np pairing in N=Z nuclei

-> effect of spin orbit

-> fp shell nuclei

Alpha clusterisation in medium-mass nuclei

(N=Z and N≠Z nuclei)

-> in the ground state

-> only symmetric matter ?

M. Assié, B. Le Crom, L. Lefebvre (IPN Orsay)

Study of pairing and quartetting

In medium mass nuclei

Matsuo et al, PRC (2006)

Rad

ius

(fm

)

halo skin

Size of nn pair vs. density

Neutron density

BEC-BCS:di-neutron

low density

BCS : Cooper pairs

normal density

Prot

on d

ens

ity

unbound neutrons

>> Low density = Halo & skin nuclei like 6He, 11Li & 8He

▶ nn pairing in infinite nuclear matter (T=1 channel)

Infinite nuclear matter : T=1 pairing

Neutron density

BEC-BCS:di-neutron

low density

BCS : Cooper pairs

normal density

Prot

on d

ens

ity

unbound neutrons

Size of deuteron pair

Normal density

Lom

ba

rdo

et

al,

PR

C (

20

01

)

pn Cooper pairs

deuteron

>> d pairing appears close to normal density in nuclei ?

▶ nn pairing in infinite nuclear matter (T=1 channel)

▶ The symmetric nuclear matter and T=0 pairing

Infinite nuclear matter : T=0/T=1 pairing

▶ nn pairing in infinite nuclear matter (T=1 channel)

▶ The symmetric nuclear matter and T=0 pairing

▶ In nuclei : Effect of spin-orbit on T=0 pairingT=1 T=0 overlap

Sambatoro, Sandulescu, Johnson, PRC (2015)

sdshell

fpshell

Neutron density

BEC-BCS:di-neutron

low density

BCS : Cooper pairs

normal density

Prot

on d

ens

ity

unbound neutrons

pn Cooper pairs

deuteron

In nuclei : T=0/T=1 pairing

▶ nn pairing in infinite nuclear matter (T=1 channel)

▶ The symmetric nuclear matter and T=0 pairing

▶ In nuclei : Effect of spin-orbit on T=0 pairingT=1 T=0 overlap

Gezerlis et al, PRL (2011)

Sambatoro, Sandulescu, Johnson, PRC (2015)

sdshell

fpshell

In nuclei : T=0/T=1 pairing

Bertsch, Luo arXiv:0912.2533v1

stable unstable

T=1

T=0

30P

76Sr

136Er

Deuteron-transfer intensitiesfrom IBM model

T=0 pairing by transfer reaction

van Isäcker, PRL (2005)

transfer is proportionnal to the number of pairs

dσ (0+)/dσ (1+)= gives the relative strength of T=0/T=1 pairing

Case of 44Ti g.s.

from A.O. Macchiavelli, Eurisol Topical meeting

T=0 pairing by transfer reaction

Transfer reaction

Best nucleus to study : . N=Z nuclei with high j orbitals to develop collectivity

g9/2 shell like 92Pd not accessible experimentally

. only sd and fp shell nuclei available

reaction beam E direction selectivity

(p,3He) >20 MeV forward ΔT=0,1

(3He,p) low <5MeV backward ΔT=0,1

(d,α) >20 MeV forward ΔT=0

(α,d) low <5MeV backward ΔT=0

• New measurements of (3He,p) and (p,3He) in sd shell @ RCNP Osaka (see J. Lee’s talk next session)

• Measurement of 44Ti from A.O. Macchiavelli

44Ti

Th

is e

xp

eirm

ent

52F

e, 5

6N

i

Transfer measurements : where do we stand ?

New experiment@GANIL to extend the systematics 56Ni and 52Fe (p, 3He)

from

A.O

. M

acch

iave

lli

Motivations & meaurement

• Beam produced by fragmentation with the LISE spectrometer

• Reactions measured : 56Ni (p,3He) 54Co56Ni (d,4He) 54Co52Fe (p,3He) 50Mn

• thick targets : 7 mg/cm2

• Odd-Odd nucleus level Scheme

56Ni, 52Fe @ 30A MeV

54Co

0+, T=1197keV (isomeric)

936 keV, 1+, T=0 1445 keV, 2+, T=11821 keV, 3+, T=0

MUST2

TIARA- HYBALL

Pairing in the T=0 or 1 np channel : GANIL experiment

MUST2

Generic Level scheme

0+, T=1

isomeric state

1+, T=0 (d transfer)

2+, T=1

Efficiency ~8%@ 1 MeV

Energy resolution 3 keV

Doppler broadening 80keV

MUST2

Pairing in the T=0 or 1 np channel : GANIL experiment

56Ni(p,d) reaction for calibration

0 10 20 30 40

100

50

0

θlab (deg.)

Ela

b M

eV)

-10 -8 -6 -4 -2 0 2 4 6 8 10Excitation energy

56Ni(p,d)

Kinematical line

846 keV FWHM(in agreement with simulations)

56Ni(p,d) already measured @ MSU (Sanetullaev et al, PLB 2014)

energy calibration of MUST2 alignement CATS-MUST2 resolution = 846 keV (FWHM) as expected

56Ni (p,3He) 54Co 52Fe (p,3He) 50MnE* resolution = 450 keV

g.s.

g.s.1+ 1+

Excitation energy Excitation energy

Pairing in the T=0 or 1 np channel

Pairing in the T=0 or 1 np channel

56Ni (p,3He) 54Co 52Fe (p,3He) 50MnE* resolution = 450 keV

in coinc. with 3He in coinc. with 3He

54Co

0+, T=1197keV (isomeric)

936 keV, 1+, T=0

1445 keV, 2+, T=1

1821 keV, 3+, T=0

1+0+

2+1+

3+2+

1+0+

2+0+

50Mn

0+, T=1225keV (isomeric)

651 keV, 1+, T=0

800.1 keV, 2+, T=1

1143 keV, 3+, T=0

44Ti

np pairing in 56Ni

56Ni

Fit of E* assuming no contribution of isomeric state

(p,3He)

• comparison with 52Fewithin the sameexperimental conditions iscoming• estimation of isomeric

state contribution

E* (MeV)

0+

1+ 2+3+

Quartetting vs. np pairing

Neutron density

BEC-BCS:di-neutron

low density

BCS : Cooper pairs

normal density

Prot

on d

ens

ity

unbound neutrons

pn Cooper pairs

deuteron

Quartetting in infinite nuclear matter

alpha

Normal density

>> Experimental aspects : N=Z nuclei -> spectroscopic factors

▶ Competition between T=0 pairing and quartetting in infinite matter

▶ Effect of spin-orbit in nuclei ? fp shell nuclei favored for alpha clusterization ?

Roepke et al, PRL (1998)

Alpha clusterisation in the g.s.

The case of 8Be (g.s.)

Pronounced alpha cluster structureρ/ρ0=1/3

Wirin

ga

et al P

RC

(20

00

)LAB frame intrinsic frame

r(fm)

z(f

m)

Alpha cluster structure of g.s. of light nuclei

Ex : 6Liα

d

Heavier N=Z nuclei

Alpha clusters at the surface

-> enhancement of reaction cross-sections ?

36Ar*

J-A. Scarpaci et al PRC (2010)L. Lefebvre et al, Proceedings Bormio 2013

Probing alpha clusters in 40Cathrough nuclear break-up

p

40Ca

40Ca(40Ca,40Ca+LCP) @ 50 MeV/ASPEG + 240 INDRA CsI

eg/cm2ESPEG =350 keVE(36Ar*)=1.15 MeV

Experimental set-ups

40Ar(40Ca,40Ca+LCP) @ 35 MeV/ASPEG + 8 MUST2 + EXL

eg/cm2ESPEG =350 keV, EMUST2 =50 keVE(36Ar*)=500 keV

PhD of L. Lefebvre

Statistical decayof an excited stateCASCADE

4+

?

Q

E36Ar=Emiss-S

Spectra for 36Ar(*): invariant mass method

40Ca @ 50A.MeVE*(40Ca)

v

v40Ca

40Ca

Emiss= E*- EKcm- EKcm

36Ar

40Ca 36Ar

E*

g.s.

E

Sp

36Ar*

Alpha clusters in 40Ca : angular distribution

θlab

40Ca

36Ar

Statistical decay

Direct decay through the Towing Mode(one step process)

Nuclear only

Direct decay through the Nuclear break-up (one step process)

J.A.Scarpaci et al., Physics Letters B428 (1998) 241

Einit

Efin

Etarget Enucleon

Side emission

Theoretical description of the one-particle break-upTDSE description

di H

dt

2

( ( )) ( ( ))2

cible C projectile pH V r r t V r r tm

Time Dependent Schrödinger Equation

D. Lacroix et al, NPA(1999)

Probability density of a

nucleon WF

(44 MeV/A,b= 8 fm)

Buck potential (Buck, PRC 1995)

To reproduce rotationnal bands in 40Ca

WS potential

B. Buck et al., Phys. Rev. C (1995)

K.F. Pal & R.G Lovas, Phys. Lett. B, (1980)

6s, 5d, 4g waves

Alpha clusters in 40Ca : spectroscopic factors

40Ca

SF = 2.0 +/- 0.5 % for 36Ar (g.s.)= 1.9 +/- 0.9 for 36Ar*(2+)= 1.3 +/- 0.9 for 36Ar*(4+)

SFincl.~ 3.9 +/- 0.7

TDSE calculation

θlab

GS = 0+, 40Ca = An p, Innn

nå

nÄ 39K*, Jn

pn +

… + Cn a, Innn

nå

nÄ 36Ar*, Jn

pn

40Ca(d,6Li) SF~13%!!! (18% for 2+, 37% for 4+) Umeda et al. NPA429, (1984),

Shell Model Calc SF~4%Chung et al. PL 79B, 381, (1978)

SF(2+)SF(0+)

SF(4+)SF(0+)

40Ar

P z (M

eV

/c

Px (MeV/c

Statistical decayof target

Nuclear break-up

Alpha clusters in 40Ar : angular distribution

θlab

dσ

/dΩ

(μ

b/s

r)

TDSE calculation

40Ar

dσ

/dΩ

(μ

b/s

r)

SFincl.~ 4.0 +/- 2.5

Alpha clusters in 40Ca & 40Ar : SF

40Ca

SFincl.~ 3.9 +/- 0.7

TDSE calculation

θlab

Essentially no difference between symmetric and asymmetric matter

θlab

dσ

/dΩ

(μ

b/s

r)

TDSE calculation

40Ar

dσ

/dΩ

(μ

b/s

r)

SFincl.~ 4.0 +/- 2.5

THANK YOU

IPNO : B. Le Crom, M. Assié, J.A Scarpaci, D. Beaumel, Y. Blumenfeld, M-C Delattre, L. Lefebvre, E, M. Chabot, N. de Séréville, S. Franchoo, J. Guillot, F. Hammache, P. Morfouace, I. Stefan, D. Suzuki, M. Vandebrouck,G. Verde

GANIL : Ph. Chomaz, A. Chbihi, D. Lacroix, P. Roussel-Chomaz, J. Frankland,B. Bastin, E. Clément, G. de France, T. Roger, O. Kamalou, L. Perrot, J. Pancin,O. Sorlin, J-C Thomas

LPC Caen : L. Achouri, J.C. Angélique, M. Aouadi, F. Delaunay, Q. Deshayes, J. Gibelin, S. Leblonb, N. Orr, X. Perreira, M. Marquès

CEA/Saclay : A. Corsi, A. Gillibert, V. Lapoux, E.C. Pollacco, M. de Sénoville

University of Santiago de Conpostela : B. Ferandez-Dominguez, M. Camano, D. RamosUniversity of Surrey : W. Catford, A. Matta, A. KnaptonUniveristy of Camerino : D. MengoniUppsala University : J. NybergUniversity of lusbon : A. Benitez-SanchezINFN-LNS : M. FisichellaHoria Hulubei National Institute of Physics : F. Rotaru, M. Stanoiu, R. Borcea