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

Nuclear physics research in Belgium Federal laboratory

Nuclear physics research in Belgium: funding Fundamental nuclear physics research funding: Federal: “Interuniversity Attraction Poles Program” Regional: Universities: EU:

Exotic Nuclei Nuclear Astrophysics Nuclear Structure Interuniversity Attraction Poles Program Period Partners Research Activities 1987-1991 U.C.L. – U.L.B. – K.U.Leuven 1992-1996 1997-2001 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 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 Nuclear Structure Nuclear Astrophysics Exotic Nuclei

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)

The Belgian Research Initiative on eXotic nuclei (BriX) (2007-2011) Facilities Species: from neutron beams to radioactive ion beams Energy: from ~ rest up to 50 MeV/u Half-life: from ms to hours KVI-Groningen CRC-Louvain-la-Neuve GANIL-Caen GSI-Darmstadt ISOLDE - CERN ILL- Grenoble

The Belgian Research Initiative on eXotic nuclei (BriX) (2007-2011) Physics n-induced and beta-delayed fission N=82 Z=82 Shape coexistence along Z=82 N=40 N=50 Nuclear structure along the N=Z line Z=50 Fundamental interaction studies Z Z=28 Towards 78Ni: shell structure along Z=28 and N=50 N “Island of inversion around 32Mg” Feasibility study for ISOL@MYRRHA Structure of light exotic nuclei 20

Ar/He from gas purifier Louvain-la-Neuve Radioactive Beam Facility CYCLONE110 cyclotron p,d,a and heavy ions Radioactive Ion Beams LISOL gas cell LISOL - Leuven Isotope Separator On-Line Laser beams Target Cyclotron beam Exit hole Sextupole Ion Guide Ar/He from gas purifier Filament Detection Laser ion source Laser System 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]

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)

Double sided Si strip detector The MINIBALL detector array Miniball 120Sn REX- ISOLDE PPAC Beam monitor CD – detector Double sided Si strip detector (2.3 mg/cm2) Coulomb excitation Si barrel detector Miniball Transfer reactions München, Köln, Heidelberg, Darmstadt, Leuven, York, Liverpool, Daresbury, Strasbourg,... J. Eberth et al., Prog. Part. Nucl. Phys. 46, 389 (2001)

Structure of light exotic nuclei: properties of key states 9He unbound 10He 9Li 179 ms 10Li 12Be 23.6 ms 9B 10B 11B 12B 20.20 ms 12Li 9C 125 ms 10C 19.3 s 11C 20.4 m 11Li 8.5 ms 9Be 10Be 1.6 106 y 11Be 13.8 s 12C 12N 11 ms 11N 12O N Z Beta-decay studies by implantation in a highly pixelated Si detector and 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) 212501 12N, 12B: S. Hyldegaarda,- PLB submitted 6He: R. Raabe,- PRC submitted 8B: analysis in progress

Structure of light exotic nuclei: properties of key states 11Li: deuteron emission - decay of the halo Theory: U.L.B. Resonance above (Va) or below threshold (Vb) Coulomb contribution (VC) Raabe et al., PRL 101 (2008) 212501

“Island of inversion” around 32Mg Present status of the “Island of inversion” as deduced from static and dynamic moments measurements

“Island of inversion” around 32Mg: moment measurements 29 30 31 32 33 34 35 36 37 Al 28 Mg 27 Na 26 Ne 25 F 24 22 20 18 16 P S Production of Al isotopes at GANIL  b-NMR on polarized fragment beams g=1.532(2) g=1.635(2) Conclusion: small (<25-30 %) intruder admixture in the 33Al ground state. P. Himpe et al., Phys. Lett. B 643 (2006) 257–262

“Island of inversion” around 32Mg: two-neutron transfer reactions Radioactive beam onto a radioactive target 3H(30Mg,32Mg)1H MINIBALL germanium detector Si barrel detector ISOLDE - IS470: Kathrin Wimmer Mark Huyse

First Ionization Limit 6.0 d 57Cu 199 ms 54Co 55Ni 209 ms 55Co 17 h 57Ni 36 h 58Ni Z=28 N=28 In-gas-cell laser spectroscopy of 57,59Cu: a sample of spectra 65Cu 63Cu 59Cu 57Cu: 6 ions/s Frequency [GHz] Cu+ + e- First Ionization Limit 62317.4 cm-1 2 = 441.6 nm 4P01/2 F=2 40943.73 cm-1 F=1 1 = 244.164 nm 2S1/2 F=2 CuI: ground state F=1

In-gas-cell laser spectroscopy of 57,59Cu: results [K. Minamisono,- PRL 96 (2006) 102501]

Monopole interaction towards 78Ni: Cu (Z=29) Theory Experiment N=40 N=40 N=50 5/2- 3/2- 3/2- 5/2- g9/2 “monopole interaction” 40 n g9/2 Z=28 p1/2 f5/2 p3/2 28 f7/2 protons neutrons S. Franchoo et al., PRL81 (1998) 3100, PRC64 (2001) 054308 N. Smirnova et al., PRC69 (2004) 044306 A. Lisetskiy et al, PRC70 044314 (2004) T. Otsuka et al., PRL 85 (2005) 232502

Results: the 5/2- states A = 63 65 67 69 71 73 at N=40 (69Cu), the 5/2-1 states undergo a significant loss in collectivity, are of different character 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 I. Stefanescu et al., PRL 100, 112502 (2008 ) I. Stefanescu et al., PRL 98, 122701 (2007)

Results: the 1/2- states A = 63 65 67 69 71 73 at N=40 (69Cu), 5/2- states undergoes a significant loss in collectivity, are of different character 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 the proposed 1/2- shows an important increase in collectivity beyond N=40; onset of collectivity related to the filling of the g9/2 neutron state. I. Stefanescu et al., PRL 100, 112502 (2008 ) I. Stefanescu et al., PRL 98, 122701 (2007)

Energy systematics in the odd-mass Cu isotopes 9/2+ 2720 9/2+ 2600 9/2+ 2506 9/2+ 2526 9/2+ ~2500 9/2+ 2551 2500 9/2+ 2385 7/2- 2340 2000 7/2- 1871 7/2- 1711 7/2- 1670 7/2- 1482 1500 ? 7/2- 1327 7/2- 1398 pf7/2: p(2p-1h) 7/2- 1310 1/2- 1170 5/2- 1213 7/2- 1190 1/2- 1107 5/2- 1116 5/2- 1115 1/2- 1096 5/2- 1028 5/2- 962 1000 5/2- 914 5/2- 920 7/2- 981 7/2- 1010 7/2- 961 pp3/2 2+(A-1Ni) pp3/2 2+(A-1Ni) 1/2- 771 N=40 N=28 1/2- 670 5/2- 534 collective 1/2- state 500 1/2- 491 1/2- 475 1/2- 454 pf5/2 5/2- 166 1/2- 135 140 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 65 3/2- 0

Collinear laser spectroscopy on Cu isotopes at ISOLDE Ground state spins, magnetic moments, quadrupole moments, charge radii from 61Cu up to 75Cu ! 73Cu, I=3/2 75Cu, I=5/2 No hyperfine anomaly ratio of A-factors = constant if correct spin used in fit I=3/2 I=5/2 I=7/2 K.T. Flanagan et al.,

186Pb104 Shape co-existence in the lead region Mean square charge radii A.N. Andreyev et al., Nature 405, 430 (2000) 186Pb104 Potential energy surface Shape staggering Onset of deformation H. De Witte et al. PRL 98 (2007) 112501 Theory: U.L.B. – U.Gent

Shape co-existence in the lead region studied with Coulomb excitation Nick Bree, Andrew Petts et al. 0+ 2+ 4+ 367 1089 375 534 653 Energy (keV) Coulomb excitation @ 3 MeV/u 184Hg (3 MeV/u) + 112Cd Sign, magnitude of deformation Strongly-coupled matrix elements Band mixing

a Bf,i Bf,e Rare charge-particle decay studies: ISOLDE and GSI EC/b+ A.N. Andreyev et al. Beta delayed fission a bDF g g g g g g g Bf,i Bf,e g g Spontaneous fission 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

Study of (n,f) cross section measurements 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 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 GELINA (GEel LINear Accelerator) IRMM Geel (Belgium) FWHM increases with increasing fissility parameter Z2/A of the compound nucleus: FWHM(SF) < FWHM(n,f): 0.3 MeV difference (excitation energy broadens) C. Wagemans et al., Nucl. Sci. Engn. 160 (2008) 200 S. Vermote et al., Nucl. Phys. A806 (2008) 1

WITCH Penning trap at ISOLDE – Search for scalar weak currents 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 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 system currently being upgraded and being prepared for measurement with 35Ar in 11/2009

corrected ft-value for T = 1/2 mirror transitions : Test of CVC and new value for Vud from T=1/2 mirror decays nucleus dependent nucleus independent corrected ft-value for T = 1/2 mirror transitions : calculated from experiment 29P 19Ne 21Na 37K 35Ar 0+→0+ neutron pion mirrors New value of |Vud| : |Vud| = 0.9719(17) First consistent test of CVC from a set of nuclear transitions other than super-allowed pure Fermi 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

Fundamental physics with neutrons at PSI: neutron electric dipole moment (nEDM) 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 present limit | dn | < 2.9 x 10-26 e cm ( C.A. Baker et al., Phys. Rev. Lett. 97 (2006) 131801 ) - several extensions of the Standaard Model predict values for dn in the range 10-26  10-28 e cm - present goal: | dn | < 5 x 10-28 e cm ( by ~ 2015 ; 4 experiments )  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

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

EURISOL Outlook short and intermediate term ENERGY: European Separator On-Line Radioactive Nuclear Beam Facility 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 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)

ISOL@MYRRHA Outlook long term 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 ISOL@MYRRHA ISOL target 1+ ion source RF-cooler 1+ low-resolution separator 1+ high-resolution experiment MYRRHA accelerator 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 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)

Organization of the joined RNB-ENAM conference in 2011 in Leuven Outlook 2011 Organization of the joined RNB-ENAM conference in 2011 in Leuven Everybody is cordially invited. Thank you for your attention

N=50 N=40 78Ni Z=28 Evolution towards 78Ni along N=50 Onset of deformation Z>28 llllllll 28 50 40 llll llllll n ll llllllllll sd-shell 1f7/2 2p1/2 1f5/2 2p3/2 1g9/2 p 78Ni Coulex (up to 68Ni, 73Cu, 80Zn) Decay studies Laser spectroscopy studies 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) N=40 N=50 p1/2 g9/2 f5/2 Z=28

Ni,Zn,Ge isotopes N=50 isotones this work E(2+1) [keV] E(2+1) [keV] Ge B(E2,2+10+1) [W.u.] B(E2,2+10+1) [W.u.] Zn Ni Neutron Number Proton Number

Zn isotopes N=50 isotones Shell Model (1) 56Ni core : M. H. Jensen + monopole adjusted by Nowacki (ep,en)=(1.9e,0.9e) - (U.Gent - N. Smirnova et al, 2006) Zn isotopes N=50 isotones E(2+1) [keV] E(2+1) [keV] B(E2,2+10+1) [W.u.] B(E2,2+10+1) [W.u.] Zn Neutron Number Proton Number