Collaboration LPC-CHARISSA-DEMONCollaboration LPC-CHARISSA-DEMON

H Al Falou, FM Marqués, JL Lecouey, H Al Falou, FM Marqués, JL Lecouey, NA OrrNA Orr, …, …

Spectroscopy Beyond the Neutron Dripline: Spectroscopy Beyond the Neutron Dripline: 99He He && 1010LiLi

““I have come 500 miles just to see a halo …I have come 500 miles just to see a halo …””

Who wrote and sang …Who wrote and sang …

MotivationMotivation

Experimental Experimental ApproachApproach

Selection “Rules”Selection “Rules”

BackgroundsBackgrounds

N=7 : N=7 : 1010Li & Li & 99HeHe

ConclusionsConclusions

Spectroscopy Beyond the Neutron Dripline: Spectroscopy Beyond the Neutron Dripline: 99He & He & 1010LiLi

The Light Neutron-Rich Nuclei …The Light Neutron-Rich Nuclei …

10Li

Structure =core+xnStructure =core+xn

… … driplines and beyond experimentally accessible, extreme test of models driplines and beyond experimentally accessible, extreme test of models

(shell model, shell model in continuum, (shell model, shell model in continuum, ““ab initioab initio””, cluster, etc), cluster, etc)

9He

Light Unbound Neutron-Rich SystemsLight Unbound Neutron-Rich Systems

• input for 3-body modelsinput for 3-body models

3-body systems 3-body systems n-n and core-n interactions n-n and core-n interactions

1111Li : Li : 9 9Li-n interaction Li-n interaction spectroscopy of spectroscopy of 1010LiLi

1010He : He : 88He-n interaction He-n interaction spectroscopy of spectroscopy of 99HeHe

N=7 1/2N=7 1/2++ – 1/2 – 1/2-- Level Inversion … Level Inversion …

PG Hansen et al.PG Hansen et al.

… … 1010Li Li && 99He ??He ??

Experimental ApproachExperimental Approach

… … ““knockoutknockout”” or breakup + inflight decay or breakup + inflight decayprojectile structure knownprojectile structure known

Vf

Vn

Vf-Vn

2nf VV21

dE

targettarget

Proj.

AZ A-1Z + n

DEMONDEMON

90 modules (90 modules (NE213NE213) )

ToF ToF && position position

nn ~ 10% ~ 10%

Kinematically “CompleteKinematically “Complete”” Measurement Measurement

dEFWHM

ResolutionResolutionExperimental Response FunctionExperimental Response Function

EfficiencyEfficiency

FWHM ~ 0.3 EFWHM ~ 0.3 Edd1/21/2

nn

JL Lecouey LPCC 04-03JL Lecouey LPCC 04-03

model distributions model distributions mustmust be be ““filteredfiltered”” through the simulation through the simulation

Selection Selection ““RulesRules” - ” - Sudden ApproximationSudden Approximation

(i)(i) 1 1 && 2-proton knockout 2-proton knockout llnn=0 proj. valence neutron config.=0 proj. valence neutron config.

C(C(1111Be,Be,1010Li)X ,C(Li)X ,C(1111Be,Be,99He)XHe)X ss1/2 1/2 [ [ 1111Be CBe C22S (S (ss1/21/2)) 0.8 ] 0.8 ]

(ii)(ii) fragmentation (-xp,-xn) fragmentation (-xp,-xn) valence neutron config. + others valence neutron config. + others

C(C(1414B,B,1010Li)X , C(Li)X , C(1414B,B,99He)X He)X ss1/21/2 + + pp1/21/2 + … + …

C( C(1212Be,Be,99He)X He)X ss1/21/2 + + pp1/21/2 + + dd5/25/2 + … + …

NB:NB: E Edd lineshape dependent on initial statelineshape dependent on initial state (esp. for broad final states) (esp. for broad final states)

““backgroundbackground” ≡” ≡ non-resonant continuum non-resonant continuum event-mixed distribution * event-mixed distribution *

* ie., * ie., uncorrelateduncorrelated fragment-neutron pairs fragment-neutron pairs

EErr = 85 = 85 15 keV 15 keV

sp sp << 100 keV << 100 keV

uncorrelated uncorrelated 1515B+n distributionB+n distribution

BACKGROUNDBACKGROUND: C(: C(1717C,C,1515B+n)X – B+n)X – single-proton knockoutsingle-proton knockout

JL Lecouey et al, nucl-ex/0802.4225JL Lecouey et al, nucl-ex/0802.4225

““backgroundbackground”” ≡≡ neutrons evaporated from PLF + continuum neutrons evaporated from PLF + continuum

BACKGROUNDBACKGROUND : C( : C(1414B,B,66He+n)X – He+n)X – fragmentationfragmentation

JL Lecouey, LPCC T 04-03.JL Lecouey, LPCC T 04-03.

Scattering/Virtual s-wave StatesScattering/Virtual s-wave States

aass = 0 fm no FSI ; a = 0 fm no FSI ; ass << 0 fm stronger FSI << 0 fm stronger FSI

1010Li : Low-Lying Level Scheme Li : Low-Lying Level Scheme **

* * ““PartialPartial”” – also d( – also d(99Li,p) etcLi,p) etc s-s-virtual virtual E Er r ~~ ћћ2 2 / 2a/ 2ass

1010Li : C(Li : C(1111Be,Be,99Li+n) Li+n) @@ 35 35 MeV/nucleonMeV/nucleon

H Al Falou LPCC 07-03H Al Falou LPCC 07-03

uncorrelated / event-mixed distribution uncorrelated / event-mixed distribution **

** normalised for comparison at high E normalised for comparison at high Edd

1010Li : C(Li : C(1111Be,Be,99Li+n) Li+n) @@ 35 35 MeV/nucleonMeV/nucleon

s-wave [as-wave [ass = -14 = -14±±2 fm] + non-resonant continuum2 fm] + non-resonant continuum

H Al Falou LPCC 07-03H Al Falou LPCC 07-03

1010Li : C(Li : C(1414B,B,99Li+n) Li+n) @@ 35 35 MeV/nucleonMeV/nucleon

s-wave virtual state + p-wave [Es-wave virtual state + p-wave [Er r = 0.51, = 0.51, = 0.50 MeV] + background= 0.50 MeV] + background

H Al Falou LPCC 07-03H Al Falou LPCC 07-03

99He : He : Low-Lying Level Scheme Low-Lying Level Scheme **

** 99Li IAS expts not shown ; Li IAS expts not shown ; [Set87, Boh88, Oer95][Set87, Boh88, Oer95] assignments tentative assignments tentative

99He : C(He : C(1111Be,Be,88He+n) He+n) @@ 35 35 MeV/nucleonMeV/nucleon

uncorrelated distribution/event mixed distributionuncorrelated distribution/event mixed distribution

H Al Falou LPCC 07-03H Al Falou LPCC 07-03

99He : C(He : C(1111Be,Be,88He+n) He+n) @@ 35 35 MeV/nucleonMeV/nucleon

s-wave [as-wave [ass = -3 ~ 0 fm (3 = -3 ~ 0 fm (3)] + non-resonant continuum)] + non-resonant continuum

H Al Falou LPCC 07-03H Al Falou LPCC 07-03

99He : C(He : C(1414B,B,88He+n) He+n) @@ 35 35 MeV/nucleonMeV/nucleon

uncorrelated distribution/event mixed distributionuncorrelated distribution/event mixed distribution

H Al Falou LPCC 07-03H Al Falou LPCC 07-03

99He : C(He : C(1414B,B,88He+n) He+n) @@ 35 35 MeV/nucleonMeV/nucleon

s-wave [as-wave [ass = -3 ~ 0 fm] + p-wave [E = -3 ~ 0 fm] + p-wave [Err = 1.2, = 1.2, = 1.0 MeV] + background= 1.0 MeV] + background

H Al Falou LPCC 07-03H Al Falou LPCC 07-03

99He : C(He : C(1212Be,Be,88He+n) He+n) @@ 41 41 MeV/nucleonMeV/nucleon

s-wave [as-wave [ass = -10 fm] + p = -10 fm] + p1/21/2 [E [Err = 1.2 MeV] + (d = 1.2 MeV] + (d5/25/2) [E) [Err = 2.4 MeV] + background = 2.4 MeV] + background

G Normand LPCC 04-03G Normand LPCC 04-03

Conclusions Conclusions && Perspectives Perspectives • spectroscopy beyond the dripline using breakup/knockout of RNB …spectroscopy beyond the dripline using breakup/knockout of RNB …

1010Li : Li : low-lying s-wave strength (alow-lying s-wave strength (as s = -14= -14±2±2 fm) fm)

low-lying p-wave resonance (E low-lying p-wave resonance (Err = 0.5 MeV) = 0.5 MeV)

N= 7 inversion confirmedN= 7 inversion confirmed

[ [ but … but … pp3/23/2ss1/2 1/2 ,,pp1/2 1/2 ,,dd5/25/2]]

99He : He : low-lying s-wave strength (alow-lying s-wave strength (as s 0 fm) + E 0 fm) + Exx1.2 & 2.4 MeV1.2 & 2.4 MeV

(l>0) (l>0) N= 7 inversion … ??N= 7 inversion … ??

[ [ FSI << FSI << 99Li+n ??Li+n ?? ] ] validity of s-wave virtual states (eg., deformed validity of s-wave virtual states (eg., deformed 99Li core) ??Li core) ??

more realistic more realistic structurestructure + + reaction modellingreaction modelling needed … needed … … including non-resonant continuum + other backgrounds … including non-resonant continuum + other backgrounds