1 / 43

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.

sauers
Download Presentation

The DESIR facility at SPIRAL2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related