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The DESIR facility at SPIRAL2

The DESIR facility at SPIRAL2 is an informal collaboration promoting ISOL beams for experiments with low-energy radioactive ions. It includes beam handling, laser spectroscopy, and decay spectroscopy methods. DESIR aims to study decay properties, nuclear structure, fundamental interactions, and other applications of exotic nuclei.

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The DESIR facility at SPIRAL2

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  1. The DESIR facility at SPIRAL2 • DESIR: Désintégration, excitation et stockage d’ions radioactifs • (Decay, excitation and storage of radioactive ions) • Informal collaboration to promote ISOL beams at SPIRAL2 • Result of a SPIRAL2 workshop in July 2005 on ISOL beams at SPIRAL2: • - Beam handling, beam preparation, traps: Dave Lunney (CSNSM) • Frank Herfurth (GSI) • - LASER spectroscopy: François Le Blanc (IPN Orsay) • Gerda Neyens (KU Leuven) • Paul Campbell (Manchester) • - Decay spectroscopy: Maria José Garcià Borge (Madrid) • - Atom and ion traps: Oscar Naviliat-Cuncic (LPC Caen) • Spokes-person: Bertram Blank • GANIL liaison: Jean-Charles Thomas Bertram Blank, CS IN2P3, 3-4 Juillet 2006

  2. pps pps A pps A Why another ISOL facility? • close to stable beam intensities for exotic nuclei • much higher intensities than at ISOLDE or Oak Ridge • not too far from EURISOL intensities • key nuclei like 78Ni, 100Sn, 132Sn with high intensities

  3. Conclusions of the SPIRAL2 Workshop (july 2005): Low energy RIB 1.A new experimental area of about 1500m2 located at the ground floor, dedicated to the experiments with low-energy beams from SPIRAL2 is strongly requested. The new building includes areas for the experimental equipments, acquisition and control rooms. 2. A High Resolution mass Separator (HRS) with a resolution of M/M>5000with a dedicated identification stationis absolutely necessary. A separation scheme Low Resolution mass separator → RFQ cooler → HRS is proposed. 3. The low energy radioactive beams should be available for experiments already at the beginning of the operation of SPIRAL 2. The physics program requires both neutron-rich and neutron-deficient beams. 4.More than one production target – ion source station is required to ensure flexible schedule and a possibility for fast change of the mass of radioactive beams. 5.An extension of the current LIRAT beam line in order to takefull advantage of the SPIRAL 1 beams is proposed.

  4. DESIRphysics program • Decay spectroscopy - decay properties and nuclear structure studies - particle-particle correlations, cluster emission, GT strength - exotic shapes, halo nuclei • Laser spectroscopy - static properties of nuclei in their ground and isomeric states - nuclear structure and deformation • Fundamental interactions - CVC hypothesis, CKM matrix unitarity via 0+ 0+ transitions - exotic interactions (scalar and tensor currents) - CP (or T) violation with e.g. Radium • Solid state physics and other applications

  5. SPIRAL 2 LAYOUT Production building DESIR LINAG GANIL facility LIRAT

  6. Underground J.C. Thomas, GANIL

  7. Spectroscopy of trapped beams Laser Spectroscopy Decay studies Cooling/Bunching Other purposes Fundamental Interactions DESIR: Ground-floor J.C. Thomas, GANIL

  8. Possible extension of LIRAT • Multi-beam capabilities (physics program  2012) • Tests and development for SPIRAL2 & DESIR LIRAT today Spec. b LPC Trap ? J.C. Thomas GANIL

  9. Beam handling: methods Magnetic separation (HRS) PENNING TRAP A. Jokinen, JYFL

  10. RF Beam handling: RFQ cooler and buncher RFQ-cooler: 3 p mm mrad, 0.5 eV, 10 ms, 60 % D. Lunney et al., CSNSM

  11. Beam handling: Implementation F. Varenne, GANIL

  12. Summary of decay spectroscopy experiments: The BESTIOL facility (BEta decay STudies at the SPIRAL2 IsOL facility) • Decay studies with halo nuclei • Clustering studies in light nuclei • Super-allowed b decays and the standard model of electro-weak interaction • Angular correlation measurements and standard model of electro-weak interaction • Cases of astrophysical interest • New magic numbers • Transition from Order to Chaos • Shape coexistence, deformation and Gamow-Teller distribution • High-spin isomers • Test of isospin symmetry combined with charge exchange reactions • Beta-delayed charged-particle emission: e.g. proton-proton correlation

  13. Short half-lives (10ms) • High Qb values • Low Sp/n values • Selection rules: • Fermi: DT=0 ;DJ=0 ; pf = pi • Gamow-Teller: DT=0±1; DJ=0±1; pf = pi • Reduced transition probability: Decay properties of exotic nuclei • 1916 Rutherford & Wood [Philos. Mag. 31 (1916) 379] • 1963Barton & Bell identified 25Si as p emitter • Global properties -delayedparticle emission • Very Selective probe E,  Level density Spin, Isospin -decay properties

  14. Search for exotic interactions e+ nucleus q ne • b-n angular correlation requires to measure the recoil ion + b particle • within the SM x : Fermi fraction; r : GT/F mixing ratio • beyond the SM a contains quadratic S and T contributions O. Naviliat-Cuncic et al., LPC Caen

  15. Search for exotic interactions: Production and preparation of 6He candidate: (pure GT transition) deduce bn angular correlation from measurement of b-recoil (recoil with very low energies < 1 keV) 6He+ production at SPIRAL cooling in H2 gas / bunching trapping/measuring LIRAT low energy beam line O. Naviliat-Cuncic et al., LPC Caen

  16. beta telescope PM plastic scintillator DSSSD beam monitor mCP 6He+ 10cm mCP recoil ion detector Search for exotic interactions: Setup and first results • TOF of ions extracted from trap • first time difference for b-decay RF ON/OFF (V-A theory) O. Naviliat-Cuncic et al., LPC Caen

  17. CVC, CKM, exotic currents: 0+  0+ b decays = 3073.5 (12) s(1) 3074.4 (12) s (1,2) Measurements: - Q value - T1/2 - branching ratios  Vud0+0+ = 0.9738(4)(1) 0.9736(3)(1,2,3) VusK= 0.2200(23)(PDG) 0.2254(21)(4) VubB = 0.00367(47)(PDG)  0.9987(11) (~ 2 shift) (1) Towner and Hardy, PRL 94 (2003) 092501, PRC 71 (2005) 055501 (2)Savard et al., PRL 95 (2005) 102501 (3)Marciano & Sirlin, PRL 96 (2006) 032002 (4) E865, KTeV, NA48, KLOE (PDG) Particle Data Group, S. Eidelman et al., PLB 592 (2004) 1

  18. 0+  0+ b decays: Physics output • 1. Vudmatrix element ( test of unitarity) • 2. test of CVC (constancy of Ft0+ 0+ values) • 3. right-handed currents: • -0.0005 <  < 0.0015(90% C.L.) • 4. scalar currents: Ad 3: Left Right Symm.-models W1 = WL cos - WR sin W2 = WL sin + WR cos  = m12 / m22 0.011 Ad 4: scalar currents N. Severijns et al.

  19. 0+  0+ b decays: Future studies • further improve results for “classical” isotopes • determine Ft-values for new isotopes of interest: • Tz= -1 isotopes: 18Ne, 22Mg, 26Si, 30S, 34Ar, 38Ca,42Ti • Tz=0 isotopes: 62Ga, 66As, 70Br, 74Rb, 78Y, 82Nb, 86Tc, 90Rh, 94Ag,98In • stronger limits for new physics • test and improve reliability of isospin corrections • extend CVC test to higher mass region •  needs: • -relatively pure beams ( 103 at/s) of ‘classical’ and new 0+ 0+ isotopes • - precision spectroscopy techniques (for t1/2 and BR) • - Penning traps (mainly for QEC/mass)

  20. Experiment Theory Counts Energy (keV) Study of GT strength via b-delayed proton decay: 21Mg 21Mg J.C. Thomas

  21. b+ : p→n + e+ +  d = 4.8 (4) % b- : n→p + e- +  E.C. : p + e-→n +  ft- ft+ n p n p Mirror symmetry studies  = nuc + SCC • Allowed Gamow-Teller transitions (log(ft)<6) • 17 couples of nuclei • 46 mirror transitions Average asymmetry d : 11 (1) % in the 1p shell (A<17) 0 (1) % in the (2s,1d) shell (17<A<40) J.C. Thomas, J. Giovinazzo et al. (GANIL/CENBG)

  22. Search for p-p correlation in b2p decay • Two possible decay schemes: • sequential → no angular or energy correlation • 2He type decay → angular and energy correlation •  pairing correlations, nucleon-nucleon interaction, final-state interactions…. Possible candidates: 22Al, 23Si, 26P, 27S, 31Ar, 35Ca, 43Cr, 50Ni …. • Setup: Cube-silicium • 6 DSSSD • 6 large-area • silicon det. • g detection • beam catcher • or fast tape I. Matea et al., CEN Bordeaux-Gradignan

  23. Study of decay of 31Ar at SPIRAL/LIRAT Proton spectrum • Production rate: 0.5 – 1 31Ar per second • strong contamination from 33Ar I. Matea et al., CEN Bordeaux-Gradignan

  24. } for ground and isomeric states LUMIERE: Laser Utilisation for Measurement and Ionization of Exotic Radioactive Elements • Collinear Laser spectroscopy: • - spins • - magnetic moments • - quadrupole moments • - change of charge radii • N=50, N=64, N=82, etc. • b-NMR spectroscopy: • - nuclear gyromagnetic factor • - quadrupole moment • monopole migration of proton and neutron single particle levels around 78Ni • persistance of N=50 shell gap around 78Ni • persistance of N=82 shell gap beyond 132Sn • Microwave double resonance in a Paul trap: • - hyperfine anomaly and higher order momenta • (octupole and hexadecapole deformation) • Eu, Cs, Au, Rn, Fr, Ra, Am ….

  25. Atomic hyperfine structure Interaction between an orbital e- (J) and the atomic nucleus (I,mI,QS) • results in a hyperfine splitting (HFS) of the e- energy levels n J with F DEHFS • Hyperfine structure constants: and • Collinear laser spectroscopy: DmI/mI ~ 10-2, DQS/QS ~ 10-1 for heavy elements

  26. Isotope shift measurements Frequency shift between atomic transitions in different isotopes of the same chemical element • related to the mass and size differences J2, F2 dnA,A’ J2, F2 J1, F1 J1, F1 • mean square charge radius variations with a precision ~ 10-3 • study of nuclei shape (deformation)

  27. Isotope shift and nuclear moment measurements 178Hf isomer at Orsay F. Le Blanc et al. 101Zr at JYFL P. Campbell et al.

  28. COMPLIS • onset of deformation at N=82 (slope ↔ rigidity) • shape transition (even-odd staggering) • shape coexistence • dynamical effects (vibration) Isotope shift measurements • previous experiments: N~82 N~104 F. Le Blanc et al., IPN Orsay

  29. Isotope shift measurements at DESIR • with I ~ 103-104 pps: • N~50: • neutron skin in N > 50 Ge isotopes (neutron star studies) • deformation in N ≤ 50 Ni isotopes (collectivity vs magicity) • N~82: • shape evolution for Z ≤ 50 (Ag, Cd, In, Sn) • N~64: • strongly oblate shapes predicted in Rb, Sr and Y for N > 64 • Z~40: • shape transitions predicted in the Zr region (Mo, Tc, Ru) • Rare earth elements: • large deformation and shape transitions predicted (Ba, Nd, Sm)

  30. B0 b-NMR spectroscopy b-asymmetry in the decay of polarized nuclei in a magnetic field • Zeeman splitting related to gI and QS M+I I M-I with and • resonant destruction of the polarization (i.e. b-asymmetry) by means of an additional RF magnetic field • DgI/gI ~ 10-3, DQS/QS ~ 10-2 • complementary technique to collinear laser spectroscopy • suitable for light elements(low QS values)

  31. The physics case for b-NMR on polarized 60 keV beams • polarized 60 keV beams are obtained using resonant laser excitation. • with I ≥ 5.103 pps, T½ from 1 ms to 10 s, beam purity > 50 %. • b-NMR is a sensitive and precise method to measure g-factors and quadrupole moments of exotic nuclei (ground states, isomers) with lifetimes from 1 ms up to several seconds. • combination with hyperfine structure measurements yields a unique determination of the spin (e.g. PRL 94, 022501 (2005)). • Systematic precise measurements of g-factors reveal deviations from ‘normal’ behaviourand provide information on configuration mixing or onset of deformation (breaking of shell closures). • N~50: g factor of neutron-rich Ga and Cu isotopes to determine where the inversion of the pp3/2 and pf5/2 orbitals occurs. • N~82: g.s. configuration from gI measurements.

  32. Z=40 Z=28 N=50 N=40 The physics case for b-NMR on polarized beams: nuclear structure towards and beyond 78Ni Kr Produced at SPIRALII with d-induced fission Se Ge • Evolution of n orbits • from Z=40 to Z=28: • ground state spins and moments • of 83Ge, 81Zn, 79Ni and • of 81Ge, 79Zn, 77Ni • g-factors can reveal erosion of N=50 shell closure Zn Ni Lifetime OK for b-NMR studies G. Neyens et al., KU Leuven

  33. Collinear laser spectroscopy and b-NMR • previous experiments at COLLAPS: • from the position of hyperfine transitions: spin assignment and sign of gI for the g.s. of 31Mg HFS 31Mg1+ basymmetry nRF (MHz) • from b-NMR: precise measurement of |gI| • strongly deformed intruder Ip = 1/2+ g.s. of 31Mg, G. Neyens et al, PRL 94, 022501 (2005) • from QS measurements via b-NMR: QS(11Li) > QS(9Li)  p-n interaction + halo n orbitals, D. Borremans, Ph.D. Thesis, 2004, KU Leuven R. Neugart et al.

  34. Double laser and RF spectroscopy in trap • RF scan of hyperfine transitions between Zeeman levels • No Doppler effect  accurate measurements • In a Paul trap (low magnetic field) • precise determination of the hyperfine constant A (at 10-9) : hyperfine anomaly (nuclear magnetization extension) constraining the computation of the nuclear wave function • precise determination of the hyperfine constants A, B as well as C (magnetic octupole moment) and D (electric hexadecapole moment) = high-order deformation parameters

  35. Double laser and RF spectroscopy in traps • Previous results: O. Becker et al., Phys. Rev. A48, 3546 (1993) • at DESIR (I>100 pps, T½>100 ms) • hyperfine anomaly: Au, Eu, Cs • high-order deformation in the actinide region: Rn, Fr, Ra, Am

  36. Estimated budget • Building: 6000 kEuros • - DESIR hall: 3000 kEuros • - Basement: 1000 kEuros • - Crane: 1000 kEuros • - 20 % overhead: 1000 kEuros • HRS: 816 kEuros • - RFQ cooler: 150 kEuros • - 2 magnets + power supplies: 400 kEuros • - pumps, beam lines, diagonstics: 130 kEuros • - 20% overhead: 136 kEuros • Beam handling: 1640 kEuros • - off-line source: 60 kEuros • - RFQ cooler/buncher and switch yards: 650 kEuros • - Preparation Penning trap: 460 kEuros • - in-trap decay detection system: 195 kEuros • - 20% overhead: 275 kEuros • Lumière: 972 kEuros • - Laser room with infrastructure 150 kEuros - Two lasers (dye + Ar) 180 kEuros - Collinear laser spectroscopy: 170 kEuros - ß-NMR set-up: 160 kEuros - Paul trap set-up: 150 kEuros • - 20% overhead: 162 kEuros • Decay spectroscopy: 2187 kEuros • - Four Germanium detectors: 1225 kEuros • - Fast timing set-up: 34 kEuros • - 4p charged particle array: 168 kEuros • - Neutron detection array: 400 kEuros • - 20% overhead: 360 kEuros • Fundamental interactions: 600 kEuros • - MOT trap: 350 kEuros • - in-flight decay setup: 150 kEuros • - 20% overhead: 100 kEuros • Beam lines: 3600 kEuros • ------------------------------------------------------------------------------------------------------------------------------------------------ • TOTAL: 15815 kEuros

  37. Summary • solid physics case → LOI for SPIRAL2 • very promising intensities for exotic nuclei • almost 90 participants in the « Physics with low-energy beams » • in July 2005 • with its installation a unique facility • preliminary study of building at CENBG • study of cooler/buncher and HRS at CSNSM • installation of collinear laser spectroscopy at ALTO • to be built it has to be included in « reference solution » • synergies with FAIR: DESPEC, LASPEC, MATS, NCAP

  38. Beam handling: Cooling and purification in trap REXtrap

  39. T½Exp T½Théo Beta decay dominatedby GT ~1 28 g9/2 ~1.5 69Co 70Co 71Co f5/2 ~2 • Calculation of pf-shell • with a 40Ca core. • Texp > Tthéo when N 40 p1/2 67Fe 68Fe 69Fe 70Fe p3/2 62Cr 64Mn 65Mn 66Mn 67Mn 68Mn f7/2 p n 62Cr 63Cr 64Cr 65Cr 66Cr 60V 61V 58Ti 59Ti 60Ti 59V 60V 61V 62V 63V 58Ti 59Ti 60Ti 57Sc 58Sc N=40 57Sc 58Sc Influence of g9/2 orbit near N=40 Comparison experiment/shell model code ANTOINE. Proximity of g9/2 orbital to the fp shell Plus pairing (superfluidity) important => emptyingf5/2g9/2 L. Gaudefroy et al. EPJA23 (2005)

  40. The setup: Silicon cube • 6 DSSSD detectors • ( ~75% efficiency) • 6 E detectors (b rejection) • 3 EXOGAM germanium detectors • Removable catcher I. Matea et al., CEN Bordeaux-Gradignan

  41. b-NMR at DESIR Applicable to many cases, in particular to light nuclei G. Neyens et al., KU Leuven

  42. Produced at SPIRALII with d-induced fission Ga Cu isotopes Cu N=40 N=50 ? 3/2- exp 5/2- Z=40 Z=28 The physics case for b-NMR on polarized beams: nuclear structure towards and beyond 78Ni Evolution of pf5/2 - pp3/2 levels towards and beyond N=50 in Cu and Ga  ground state spins and g-factors ! b-NMR studies G. Neyens et al., KU Leuven

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