K.U. Leuven

The Belgian Research Initiative on eXotic nuclei (BriX)

Piet Van Duppen Instituut voor Kern- en Stralingsfysica - K.U.Leuven

Belgium

• Introduction• Nuclear physics research in Belgium• Research funding

• The “Interuniversity Attraction Poles Program”: historical note

• The BriX network• “Advanced Research on Exotic Nuclei for Nuclear Physics and

Nuclear Astrophysics”• Research highlights (experimental part, theory discussed by J.-M. Sparenberg)

• Conclusion and Outlook

K.U. Leuven

• Nuclear physics research in Belgium

Federal laboratory

K.U. Leuven

• Fundamental nuclear physics research funding:

• Federal: “Interuniversity Attraction Poles Program”

• Regional:

• Universities:

• EU:

• Nuclear physics research in Belgium: funding

K.U. Leuven

• Interuniversity Attraction Poles Program

Period Partners Research Activities

1987-1991 U.C.L. – U.L.B. – K.U.Leuven

1992-1996 U.C.L. – U.L.B. – K.U.Leuven

1997-2001 U.C.L. – U.L.B. – K.U.Leuven

2002-2006 U.C.L. – U.L.B. – U.Gent - K.U.Leuven

2007-2011 U.L.B. – U.Gent – SCK•CEN -K.U.Leuven

Nuc

lear

Str

uctu

re

Nuc

lear

Ast

roph

ysic

s

-Radioactive beam production- 6He, 10,11C, 15O, 18F, 18,19Ne- Resonant laser ionization of exotic nuclei

- New instrumentation- Laser ion source- LEDA array (segmented silicon detector)- MINIBALL (segmented germanium detector array)- Penning trap for weak interaction studies

- Nuclear astrophysics: exp. and theory (e.g. 13N(p,g))

- Nuclear structure and reactions: experiment - ground-state properties (moments, charge radii)- decay studies- Coulomb excitation- fusion, fission and transfer reactions

- Nuclear structure and reactions: theory- Cluster models, few-body approaches, shell-model, mean-field, symmetry based approaches

- Fundamental interaction studies

K.U. Leuven

The Belgian Research Initiative on eXotic nuclei (BriX) (2007-2011)

• Belgian partners:

• P. Descouvemont, D. Baye, P.-H. Heenen, J.-M. Sparenberg

• K. Heyde, C. Wagemans

• H. Aït Abderrahim, P. Baeten, P. Schuurmans

• M. Huyse, G. Neyens, N. Severijns, R. Raabe, P. Van Duppen

• International partners:

• GSI (Germany)• GANIL (France)• CSNSM (France)• U.Köln (Germany)

K.U. Leuven

ISOLDE - CERN

GSI-DarmstadtGANIL-Caen

KVI-Groningen

CRC-Louvain-la-Neuve

The Belgian Research Initiative on eXotic nuclei (BriX) (2007-2011)

ILL- Grenoble

• Facilities

• Species: from neutron beams to radioactive ion beams• Energy: from ~ rest up to 50 MeV/u• Half-life: from ms to hours

K.U. Leuven

Z=28

Z=50

N=4

0Z=82

20

N=5

0

N=8

2

N

Z

Structure of light exotic nuclei

Towards 78Ni: shell structure along Z=28 and N=50

Shape coexistence along Z=82

Nuclear structure along the N=Z line

Fundamental interaction studies

n-induced and beta-delayed fission

The Belgian Research Initiative on eXotic nuclei (BriX) (2007-2011)

Feasibility study for ISOL@MYRRHA“Island of inversion around 32Mg”

• Physics

K.U. Leuven

Laser ion source

LISOL - Leuven Isotope Separator On-Line

• Louvain-la-Neuve Radioactive Beam Facility

LISOL gas cell

Laser beams

Target

Cyclotron beam

Exit hole

Sextupole Ion Guide

Ar/He from gas purifier

Filament

CYCLONE110 cyclotron• p,d,a and heavy ions• Radioactive Ion Beams

Laser System

Detection

Laser ion source• Thermalisation in a buffer gas cell (500 mbar Ar)• Resonant laser ionization: Z-selection (isomer)• Mass separation: A/Q selection

[M. Facina,- NIMB 226 (2004) 401][Y. Kudryavtsev,- NIMB 204 (2003) 336]

K.U. Leuven

• Wide spectrum of pure radioactive ion beams• Energy: from ~ rest up to 3 MeV/u

Post accelerated beams:8,9,11Li, 10-12Be, 10C, 17F, 24-29Na, 28-32Mg, 61,62Mn, 61Fe, 68Ni, 67-71,73Cu, 74,76,78,80Zn, 70Se, 88,92Kr,96Sr, 108In,106,108,110Sn,122,124,126Cd,138,140,142,144Xe, 140,142,148Ba,148Pm, 153Sm, 156Eu, 182,184,186,188Hg, 202,204Rn

F. Ames et al., Nucl. Instrum. Methods A 538, 17 (2005)F. Wenander et al., Nucl. Phys. A701, 528 (2002)O. Kester et al., Nucl. Instrum. Methods B 204, 20 (2003)

K.U. Leuven

München, Köln, Heidelberg, Darmstadt, Leuven, York, Liverpool,

Daresbury, Strasbourg,...

The MINIBALL detector array

J. Eberth et al., Prog. Part. Nucl. Phys. 46, 389 (2001)

Miniball

120Sn

REX-ISOLDE

PPAC

Beammonitor

CD – detectorDouble sided Si strip detector

(2.3 mg/cm2)

Coulomb excitation

Si barrel detector

Miniball

Transfer reactions

K.U. Leuven

9Heunbound

10Heunbound

9Li179 ms

10Liunbound

12Be23.6 ms

9Bunbound

10B 11B12B

20.20 ms

12Liunbound

9C125 ms

10C19.3 s

11C20.4 m

11Li8.5 ms

9Be10Be1.6 106 y

11Be13.8 s

12C

12N11 ms

11Nunbound

12Ounbound

N

ZStructure of light exotic nuclei: properties of key states

Beta-decay studies by implantation in a highly pixelated Si detectorand decay correlations

•Calorimetric technique:• full energy measured• low threshold• high efficiency• precise normalisation

•Measured:6He (LLN), 11Li (TRIUMF) (2n-halos)12N, 12B (KVI) (3-alpha states in 12C)8B (KVI) (spectrum of solar neutrinos)

11Li: R. Raabe,- PRL 101 (2008) 21250112N, 12B: S. Hyldegaarda,- PLB submitted6He: R. Raabe,- PRC submitted8B: analysis in progress

K.U. Leuven

11Li: deuteron emission - decay of the halo

Theory: U.L.B.

Raabe et al., PRL 101 (2008) 212501

Structure of light exotic nuclei: properties of key states

Resonance above (Va) or below threshold (Vb)Coulomb contribution (VC)

K.U. Leuven

Present status of the “Island of inversion”as deduced from static and dynamic moments measurements

“Island of inversion” around 32Mg

3212 20Mg

K.U. Leuven

Si29

Si30

Si31

Si32

Si33

Si34

Si35

Si36

Si37

Al28

Al29

Al30

Al31

Al32

Al33

Al34

Al35

Al36

Mg27

Mg28

Mg29

Mg30

Mg31

Mg32

Mg33

Mg34

Mg35

Na26

Na27

Na28

Na29

Na30

Na31

Na32

Na33

Na34

Ne25

Ne26

Ne27

Ne28

Ne29

Ne30

Ne32

F24

F25

F26

F27

F29 22

201816

P35

S36 Production of Al isotopes at GANIL

b-NMR on polarized fragment beams

g=1.532(2)

g=1.635(2)

P. Himpe et al., Phys. Lett. B 643 (2006) 257–262

Conclusion:small (<25-30 %) intruder admixture in the 33Al ground state.

3,4

3,6

3,8

4

4,2

10 12 14 16 18 20 22 24 N

m (mN) 0p-0h

exp

MCSM(50% intruder)

2p-2h

Ip=5/2+

“Island of inversion” around 32Mg: moment measurements

K.U. Leuven Mark Huyse

“Island of inversion” around 32Mg: two-neutron transfer reactionsRadioactive beam onto a radioactive target

3H(30Mg,32Mg)1H

Si barrel detector

MINIBALL germanium detector

ISOLDE - IS470: Kathrin Wimmer

K.U. Leuven

First Ionization Limit62317.4 cm-1

CuI: ground state

Cu+ + e-

1 = 244.164 nm

2 = 441.6 nm

40943.73 cm-1

2S1/2

4P01/2

65Cu

63Cu

59Cu

57Cu: 6 ions/s

Frequency [GHz]

F=1

F=2

F=2F=1

6363

( )( ) ( )

( )

AhfA

hf

A CuCu Cu

A Cum m

56Ni6.0 d

57Cu199 ms

54Co

55Ni209 ms

55Co17 h

57Ni36 h

58Ni Z=28

N=

28

• In-gas-cell laser spectroscopy of 57,59Cu: a sample of spectra

K.U. Leuven

• In-gas-cell laser spectroscopy of 57,59Cu: results

[K. Minamisono,- PRL 96 (2006) 102501]

K.U. Leuven

5/2-

3/2-5/2-

3/2-

N=40 N=40 N=50

S. Franchoo et al., PRL81 (1998) 3100, PRC64 (2001) 054308N. Smirnova et al., PRC69 (2004) 044306A. Lisetskiy et al, PRC70 044314 (2004)T. Otsuka et al., PRL 85 (2005) 232502

Experiment Theory

28

neutronsprotons

g9/2

f7/2

f5/2

40

p3/2

p1/2

“monopole interaction”

n g9/2

Z=28

Monopole interaction towards 78Ni: Cu (Z=29)

K.U. Leuven

A = 63 65 67 69 71 73

the low B(E2; 5/2- 3/2-) value from N=40 onwards indicates that the 5/2- state is essentially of single-particle character

Results: the 5/2- states

at N=40 (69Cu), the 5/2-1 states undergo a

significant loss in collectivity, are of different character

I. Stefanescu et al., PRL 100, 112502 (2008 )I. Stefanescu et al., PRL 98, 122701 (2007)

K.U. Leuven

A = 63 65 67 69 71 73

onset of collectivity related to the filling of the g9/2 neutron state.

the proposed 1/2- shows an important increase in collectivity beyond N=40;

Results: the 1/2- states

the low B(E2; 5/2- 3/2-) value from N=40 onwards indicates that the 5/2- state is essentially of single-particle character

at N=40 (69Cu), 5/2- states undergoes a significant loss in collectivity, are of different character

I. Stefanescu et al., PRL 100, 112502 (2008 )I. Stefanescu et al., PRL 98, 122701 (2007)

K.U. Leuven

3/2- 0

7529 46Cu73

29 44Cu7129 42Cu69

29 40Cu6729 38Cu65

29 36Cu6329 34Cu61

29 32Cu5929 30Cu57

29 28Cu

3/2- 0 3/2- 0 3/2- 0 3/2- 0 3/2- 0 3/2- 0 3/2- 0 3/2- 0 3/2- 0

5/2- 1028

1/2- 1107

1/2- 491

5/2- 914 5/2- 920

1/2- 475

1/2- 670

5/2- 962

5/2- 11161/2- 11705/2- 1115 1/2- 1096

5/2- 1213

7/2- 1670

9/2+ 2551

500

1000

1500

2000

25009/2+ ~25009/2+ 25269/2+ 2506

9/2+ 2720

7/2- 1871

1/2- 454

5/2- 534

7/2- 1190

7/2- 961

9/2+ 2600

5/2- 1661/2- 135

9/2+ 2385

1/2- 771

140 65

7/2- 2340

7/2- 1711

7/2- 981 7/2- 1010

7/2- 1482

7/2- 1327

7/2- 13107/2- 1398

pf5/2

pp3/2 2+(A-1Ni)

pf7/2: p(2p-1h)

N=40

N=28

Energy systematics in the odd-mass Cu isotopes

?

collective 1/2- state

pp3/2 2+(A-1Ni)

K.U. Leuven

Ground state spins, magnetic moments, quadrupole moments, charge radii

from 61Cu up to 75Cu !

73Cu, I=3/2

75Cu, I=5/2

No hyperfine anomalyratio of A-factors = constant

if correct spin used in fit

I=5/2

I=7/2

I=3/2

K.T. Flanagan et al.,

Collinear laser spectroscopy on Cu isotopes at ISOLDE

K.U. Leuven

Shape co-existence in the lead region

H. De Witte et al. PRL 98 (2007) 112501

Shape staggering

Onset of deformation

Mean square charge radii

A.N. Andreyev et al., Nature 405, 430 (2000)

186Pb104

Potential energy surface

Theory: U.L.B. – U.Gent

K.U. Leuven

Strongly-coupledmatrix elements

Band mixing

Sign, magnitude of deformation

Shape co-existence in the lead region studied with Coulomb excitation

1 12 0

1 14 2

2 12 0

1121 12 0Cd

Hg x rays

Nick Bree, Andrew Petts et al.

0+

2+

4+

0+

2+4+

0

367

1089

375

534653

Energy (keV)

Coulomb excitation @ 3 MeV/u184Hg (3 MeV/u) + 112Cd

K.U. Leuven

Bf,i Bf,e

Spontaneous fission

EC/b+

bDF

g

ggg

g

g

g

gg

aA.N. Andreyev et al.

Rare charge-particle decay studies: ISOLDE and GSI

• Fission of 180Hg observed in the beta decay of 180Tl• Unexpected asymmetric mass split (180Hg (Z=80, N=100) = 2 x 90Zr (Z=40, N=50)• Cold fission, important for the end of the r-process

Beta delayed fission

K.U. Leuven

Study of (n,f) cross section measurements

• FWHM increases with increasing fissility parameter Z2/A of the compound nucleus:

FWHM(SF) < FWHM(n,f): 0.3 MeV difference (excitation energy broadens)

• Improve data base for transmutation of minor actinides (e.g. 245Cm)• Ternary fission (e.g. 249Cf):• improve the understanding of the ternary fission process (a, t) • important source of helium and tritium gas production in nuclear reactors

C. Wagemans et al., Nucl. Sci. Engn. 160 (2008) 200 S. Vermote et al., Nucl. Phys. A806 (2008) 1

• Complementary measurements at different facilities:• thermal neutrons: high flux reactor at ILL and BR1 reactor at SCK•CEN• resonance neutrons at TOF facility at IRMM

FLIGHT PATHSSOUTH

NEUTRONTARGET

ELECTRONLINAC

FLIGHT PATHSNORD

GELINA (GEel LINear Accelerator)IRMM Geel (Belgium)

K.U. Leuven

• Detect recoiling ions in singles for bn angular correlation• Select ion energies sequentially: retardation potential

First recoil ion spectrum

Preliminary

Retardation potential (V)

124Sn recoils

proof of principle

demonstrated

system currently being upgradedand being prepared for

measurement with 35Ar in 11/2009

V.Yu. Kozlov et al., NIM B 266 (2008) 4515

S. Coeck et al., NIM A, 574 (2007) 370

S. Coeck et al., NIM A 572 (2007) 585

V.Yu. Kozlov et al., Hyp. Int. 172 (2006) 15

V.Yu. Kozlov et al., Int. J. Mass Sp. 251 (2006) 159

S. Coeck et al., NIM A 557 (2006) 516-522

WITCH Penning trap at ISOLDE – Search for scalar weak currents

K.U. Leuven

O. Naviliat-Cuncic & N. Severijns, Phys. Rev. Lett. 102 (2009) 142302

N. Severijns, I.S. Towner et al., Phys. Rev. C 78 (2008) 055501

N. Severijns et al., Rev. Mod. Phys. 78 (2006) 991

corrected ft-value for T = 1/2 mirror transitions

:

calculated from experiment

nucleus dependent nucleus independent

29P

19Ne

21Na37K

35Ar

• New value of |Vud| :

|Vud| = 0.9719(17)

0+→0+

neutron

pion

mirrors

• First consistent test of CVC from a set of nuclear transitions other than super-allowed pure Fermi

Test of CVC and new value for Vud from T=1/2 mirror decays

K.U. Leuven

S. Roccia et al., Phys. Rev. Lett., submitted

A. Knecht et al., Phys. Rev. Lett. , submitted

K. Kirch et al., NIM A (2009) in print

- present goal: | dn | < 5 x 10-28 e cm ( by ~ 2015 ; 4 experiments )

- several extensions of the Standaard Model predict values for dn in the range 10-26 10-28 e cm

- present limit | dn | < 2.9 x 10-26 e cm ( C.A. Baker et al., Phys. Rev. Lett. 97 (2006) 131801 )

- Standaard Model value for dn 10-32 e cm

(from observed CP-violation in K- and B-meson decays)

- observation of nEDM with larger value would point to NEW source of CP-violation;

- could explain matter-antimatter asymmetry in the Universe

Fundamental physics with neutrons at PSI: neutron electric dipole moment (nEDM)

K.U. Leuven

• Conclusion

• Belgian experimental nuclear physics activities under the BriX network:

• Radioactive beam production and use (from rest to 50 MeV/u)

• Broad spectrum of instrumentation, tools and techniques:• Lasers, arrays of segmented Ge and Si detectors, Penning traps• Moment and charge radii measurements, decay studies, Coulomb excitation,

transfer reactions

• Physics:• Nuclear-structure, nuclear reaction and fundamental interaction studies using neutrons and exotic nuclei

K.U. Leuven

• Outlook short and intermediate term

• Installation and use of the LISOL gas cell based laser ion source at the focal plane of the S3 project (intense heavy-ion beams, production of pure secondary beams, laser spectrocospy)

• Participation in DESIR (laser spectroscopy)

ENERGY:Energy upgrade to 10 MeV/u and lower energy capacity

INTENSITY: ISOLDE proton driver beam intensity upgrade strongly linked to PS Booster improvements including linac4

QUALITY: ISOLDE radioactive ion beam quality: broader spectrum and higher quality (purity, emittance, time structure) and isomeric beams

European Separator On-LineRadioactive Nuclear Beam Facility

K.U. Leuven

Nuclear Physics Research at the MYRRHA accelerator at SCK•CEN

• 600 MeV, 100-200 mA, D.C. proton beam (from the initial 2.5 mA for MYRRHA) • Different target materials including uranium (e.g. UC: workhorse targets at present)• Ruggedized target-ion source systems that deliver RIB @ ~50 keV:

• ECR 1+: gaseous elements (noble gases, C, N, O,..))• Surface ion source (hot cavity): alkaline and earth alkaline elements• Laser ion sources

• Long beam times (e.g. 12 weeks) for experiments that:• need very high statistics• involve many time consuming systematic measurements• hunt for very weak signals• have an inherent low-detection efficiency

• Outlook long term

ISOL target 1+ ion source

RF

-cooler

1+ low-resolution separator

1+ high-resolution separator

experiment

MYRRHAaccelerator

• In the field of fundamental interaction studies, nuclear physics, atomic physics, condensed matter research,…

• Isol@myrrha is complementary to other ISOL facilities and will be an integral part of the MYRRHA project (see talk H. Aït Abderrahim)

K.U. Leuven

Thank you for your attention

• Organization of the joined RNB-ENAM conference in 2011 in Leuven

Everybody is cordially invited.

• Outlook 2011

K.U. Leuven

N=5

0

Z=28

N=4

0

llllllll

28

50

40

llll

llllll

n

ll

llllllllll

sd-shell

1f7/2llllllll

2p1/2

1f5/2

2p3/2

sd-shell

28

50

1g9/2

40

p78Ni

p1/2 g9/2f5/2

Ni68

28 40 Ni78

28 50

Evolution towards 78Ni along N=50 Onset of deformation Z>28

J. Van de Walle et al., PRL 99, 142501 (2007)J. Van de Walle et al., PRC 79, 014309 (2009)I. Stefanescu et al., PRL 100, 112502 (2008 )I. Stefanescu et al., PRL 98, 122701 (2007)

• Coulex (up to 68Ni, 73Cu, 80Zn)• Decay studies• Laser spectroscopy studies

K.U. Leuven

Proton NumberNeutron Number

Ni

Zn

Ge

N=50 isotones

B(E2

,2+ 1

0+ 1) [W

.u.]

E(2+ 1)

[keV

]

B(E2

,2+ 1

0+ 1) [W

.u.]

E(2+ 1)

[keV

]Ni,Zn,Ge isotopes

this work

K.U. Leuven Proton NumberNeutron Number

Zn

N=50 isotones

B(E2

,2+ 1

0+ 1) [W

.u.]

E(2+ 1)

[keV

]

B(E2

,2+ 1

0+ 1) [W

.u.]

E(2+ 1)

[keV

]

Zn isotopesShell Model (1) 56Ni core :

M. H. Jensen + monopole adjusted by Nowacki(ep,en)=(1.9e,0.9e) - (U.Gent - N. Smirnova et al, 2006)