Sandrine Courtin Atelier de lESNT Saclay, Feb. 4-6 / 2008 Captures and Molecules Sandrine Courtin Institut Pluridisciplinaire Hubert Curien, Dpartement

Sandrine Courtin Atelier de l’ESNT Saclay, Feb. 4-6 / 2008

Captures and Molecules …

Sandrine Courtin

Institut Pluridisciplinaire Hubert Curien, Département des Recherches Subatomiquesand Université Strasbourg I

http://www-ulp.u-strasbg.fr/


88 20

20

28

28

50

50

82

82

126

-9.32

11.8 Now

N-rich around N = 20 – 28

How ? Transfer reactions transfer process / nucleon-nucleon spectroscopy

Ex : 40Ar (ELab = 255 MeV) + 208Pb (11/2007) n-rich ArWhere ? Legnaro (Prisma-Clara), GANILCollaboration : IPHC, Univ. Zagreb (S. Szilner et al.), Univ. Torino, LNL Legnaro (L. Corradi et al.), Univ. of West Scotland (R. Chapman et al.)

Theory : G. Pollarolo (Univ. Torino), E. Caurier, F. Nowacki (IPHC)

AM

E03-

LMD

, P

. Van

Isac

ker e

t A.E

.L. D

iepe

rink,

In

t. J

Mod

. Phy

s. E

15,1

371(

2006

)



Clustering in light heavy-ions

How ? Narrow ‘molecular’ resonances, fragment, particle, decay Ex : (24Mg-24Mg) resonances in 48Cr

(12C - 12C) resonances in 24Mg (12C - 16O) resonances in 28Si

Where ? Legnaro (Prisma-Clara), Berkeley (Gammasphere), Triumf (Dragon + BGO), Argonne (Gammasphere+FMA)

Collaboration : IPHC, Univ. York (D. Jenkins et al.), Triumf (D. Hutcheon et al.) ANL (C. Lister et al.), Univ. of West Scotland (R. Chapman et al.)

Theory : J. Dudek (IPHC), K. Pomorski (Lublin) LSD Model S. Ohkubo. K. Yamashita (Univ. Kochi) CM D. Baye and P. Descouvemont (ULB) GCM J. Cseh and G. Lévaì (Atomki, Debrecen) ACM

(12C - 12C) resonances in 24Mg (12C - 16O) resonances in 28Si

Molecules Deformation -decay Radiative Capture Reactions : recent results

Now



12C(12C,)24Mg and 12C(16O,)28SiSetting the stage

Resonances ? NOC (F. Haas and Y. Abe, Phys. Rev. Lett. 46 (1981) 1667)

Radiative Capture : Light Particles vs Heavy-Ions

Light heavy-ions : 12C+12C 24Mg, 12C+16O 28Si Sandorfi et al. (BNL, ~ 1980) Narrow resonances @ Bc

No recoil, decay to g.s.

Narrow Resonances (150 keV), Et ~ h molecules



Results on 12C(12C,)24Mg and 12C(16O,)28Si

First StageFirst Stage

Second StageSecond Stage

D.A

. Hut

cheo

n et

al.,

NIM

A 4

98, 1

90 (2

003)

.

ISAC I : RNBs / Stable (OLIS) 00°° spectrometer spectrometer Tof on 17 m Beam rejection 10Beam rejection 101313

Acceptance : cone half angle 20 mrad

gas/solid target system recoil detectors (DSSSD, …) BGO array ( = 50 % @ 5 MeV)

Measurements ON- and OFF resonance @ BC



Results on 12C(12C,)24Mg and 12C(16O,)28Si12C+16O

Gamma spectrum (28Si)2+ → 0+

4+ → 2+

3+,0+, 3-

~14 MeV

12C+16OHighest energy -ray

25 MeV

~ 11 MeV

0 MeV28Si

20 MeV

~ 10 MeV

0 MeV24Mg

12C+12CHighest energy -ray

~ 10 MeV

S. C. et al., Fusion 06, San Servolo, AIP Conf. Proc. 853 (2006), S. C. et al., Journal of Physics G, London (2008).

~ 14 MeV



Clusters ?

Shell Model ?16O, doubly magic …, 0+

2, 2+, 4+ …B(E2) (2+0+) = 27 W.u., B(E2) (4+ 2+) = 65 W.u.8Be, 9Be, 10Be12C (0+, Hoyle) …Model Space …

Cluster Models ?CM (Abe & Uegaki), ex : 24Mg-24Mg resonances in 48Cr.GCM, (Baye & Descouvemont), deformed structures, rotational bands.

AMD ?Ab initio (Horiuchi, Kanada En’yo)24Mg, 28Si, 32S, 36Ar, 40Ca, 28Mg Deformed structures, SD, clusters …Clusters in n-rich nuclei



Results on 12C(12C,)24Mg and 12C(16O,)28SiTheory

What is the structure of those states ?What is the structure of those states ?

28Si(12C-160) Ohkubo and Yamashita, Phys.Lett. B 578 (2004) 304. 24Mg(12C-12C) P. Descouvemont and D. Baye, Phys.Lett. 169 B (1986) 143.

Links between low-lying members of these cluster bands ?Links between low-lying members of these cluster bands ?



2+ resonance ? (Ecm = 6 MeV)

simulationexperiment

Resonances strongly correlated to 24Mg and 28Si states Large part of the flux via doorway states around 10-11 MeV. ( threshold = 9.3 MeV and 10.0 MeV)

D.G. Jenkins, S. Courtin et al., Phys. Rev. C (in press)

Results on 12C(12C,)24Mg and 12C(16O,)28Si

12C+12C12C+16O

2 scenarii 1- States with a specific structure ? 2- Decay via T = 1 states through T = 1 M1 allowed transitions may be favoured in this N = Z nucleus …



© H

. Esb

ense

n, S

. Mis

icuR → 6.05

R → 6.9

6.09 → g.s.

R → g.s.

Lower energies ?What happens below BC and down to Eastro … ?

12C() 16O, Dragon data

E

Medium mass systems fusion X-sections, hindrance … Ex : 64Ni +64Ni, incompressibility, CC calc.

36S+48Ca, LNL, Legnaro, 10/2007 (20% below BC)

12C + 12C, 12C + 16O C.L. Liang, K.E. Rehm, B.B. Back and R.V.F. Janssens, PRC 75, 015803 (2007), 16O and 12C induced fusion. S extrapolated to low energies …

12C() 16O Reaction rate, = 0.01 fb @ EGamow Direct kin. (Stuttgart, M. Assuncao et al., PRC 73 (2006) 055801), no recoil Inverse kin. (Triumf, C. Matei et al. PRL 97 (2006) 242503) recoil with Dragon, new path …



Next move

Shell model and mean field, a kind of unified view

TDHF, reaction mechanism at Bc and below as a function of the reacting time …

Identify the doorway states Giant resonances & molecular resonances … ?N-rich clusters ? new generation of scintillators (LaBr3(Ce)) + state-of-the-art spectro …

12C + 12C, why ?E



Breakup reactions 28Si 12C+16O, 24Mg 12C+12C

• 12C+16O breakup states to 45 MeV. C.J. Metelko et al., J. Phys. G29 (2003), 697 • Reaction 12C(20Ne,12C16O)@ ANL

• 12C+12C breakup states to 50 MeV C.J. Metelko et al., Phys.Rev. C68 (2003) 0544321• Reaction 12C(16O,12C12C)

RCRC

12C+16O et 12C+12C



EM transitions between resonant states

Multinucleon transfer, far from stability (collab. L. Corradi, LNL) n-pairs transfers in n-rich nuclei fus very @ low E.

SPIRAL2

PARIS

Nuclear Molecules resonances and doorway states Gammasphere+FMA, AGATA, PARIS SPIRAL 2

24 Si detectors @ 45°+ highly efficient -array


Documents

Sandrine Courtin Atelier de lESNT Saclay, Feb. 4-6 / 2008 Captures and Molecules Sandrine Courtin Institut Pluridisciplinaire Hubert Curien, Dpartement