CONTINUUM STATES OF LIGHT NEUTRON-RICH NUCLEI VIA TRANSFER & KNOCKOUT…

‟Formless Continuum” – Jack Haas

Example : N=7 structure - 9He, 10Li …

… via single-neutron transfer on 8He [9Li]

versus

… nucleon knockout & fragmentation of fast secondary beams

GOAL: Compare and contrast

… Open issues and questions

[5H & 13Be via proton removal ]

NIGEL ORR *

* T AL KALANEE, J GIBELIN, H AL FALOU + CHARISSA+DEMON + MUST COLLABORATIONS

… toujours la même chose avec lui … mieux vaut peut-être rester ici avec monballon de rouge

THE LIGHT NEUTRON-RICH NUCLEI …

10Li

… driplines and beyond experimentally accessible via knockout/breakup neutron transfer

9He

... nuclear structure theory becoming mature (NCSM, ab initio, …)

N=7 : STRUCTURAL EVOLUTION WITH ISOSPIN* …

T O

tsuk

a et

al.

PR

L 20

01

… 9He ??

PG Hansen et al.

1/2+ - 1/2- level inversion …

* Also input for 3-body models of 10He, …

HISTORICAL INTERLUDE…

… some cases accessible via heavy-ion multi-nucleon transfer & double-charge exchange from stable targets/beams

→ complex mechanisms, selectivity (ℓ>>0), complex spectra, …

HMI group, circa 1994

TWO ROADS TO THE CONTINUUM: NEUTRON TRANSFER & FAST BEAM KNOCKOUT/BREAKUP

… INVERSE KINEMATICS

--------

- --------

- --------

- --------

- --------

-

n

(d,p)

Si strip

beam PID + EB

tracking

heavy beam-like residue

(PID, E, q, f)

CD2 or Be / C

“knockout”

8He(d,p) SINGLE-NEUTRON TRANSFER …

1s1/2

1p3/2

1p1/2

2s1/2

1d5/2

N=6

Proton energy and angle Ex of recoil B

Proton angular distribution, ds/dW

angular momentum transfered by neutron, ℓn

ds/dW (expt) = S ds/dW (reaction theory)

8He(d,p)9He Jp = 1/2+ 1/2-, 5/2+, 3/2-(iff 8Hegs “2p-2h”)*

p p

A AB

d

d + A p + B

n

n

d=p+n B=A+n

neutrons 8Hegs Jp = 0+

* 8He(p,d) S(p3/2) 4… 8He(p,t) 2p-2h … MUST [PRC2006, PLB2007 ]

9He: SHELL MODEL (p-sd 0 –1ħw) …

L Chen et al. PLB (2001)

d(8He,p)AHe @ 15 MEV/NUCLEON …

T Al Kalanee, J Gibelin et al. [MUST2], PRC88 2013

Er=180±85 (G=180±160) ; 1240±120 (G=130+170/-130) ; 3420±780 (G=2900±400) keV

d(8He,p)AHe @ 15 MEV/NUCLEON …

T Al Kalanee, J Gibelin et al., PRC88 2013DWBA & CCBA – N Keeley

DWBA Optical Pot’ls: d+8He global parameters Daehnick et al p+9He systematics Koning+Delaroche Form Factors: Woods-Saxon with “Weak Binding” approx CCBA : d breakup only - d+8He CDCC

d(8He,p)AHe @ 15 MEV/NUCLEON …

T Al Kalanee, J Gibelin et al., PRC88 2013

[ Gsp (ℓ=0) 2700 keV]

[ Gsp (ℓ=1) 2400 keV]

[ Gsp (ℓ=2) 3000 keV]

DWBA: * No reliable form factor for ℓ=0 using WBEA † Uncertainty dominated by form factor ** Barker (2004) R-Matrix < 0.1

*

†

†

‡

‡ as ~ -12 fm

**

KNOCKOUT & BREAKUP …

… nucleon removal via “knockout” or breakup of projectile (b 0.3) with known structure + in-flight decay

fragment – n FSI

Vf

Vn

Vf - Vn

2nVfVμ21

dE

targetProj.

AZ A-1Z + n

APPROX. “SELECTION RULES” …

(i) 1 & 2-proton knockout Dℓn0 proj. valence neutron config.

C(11Be,9Li+n)X ,C(11Be,8He+n)X s1/2 [ 11Be C2S (s1/2) 0.8 ]

well adapted to probing low-lying (s-wave strength)

(ii) fragmentation (-xp,-yn) population via neutron-decay of N+1,2, … systems following proton removal

C(14B,9Li+n)X , C(14B,8He+n)X , C(11Li,8He+n)X , s1/2 + p1/2 + …

CAVEAT: decay of narrow resonances in N+1,2,… systems

N=7 : STRUCTURAL EVOLUTION WITH ISOSPIN …

Brid

a e

at a

l.,. N

UPA

(200

6)

… 10Li *

PG Hansen et al.

s1/2 - p1/2 level inversion …

* pp1/2 s1/2 ;p3/2 2-,1- ; 2+,1+

SCATTERING/VIRTUAL S-WAVE STATES …

as = 0 fm no FSI ; as << 0 fm stronger FSI

NB: final lineshape Ed(frag+n) depends on projectile and reaction + decay path

10Li: C(11Be,9Li+n) @ 35 MEV/NUCLEON [-1p]

s-wave [as = -17±2 fm] + non-resonant continuum

H Al Falou et al.

10Li: C(14B,9Li+n) @ 35 MEV/NUCLEON [-2p,-2n]

s-wave [as = -10±2 fm] + p-wave [Er = 0.50, G0 0.50 MeV] + background

[ Decay of 11Li* & 12Li … ? ] H Al Falou et al.

9He: C(11Be,8He+n) @ 35 MEV/NUCLEON [-2p]

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

H Al Falou et al.

9He: C(14B,8He+n) @ 35 MEV/NUCLEON [-3p,-2n]

s-wave [as = -3 ~ 0 fm] + p-wave [Er = 1.2, G0 1.0 MeV] + background

[ Decay of 10He & 11He … ? ] H Al Falou et al.

9He: p(11Li,8He+n) @ 280 MEV/NUCLEON [-1p-1n]

GSI-LAND : HT Johansson, Yu. Aksyutina et al. (2010)[ Decay of 10He … ? ]

9He: “COMPARE & CONTRAST” …

C(11Be,8He+n)Threshold ℓ=0 strength dominates

… as -3 fm

d(8He,p)

ℓ=0 very low yield … as ~ -12 fm [?]

Can lower EB to improve matching (but … )

d(9Li,p) @ 2.36 MEV/NUCLEON …

TB Jeppesen et al. [ISOLDE], PLB642 2006CCBA – Antonio Moro

CCBA

9He : d(8He,p) @ 25 MeV/nucleon

MS Golovkov et al., PRC76 (2007)

→

9He: AB INITIO THEORY …

P Navratil – ECT* Nov 2013

(SOME) OPEN ISSUES …

TRANSFERT:

• How best to model transfer to continuum states ? … what is the best means to treat (s-wave) form factor ??

• Realistic estimates of Gsp to derive C2S ? Standard WS ? … ??

KNOCKOUT/BREAKUP:

• Proper reaction theory to continuum states (very crude at present)

• Need to treat consistently “background” (core recoil, valence-n scattering, non-resonant continuum) in theory

IDEALLY (TRANSFERT & KNOCKOUT):

• “Ab initio” yi & yf combined with realistic reaction theory …

Lebond, Ogoshi, et al., LPC-TITECH-SAMURAI: NP1106 – SAMURAI04 @ RIBF

SPECTROSCOPY OF 18B : THESHOLD S-WAVE STRENGTH …

… PRELIMINARY

HISTORICAL INTERLUDE…

… some cases accessible via heavy-ion multi-nucleon transfer & double-charge exchange from stable targets/beams

→ complex mechanisms, selectivity (ℓ>>0), complex spectra, …

9He : d(8He,p) @ 15 MeV/nucleon

S Fortier et al., AIP Conf Proc 912 (2007)

d(8He,p)AHe @ 15 MEV/NUCLEON …

T Al Kalanee, J Gibelin et al. [MUST2], PRC88 2013

17O : d(16O,p) @ 15 MEV/NUCLEON …

T Al Kalanee, J Gibelin et al., PRC88 2013

d(160/8He,p)17O/9He @ 15 MEV/NUCLEON : RESOLUTION…

T Al Kalanee, PhD Thesis LPC-Caen (2010)

9He: SUMMARY …

T Al Kalanee, J Gibelin et al., PRC88 2013

9He: AB INITIO THEORY …

P Navratil – ECT* Nov 2013

INVARIANT MASS SPECTROSCOPY: LIGHT NUCLEI @ ~40 MeV/u …

9Li+n 12Be+n

dEFWHM

ResolutionEXPERIMENTAL RESPONSE FUNCTION …

Efficiency

FWHM ~ 0.3 Ed1/2

en

JL Lecouey LPCC 04-03

model distributions must be “filtered” through the simulation

INITIAL STATE DEPENDENCE OF UNBOUND STATES …

G Bertsch et al., PRC (1998), L Chen et al. PLB (2001)

• sudden approximation

neutron configuration of projectile preserved (Dℓn = 0)

0

0*2 )()()( rrdrrka k y

Initial bound state

jy 1A0

Final unbound state

jfragment

2)(kaEdEd d

ds

DecayEnergy

SimulationComparison to

data (c2)

INITIAL STATE DEPENDENCE OF VIRTUAL S-STATES …

as = 0 fm no FSI ; as << 0 fm stronger FSI

H Al Falou LPCC 07-03

13Be: DISCUSSION …

s1/2 intruder (halo)

p-shell sd-shell

Single-Neutron Removal in the p-sd shell : AZ A-1Z

Inclusive Expt : E Sauvan, et al., PLB (2000)

13Be: DISCUSSION …

13Be: DISCUSSION …

13Be: DISCUSSION …

p,C(14Be,12Be+n) vs C(14B,12Be+n)

Randisi et al.

13Be: UNMIXED SHELL MODEL (WBT/P) …

DJ Millener, unpublished

[HMI/Dubna]

13Be: C(14B,12Be+n) VS MIXED (0–3)ħw SHELL MODEL …

G Randisi et al.* WBP & HTF predictions: 1/2+ normalised to 0.40 MeV level in EXPeriment

* *

13Be: C(14B,12Be+n) …

G Randisi et al.

13Be: C(14B,12Be+n) …

G Randisi et al.

… virtual vs resonant s-wave strength + d-wave resonance

13Be: C(14B,12Be+n) …

G Randisi et al.

13Be: C(14B,12Be+g) …

G Randisi et al.

… 12Be*: Ex (2+) =2.1 MeV ; Ex (1-) =2.7 MeV ; Ex (0+) =2.25 MeV