CONTINUUM STATES OF LIGHT NEUTRON-RICH NUCLEI VIA
TRANSFER & KNOCKOUT…
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
NIGEL ORR *
[5H & 13Be via proton removal ]
* T AL KALANEE, J GIBELIN, H AL FALOU + CHARISSA+DEMON + MUST COLLABORATIONS
‟Formless Continuum” – Jack Haas
… toujours la même chose
avec lui … mieux vaut peut-être
rester ici avec mon
ballon de rouge
THE LIGHT NEUTRON-RICH NUCLEI …
10Li
9He
… driplines and beyond experimentally accessible via
knockout/breakup
neutron transfer
... nuclear structure theory becoming mature (NCSM, ab initio, …)
N=7 : STRUCTURAL EVOLUTION WITH ISOSPIN* …
… 9He ??
1/2+ - 1/2- level inversion …
* Also input for 3-body models of 10He, …
T Otsuka et al. PRL 2001
PG Hansen et al.
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
Si strip
(d,p)
tracking
“knockout”
n
beam
PID + EB
CD2 or Be / C
heavy beam-like
residue
(PID, E, q, f)
… INVERSE KINEMATICS
8He(d,p)
SINGLE-NEUTRON TRANSFER
…
d+Ap+B
n
p
d=p+n
d
1d5/2
B=A+n
1p1/2
2s1/2
p
A
A
n
B
1p3/2
N=6
1s1/2
neutrons
+
8He
p
gs J = 0
 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 8He “2p-2h”)*
gs
* 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 …
Er=180±85 (G=180±160) ; 1240±120 (G=130+170/-130) ; 3420±780 (G=2900±400) keV
T Al Kalanee, J Gibelin et al. [MUST2], PRC88 2013
d(8He,p)AHe @ 15 MEV/NUCLEON …
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
DWBA & CCBA – N Keeley
T Al Kalanee, J Gibelin et al., PRC88 2013
d(8He,p)AHe @ 15 MEV/NUCLEON …
‡
*
[ Gsp (ℓ=0)  2700 keV]
†
**
[ Gsp (ℓ=1)  2400 keV]
†
[ Gsp (ℓ=2)  3000 keV]
‡ a ~ -12 fm
s
DWBA: * No reliable form factor for ℓ=0 using WBEA
† Uncertainty dominated by form factor
** Barker (2004) R-Matrix < 0.1
T Al Kalanee, J Gibelin et al., PRC88 2013
KNOCKOUT & BREAKUP …
… nucleon removal via “knockout” or breakup of projectile
(b  0.3) with known structure + in-flight decay
 fragment – n FSI
Vf
Proj.
Vf - Vn
target
AZ
 A-1Z + n
Vn
Ed 
1



 2
μ Vf Vn
2
APPROX. “SELECTION RULES” …
(i) 1 & 2-proton knockout  Dℓn0 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 …
… 10Li *
s1/2 - p1/2 level inversion
* pp
…
s1/2 ;p3/2  2-,1- ; 2+,1+
1/2 
Brida e at al.,. NUPA (2006)
PG Hansen et al.
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]
[ Decay of 11Li* & 12Li … ? ]
+ background
H Al Falou et al.
9He:
C(11Be,8He+n) @ 35 MEV/NUCLEON
s-wave [as = -3 ~ 0 fm (3s)]
[-2p]
+ 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]
[ Decay of 10He … ? ]
GSI-LAND : HT Johansson, Yu. Aksyutina et al. (2010)
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 …
CCBA
CCBA – Antonio Moro
TB Jeppesen et al. [ISOLDE], PLB642 2006
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 …
SPECTROSCOPY OF 18B :
THESHOLD S-WAVE STRENGTH
…
… PRELIMINARY
Lebond, Ogoshi, et al., LPC-TITECH-SAMURAI: NP1106 – SAMURAI04 @ RIBF
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
EXPERIMENTAL RESPONSE FUNCTION …
Resolution
FWHM ~ 0.3 Ed1/2
Efficiency
en
FWHM Ed
 model distributions must be “filtered” through the simulation
JL Lecouey LPCC 04-03
INITIAL STATE DEPENDENCE OF UNBOUND STATES …
• sudden approximation
 neutron configuration of projectile preserved (Dℓn = 0)

a(k) r2drk*(r)y 0(r)
0
Final unbound state
Initial bound state
  fragment j
y 0  A1  j
Decay
Energy
ds  Ed a(k)
dEd
2
Simulation
Comparison to
data
(c2)
G Bertsch et al., PRC (1998), L Chen et al. PLB (2001)
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 …
13Be:
DISCUSSION …
Single-Neutron Removal in the p-sd shell : AZ  A-1Z
s1/2 intruder (halo)
p-shell
sd-shell
Inclusive Expt : E Sauvan, et al., PLB (2000)
13Be:
DISCUSSION …
13Be:
DISCUSSION …
Randisi et al.
p,C(14Be,12Be+n)
vs
C(14B,12Be+n)
13Be:
UNMIXED SHELL MODEL (WBT/P)
…
[HMI/Dubna]
DJ Millener, unpublished
13Be:
C(14B,12Be+n) VS MIXED (0–3)ħw
SHELL MODEL
*
* WBP & HTF predictions: 1/2+ normalised to 0.40 MeV level in EXPeriment
…
*
G Randisi et al.
13Be:
C(14B,12Be+n) …
G Randisi et al.
13Be:
C(14B,12Be+n) …
… virtual vs resonant s-wave strength + d-wave resonance
G Randisi et al.
13Be:
C(14B,12Be+n) …
G Randisi et al.
13Be:
C(14B,12Be+g) …
… 12Be*: Ex (2+) =2.1 MeV ; Ex (1-) =2.7 MeV ; Ex (0+) =2.25 MeV
G Randisi et al.