEURISOLnuclei

incoupledreactionchannelstudies

Probethestructure&spectroscopy at largeisospin Measure unbound states detection devices Requirements foranewexperimental setup

ρ ,ρ

GOALwith EURISOL:extended systematics ofneutronrms radiusandof neutronexcitation along isotopic chains Structurestudies at thedriplines :exemples,+exptheory

NEEDFORANIMPROVEDTHEORETICALFRAMEWORKOFSTRUCTUREANDREAC NEEDFORANIMPROVEDTHEORETICALFRAMEWORKOFSTRUCTUREANDREACTIONS TIONS

• Nuclearstructuretowardsthedriplines:phenomenatoexplore&tounderstand

Neutronskins halo,clusters Changeinshellstructure Newmagicnumbers Localproperties(N,Z)

4He 6He

halo

8He 4He

Neutron skin

• 2008:what is known ?

2016:areatoexplore?

Driplines:limit ofnuclear binding,largeisospin Exploration:newexotic structures neutronskin Tests:nuclear modelling &interactionsVNN(Tz) Weaklyboundstates? Continuum ? Isospin dependence?

• Nuclear landscape towards thedriplines
• !

" #$ # #

• #!
• !%

!

• "

%

&'

• "%

##

• (#
• # )
• #*
• (
• Very fewdriplinenuclei havetheir identity card complete

Masses,size,densities,neutronexcitation, lowlying spectroscopy,Shellstructure

6He

Dripline: 8He neutronskin

• Searchforlowlyingresonancesandstudyofneutronexcitations

MUST:Y.Blumenfeld etal.,NIMA421,421(‘99) CATS:S.Ottini etal.,NIMA431,476(‘99).

beam

• (

(p,p p,p’ ’)probe )probe

Particlespectroscopy C.Jouanne,VL.etal.,10,11C(p,p’) PRC,014308(’05) Nucleardensities, neutronexcitation structurestudiesby(p,p’)&(p,d)reactions usingGANIL/SISSIorSPIRALbeams andMUST+CATS Weaklybound nuclei Unbound excited states lowlying resonances Inelastic scattering : sensitivetothe shape ofthedensity Halo,Neutronskinstructure Elastic scattering sensitivetothe matter rms

• $+

+

• rmsm (10C): ± 0.1fm ;rmsm (11C): ± 0.1fm

[rmsm (12C):2.30(3) fm]

• f(
• f(p,p

p,p’ ’)&direct )&directreactions reactions at at low low energy energy: :8

8He(

He(p,p p,p’ ’) )

Collaboration:SPhN,GANIL,IPNOrsay, FLNRDubna,Univ.Ioannina(Greece)

PROBE:8He(p,p’)8He*

MUST

X,Y,T,E

• Si Strips 300m

Si(Li)3mm CsI 1.5cm

• He

SPIRAL

8He

@15.7A.MeV 14000/s [1ary beam:13C @75A.MeV]

CH2 target

Beam detector CATS2

CATS1 testofthevalidityofthedensities eg 6He(p,p’) @40.9MeV/nGANILMUST A.Lagoyannis etal.,PLB!",27(‘01) 2nHalofeatures 6HeNP,49c(‘03)

$+ +

• T1/2 =119ms

neutronskin? Resonances

8He(T1/2=119ms)I=104 /s

reactiontargetCH2

set set up up at at GANIL GANIL

# $ %

• SPIRAL 8He+p@15.7A.MeV

Structureof Structureof8

8He

Heextracted extracted from from direct directreactions reactions onproton

• nprotontarget

target

F.Skaza PhD SPhN F.Skaza,N.Keeley,VLetal., PLB&"'.82(’05) N.Keeley etal., PLB&&,222(’07) Coupledchannel calc.: N.Keeley (SPhN)

8He(p,p)

8He(p,t)6He(0+) 8He(p,t)6He(2+) 8He(p,d)

CRCcalc

Structureofgroundstate&searchforunboundexcitedstates spectroscopyoflightchargedparticlesp,d,t (MUST) measurementsofresonancesinHeNPA788c,260(’07) angulardistributions;analysisin ( ) * PLB&"'.82(’05); &&,222(’07)

• He(p,d)HeCS=4.4± 1.3

[CCBAanalysis] CRC(p,p)(p,d)CS=3.4± 1.3 PLB619.82(’05) (p,t) wavefunctionofHe%&He [8He/6He(0+)]=1; [8He/6He(2+)]=0.014 Configurationmixing: (p3/2)4 and(p3/2)2 (p1/2)2

Structureof Structureof8

8Heextractedfromdirectreactionsonprotontarget

Heextractedfromdirectreactionsonprotontarget

Consistentwith results from quasifreescattering of8He measured at GSI, LVChulkov etal,NP!',43(’05)

+:SPIRALMUST[12] F.Skaza etal.,PRC(’07) N.Keeley etal,PLB&&,222(‘07) CRCCoupledreactionchannelanalysis: N.Keeley (SPhN,Inst.A.Soltan)

CRCcalc

8He(p,t)6He(0+) 8He(p,t)6He2+ 8He(p,d) 8He(p,t)6He(0+) 8He(p,t)6He(2+)

+:A.A.Korsheninnikov etal,PRL',082501(‘03) RIKEN61.3A.MeV CRCcalc

p n 1s1/2 1p3/2 1p1/2 p n 1s1/2 1p3/2 1p1/2

• Alpha+4n

, ) -(

Conclusions

Testofthevalidity of8Hegs densities using (p,p): neutronskinfeaturesclosetoNCSMdensities COSMAnotvalid (p,p’)mainlysensitivetotheneutronexcitation; Transitiondensities2+ 0+ :NCSMcalc.overestimatethep&nexcitations

ρ ,ρ

• .

./ /

• NCSM

2.46 2.59 2.00

NCSM,Navrátil

2.51 2.67 1.95

HF+corr Sagawa

2.52 2.74 1.69

COSMA5body Matter Neutron Proton

Rms (fm)

8He

NCSM(NoCoreShellModel) (V3eff4hw,13MeV)

Testoftransitiondensities ;Analysis inprogress 0. ./ / Coupling Coupling with with the( the(p,t p,t) )

NEUTRON NEUTRON SKINTHICKNESS:~0.6+/ SKINTHICKNESS:~0.6+/ 0.05 0.05fm fm

Validationofnocoreshellmodel calculations(NCSM)forgs COSMA: Alpha+4n

• CEASACLAYDSM/DAPNIA/SPhN :

N.Alamanos,F.Auger,A.Drouart,A.Gillibert,V.Lapoux, L.Nalpas,E.Pollacco,R.Raabe, JL.Sida,F.SKAZA(PhD). IPNOrsay :D.Beaumel,Y.Blumenfeld,F.Delaunay,E.Becheva,JA.Scarpaci Ganil :L.Giot,P.RousselChomaz FLNR Dubna :S.Stepantsov,R.Wolski University ofIoannina :A.Pakou

Participantsoftheexperiment 8He(p,p’)

ANALYSIS:

Microscopic Microscopic densities densities

P.Navrátil +interactionArgonne H.Sagawa HF+correlations Futur:cf M.Ploszajczak Ganil 12 12 3 3 codeDietrich(Livermore);form

form factors factors ( (homemade

homemade,VL)

,VL)

+CRC

CRCcalc.N.KEELEY

With theFresco code(IJThompson,SurreyUniv).

CEADAPNIA,GANIL,IPNOrsay

• DAPNIA SEDI E.Atkin,P.Baron,F.Druillole,F.Lugiez,B.Paul,M.Rouger ;
• SPhN :A.Drouart,A.Gillibert,V.Lapoux,L.Nalpas,E.Pollacco
• IPNOrsay SED:P.Edelbruck,LLavergne,L.Leterrier,A.Richard,M.Vilmay,E.Wanlin,
• StructureY.Blumenfeld,D.Beaumel,E.Becheva
• GANILGIPM.Boujrad,L.Olivier,B.Raine,F.Saillant M.Tripon,Physics P.Roussel Chomaz

• 100mm

MUST1→ MUST2:improvments factor3inactivearea smallervolumeofPAmp :x6 bettertimeresolution

MUr à STrips 2,newgenerationofMUST

Increasedcompacity dueto theASICtechnology (Application Specific Integrated

Circuit)

coïncidences particle γ Si(Li Si(Li) ) 4.5mm 4.5mm CsI CsI 3cm 3cm 4x4 4x4 segments segments Sistrips Sistrips 300 300 m m 100x100mm 100x100mm2

2

X,Y,T,E 128X 128Y

E

• 2004

2004 6 6

Developed by: DAPNIA/SEDI:XelectronicsR&DASIC GANIL IPNOrsay

collaboration:CEADAPNIA, GANIL,IPNOrsay

MEASUREMENTSANDANALYSISOFREACTIONSINCOUPLED CHANNELS

collaborationMUST2: SPIRAL+ Futur SPIRAL2 Evolutionofneutronexcitation

Mn vs N alongisotopicchains

Exoticshapesandresonances Oneparticlestate Spectroscopicfactors

• 45 *

,-.,/ #! 0' ' '

1, '2

• ,'/,

!"##$%

• "--
• MUST2collaboration:

DAPNIA,GANILetIPNOrsay

$- *

3' /$(0 4$4$5

• /5%6715/#$89:%6

;4$ <445=7 1-($$: >45 /(4: <=7 "$0#($: <=7,;#4$: ?3 ;$@''7 ;$4 #4''

• /-
• ?A/?-??(0"%?

• Experimental setup with MUST2

CH2target 1mg/cm2

• SISSISPIRALBeams

8He, 20,22O,14O

I=104 105 /s

p,d,t

Identification A,Z:SPEG MUST2 CATS2

MUST2@d=15cm 525deg lab (1580c.m.) Sect.Eff (p,t) ~5103– 0.5mb/sr

• structureofexoticnucleiviadirectreactions

)1

Beam tracking

ex:SPIRAL2'&Kr@10MeV/nI=104 /s'&Kr(d,p)'Kr,(d,d’)(d,t) 506724) , ..,.Kr,Sn@2050MeV/nI>105 /s

Complete Completekinematical kinematical reconstruction reconstruction access access to tobound bound and andunbound unbound states states 58349 Particlespectroscopy(d,pγ)

• Identification::7

(d,pγ) A+1Z

Chargedparticlespectroscopy Thin target CH2, CD2 1mg/cm2

I(>5.103/s)

(d,pγ γ γ γ)

Gammadetection

;(.";

;

CD2

p Transferreactions ;coupling betwen particle andgammaspectroscopy

• Nuclear landscape towards thedriplines

#! #" $

• !

"

• ($

#"

• %
• #$

# # #! "

structureof 24O?

24O 23N 22C 31F 30,31,32Ne

33Na 34Mg

38Mg

Next driplinenuclei ?

37Na

36 33 39

Tarasov97 Sakurai PLB448,(99) Notani PLB542(02), Lukyanov02 Tarasov PRC75(’07)

43Si 40Mg 44Si

Lowlying resonances ? Neutronskin? Neutronexcitation? Density Profiles? Newshell effects ?

CompletetheIdentity card of driplinenuclei

34Ne

+ +4 4

• Driplinestudies

Driplines :limit ofnuclear binding,largeisospin Exploration:newstructuresofexotic nuclei Tests:nuclear modelling &interactionsVNN(Tz) SIMPLEPROBE:(p,p’)combinedtoCoulex information directreactions ininversekinematics,missing massmethod

Spectroscopy oflowlying resonances,unbound states, neutronexcitation,exoticexcitationmodes softdipoleresonanceandtransitiondensities Halo,skin features ofweaklybound exotic nuclei

ρ ,ρ

localshellchange:likeN=16(34,70..)indicatedby Ex(2+),B(E2)S2n,andevolutionof neutronexcitation

FINDNEWREGIONSOFINTEREST Nuclei with largematter extension(neutronskin,superdeformation…) Newshell gaps

5<5,67,7= thesystematics ofneutronexcitation along isotopic chains 5,Probethestructure&spectroscopy at largeisospin

Measure unbound states

• 5<27067,3

• neutrons

fp sd d5/2 d3/2 s1/2

stability

f7/2 p3/2

sd sd fp fp

$ $

N=16 Z=14

30Si

N=20

" "

N=8

p3/2 p1/2 s1/2 Shelleffects faraway from stability with newgenerations ofRIBs

Localproperties (Z,N) N=34,40,70instead ofN=50,82?

EURISOL

systematics ofneutronexcitationsvsN Search fornewmagic numbers

neutrons fp sd d5/2 d3/2 s1/2

driplineN=16,Z=8,24O

f7/2 p3/2

sdfp N=14

22O

N=16 N=8

#!

N=16 Learnt from 1st generation ofRIBs

(1h11/2)"

ν ν ν ν

82 (f7/2)

• Evolutionofneutronexcitation

Mn vsN along isotopic chains

Exotic shapes andresonances Oneparticle state Spectroscopic factors

Beams Variety A,Z Limit ofnuclear binding,I↑

2012+ 2020+

Alphaclusters states Skinandhalos Softcollectivemodes

• Going closer todriplines with higher intensities :opened physics fields

Far..faraway

Sn

134136Sn 9496Kr 9496Zn 9698Sr

5 3 4 1 2

Unboundstates

MeV

• 50672

5

• 6
• 7

2

Ifthebeams arenew(36Ne?6068Ca?)

• rrareat present (24Ofew/sat GANIL,RIKEN)

with EURISOL:counting ratesless oraround 103105 /s

* $>( * * 4) > -* * ) (4 *

Which Which beams beams ? ?We We want want togainin togaininexoticity exoticity

Completethe(p,p’)chains O(24O),Ne+Mg,Si,S,Ar +spectroscopy ofneutronrich nuclei: around doubly magic Z=28,N=40,50;Z=50,N=82 around ,?.,?**> -.,?!.,?

58- * 3, ., $>(.

&4." ;?.,?

• Evolutionoftheneutronskinthickness:exofNeonisotopes

Density functional.calc.with R.Lombard’s code Similar trendinHFBdef (Sly4)calc of JDobaczewski,M.V.Stoitsov,etal., PRC&,054312(‘03)

• NeutronskinstructureofNeviadirectreactions onprotontarget

34Ne+p p’ +34Ne* p +32Ne+2n

p’ + 34Ne* p +30Ne+4n

34Ne(p,p’)34Ne*

$

• !

(

($ (

AB N

31,33Neunbound

Sn 0+ 2+

,

S2n 1.63MeV 1.97 S2n 0+ 2+

,

Sn 300keV 947

• NeutronskinstructureofNeviadirectreactions onprotontarget

34Ne+p p’ +34Ne* p +32Ne+2n

p’ + 34Ne* p +30Ne+4n

34Ne(p,p’)34Ne*

34Ne+p

t +32Ne

• t+32Ne*

t +31Ne*+n t +30Ne+2n

34Ne(p,t)32Ne

34Ne+p d+33Neunbound d +32Ne+n

d+ 33Ne* d +30Ne+3n

34Ne(p,d)33Ne

34Ne+p

α α α α +31F

34Ne(p,alpha)31F

Q(p,alpha)=1.696#MeV[ame03] Q(p,d)=1.27#MeV[ame03] Q(p,t)=8.18#MeV[ame03] Allreactions tobe considered intheCoupledReaction channel scheme: Phasespace background duetoneutrons produced by decaying unbound states Low Sn,S2n,S4n,… 526506,@ , ( (

• $8 )

) ) * ) lightrecoilinaparticledetector incoincidencewithAZID of forward focused heavy fragments inspectrometer +additional neutrondetection 6+.5#*) $2

• NeutronskinstructureofNeviadirectreactions onprotontarget

34Ne+p@25A.MeV

• (

( ) ) (p,p’)34Ne

gs,Eexc=2,3and5MeV

(p. )32Ne

gs,Eexc=1and2MeV

(p.( ()33Ne

unbound Gs and Eexc at 2MeV

(p.) ))31Fgs

> -

• Improved detection forEURISOLexperiments

Steps beyond inthedetection :

ASICtechnology (ApplicationSpecific Integrated Circuit)

(compacity ofalldevices)

Mixeddetection

(gamma+charged particles +… neutrons): Ex:Ge+Si+scintillator inacrystalGeSiball array

Higher multiplicities inLCParrays (3,4,..)

challengesinacquisitionsystems :

synchronize separated arrays &triggers needs toreduce dead time

A,ZID ofheavy fragment

inaspectrometer

• rSiLiCsI array

NEUTRONDETECTION

Charged Charged Particlespectroscopy Particlespectroscopy neededtoexplore unboundstates Thinlighttargetsp,d

• E~400keVto1MeV
• (p,p’),(p,d)(p,t)

+

Inversekinematics : goodEnergy resolution inEexc requires :beam profileontarget

• beam

beam tracking tracking detectors detectors

• Gamma

Gamma rayspectroscopy rayspectroscopy

• neededtoseparate

neededtoseparate closeexcitedstates closeexcitedstates ThicktargetE~20keV (d,p)@9MeV/n

2016Wishes forCoupled Detection devices

• CRCcalculations,CDCC

Cf NickKeeley JOLIOTCURIE‘07 DOTHEBESTPOSSIBLECALCULATIONS!!!! DOTHEBESTPOSSIBLECALCULATIONS!!!! DWBAis alimited framework,turns outtobe WRONG forstronglycoupled channels

ANALYSISOF(D,P)CROSSSECTIONS...

Successful analysis forthestable nuclei [cf 40Ca(d,p)]:E=7,8,9,10,11,12MeV Lee,..Schiffer,Satchler,Drisko,PR 1364B(’64) 40Ca(d,p)41Caatestofthevalidity oftheDWBA

Satchler Directnuclear reactions, Clarendon Press,OxfordUniv Press 1983

Weknowthataverageproperties&parameterizationsareworkingforstablebeams(~300species) ONLYSMALLPARTofall2000RIB,evenmore3000possibleones… Ex:N.Timofeyuk &RCJohnson,PRC59,1545(‘ 99):dbreakupincluded within theadiabatic approach from Johnson&Soper

Analysis ofthe16O(d,p)17O,10Be(d,p)11Be,and11Be(p,d)10Bereactions.

• ) *# ** - )( $((.)* * Atestcalc.:12C(d,p)@25MeV

10Be(d,p)@12and25MeV,N.Keeley,*N.Alamanos,andV.L,0&'.&&B

« TheDWBAwas shown tobe inappropriate fortheanalysis of(d,p)reactions some 30years ago,duetotheimportanceofthedeuteron breakup channel. » MEASUREELASTICSCATTERING toestimate coupling effects (virtual coupling potential related toexcited states,compoundnucleuseffects… needed forcoupling scheme … MEASUREINELASTICSCATTERING(d,d ’)(p,p ’)

• EURISOL:anewtheoreticalframework

Probeforthestructure:(p,p’) Butfluxsharedbetweenseveralreactionchannels elasticandtransferreactions +competitionbetweenmainreactionchannels NEEDTODEFINETHEAPPROPRIATESCATTERINGTHEORY Stateoftheart: Coupledreactionchannelanalysis explicitchannel coupling +Microscopicpotentials

=053 ( ) *- $

• (# (-
• 5*3 7 ( .
• Checkroleofcontinuumcoupling
• Sensitivitytothedetailedstructureofexoticnuclei,
• Testunusualshape+unboundstates
• Comparetomodels(SM,HFB,BCS+QRPA,AMD)

• EURISOL:anewtheoreticalframework

Data+Virtualcouplingpotential forelastic scatteringof10,11Beonp V.Letal., PLB&!,198(’08) Strongpickupcouplingeffect

• np+11Beelasticscattering

N.Keeley andV.LPRC,014605 (‘08) CRCcalc :11Be(p,d)10Be*pickuptothe5.960MeV 1 and6.263MeV 2 doubletofexcitedstatesin10Be

• spectroscopyoflow

spectroscopyoflow lyingstatesofneutron lyingstatesofneutron richisotopesvia( richisotopesvia(p,p p,p’ ’),( ),(p,d p,d)( )(p,t p,t),( ),(d,p d,p) )

Measurementtounboundstates: Particlespectroscopy Largeenough * * * * 50672 50672 Largeangularcoverage allreactionsmeasuredsimultaneously Elasticandtransfer Lowparticlethreshold:smallc.m.angles

• Possibleto carryout

fullcoupledreactionchannelanalysis EXTRACTformfactorsfrom(p,p’) spectroscopicfactorsfrom(d,p) suitable rangeofbeam energies for(p,p’)and(d,p) :E~1030MeV/n

In2016+:newbeamsofneutronrichNe,Ca,Ni,Kr,Sn isotopes… Accesstoneutronthicknessevolution+changeinshellstructure

Present(1st generation)intensities:fewpart/s Needed:(atleast)"4"! C*

34Ne+p@25A.MeV

• (

( α α α α α α α α 40c.m. 20c.m. 10c.m. Improvment ofexp setup +Theoretical framework

• vlapoux@cea.fr

Theoreticalframeworkfortheanalysisofdirectreactions

Enhancedeffectsinthecaseofweaklyboundexoticnuclei

Couplingtocontinuum,3bodymanybodycorrelations Shellstructureembeddedinthecontinuum

• * ) (*$-# (* ) *( *

* ) (*$-# (* ) *( * 9 9 theseeffectsandtheisospindependenceofthenuclearinteraction PROTOTYPESTUDY:8He(p,p’)&(p,d):PLB&"',82(’05) Usualframework:DWBA,notvalid,needtooperatewithCRC Theusualingredientsandmodelsbasedonpaststudiesforstablenuclei mustbeputintoquestionAPRIORI

Howgood(potential,framework)isreallygoodforexoticbeams Howgood(potential,framework)isreallygoodforexoticbeams? ? Validityofopticalpotentials? Validityofopticalpotentials?

Examinetheassumptionsinthecaseofweaklyboundnucleiorforspecificcoupling(large spectrosocpic factors,enhancedexcitationetc..) Tobecheckedbymeasuring carefully theelasticscattering , TESTINGGROUNDFORTHEINTERACTIONPOTENTIALANDTHEREACTIONMODEL FORMALISMinCOUPLED FORMALISMinCOUPLED REACTIONCHANNELS REACTIONCHANNELS Toincludethecouplingtoexcitations ANDto ) * COMPLEXMICROSCOPICPOTENTIALS COMPLEXMICROSCOPICPOTENTIALS totestthevalidityofnucleardensity

Improvedapproach(bestwecandotoday)