1 / 36

Production of spin-oriented unstable nuclei via the projectile-fragmentation reaction

Production of spin-oriented unstable nuclei via the projectile-fragmentation reaction. H. Ueno @RIKEN. Measurement of m & Q moments. Known nuclear moments. ground states. excited states. Data are taken from

huey
Download Presentation

Production of spin-oriented unstable nuclei via the projectile-fragmentation reaction

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. Production of spin-oriented unstable nuclei via the projectile-fragmentation reaction H. Ueno @RIKEN PST05, Nov 14-17, 2005, Tokyo

  2. Measurement of m & Q moments Known nuclear moments ground states excited states Data are taken from “Table of nuclear magnetic dipole and electric quadrupole moments”, N.J. Stone, 2001

  3. Excited states (Isomer) Ground states Method vs lifetime 1(fs) 1(ps) 1(ns) 1(μs) 1(ms) 1(s) 1(M) 1(H) 1(D) stbl TF IPAD, RIGV online AB TDPAD β-NMR IPAC CFBLS TDPAC NMR offline ME

  4. ISOL based RIBs Isotope-Separation On Line target fragmentation e.g. p+UCx • ISOL based RIBs • target fragmentation, fission, and spallation • extraction • low energies • ○ high production rates • × slow process (lifetime τ limitation) • × limited to chemically active elements (Z limitation) • ARENAS, Louvain-la-Neuve • ATLAS, Argonne • EXCYT, Catania • HRIBF, Oak Ridge • ISAC, TRIUMF • ISOLDE, CERN • PIAFE, ILL • SPIRAL, GANIL • TRIAC, KEK • TWINSOL, Notre Dame • ……..

  5. Fragmentation based RIBs • Fragmentation based RIBs • projectile fragmentation • high (intermediate) energies • ○ no limitation from τand Z • × large spread of momentum & beam divergence • RIPS, RIKEN • FRS, GSI • A1900, NSCL • LISE, GANIL

  6. Techniques of μ & Q measurements for ISOL and PF based RIBs ISOL PF • Ground states • Tilted-foil • Optical pumping (Laser) • Excited states • Coulomb excitation • Ground states • Fragmentation • Excited states • Coulomb excitation • Fragmentation

  7. Ground-state nuclear moments PST05, Nov 14-17, 2005, Tokyo

  8. after the reaction Lspectator = 0 - Lparticipant +L Fragment with High p p R p ―L Fragment with Low p Lparticipant= x R p Mechanism of the spin-polarization in P. F. reaction at the reaction (participant—spectator model) fragment (spectator) participant target

  9. Far-side trajectory Near-side trajectory Detector Detector Properties of the fragment-induced polarization • Spin-polarization can be produced simply by selectingp and Θof outgoing fragments. • Size of polarization is typically 1-5 %. • Independent of chemical properties. • Fragments can be deeply implanted into the stopper material. • × 11Be, 19C (s1/2 nature) Small-Z target Large-Z target Behavior of the spin-polarization in the P. F. reaction 14,15N→12,13B Nb Nb Au Au Al H. Okuno et al., PL B335,29 (1994)

  10. (1-AP) (1+AP) (U/D)RFoff = e- e- e- e- e- e- RF coil e- e- e- e- e- e- β-NMR • Required # of nuclei • Conventional NMR: ~1020 • β-NMR : ~104 • High sensitivity → RIB application • β-ray angular distribution: • W(θ)=1+APcosθ • A: Asymmetry parameter • P: Polarization (1+AP) (1-AP) (U/D)RFoff = NMR β-NMR method:K. Sugimoto et al., J. Phys. Soc. Japan 21 (1966) 213.

  11. Optical pumping Experimental setup at ISOLDE • Production of atomic polarization by laser • This polarization is transfered to the nuclear spin via hfi Taken from ISOLDE web site

  12. 11Be 31Mg ISOLDE

  13. RIKEN Discovery of spin-polarization in PF K.Asahi et al., PLB 251, 499 (1990) 10 μ–moments & 5 Q–moments in the neutron-rich p-shell Osaka Gr. & TITech Gr. μ[30,32Al] H. Ueno et al., PLB 615, 186 (2005) Q [31, 32 Al] (TITech Gr.) GANIL μ[ 32Cl] W.F. Rogers et al., PRC 62, 044312 (2000) 27Na, 31Al polarization D. Borremans et al., PRC 66, 054601 (2002) μ[ 31Al] D. Borremans et al., PLB 537, 45 (2002) MSU Spin-polarized RIBs @MSU P.F. Mantica et al., PRC 55, 2501 (1997) 37K polarization in single-proton pickup reaction @E=150AMeV D.E. Groh et al., PRL 23, 202502 (2003) GSI 37K polarization @E=500AMeVM. Schaefer et al., PRC 57 2205 (1998) ISOLDE μ &Q [11Li ]E.Arnold et al. PLB 281, 16 (1992) μ[11Be ]W. Geithner et al., PRL 83, 3792 (1999) μ[ 31Mg]G. Neyens et al., Phys.Rev.Lett. 94, 022501 (2005) Recent ground-state μ&Q-measurements of the unstable nuclei Fragment induced spin-polarization + β-NMR method Optical pumping + β-NMR method

  14. TDPAD γ-ray detectors B0 field Isomer-state (τ∼μs) nuclear moments target beam gμNB0 ℏ W(θ) W(θ+ • t ) stopper material spin-alignment produced in the Coulomb excitation reaction PST05, Nov 14-17, 2005, Tokyo

  15. Spin-alignment in the PF reaction • Spin-alignment is produced as a function of ejectile momentum 46Ti(E=500 AMeV) + Be → 43Sc K. Asahi et al., Phys. Rev. C 43, 456 (1991) W.-D. Schmidt-Ott et al., Z.Phys. A350, 215 (1994)

  16. F: fraction of the isomeric states F = Nisomer Ntotal Isomer ratio in the PF reaction B.M. Young et al., Phys. Lett. B 311, 22 (1993) PF is better way to produce spin-aligned RIBs

  17. TDPAD exp. at GANIL Spin-alignment produced in PF reaction 76Ge(E=61.4 AMeV)+Be → 67mNi (t1/2=13.3μs), 69mCu(t1/2=0.35μs), G. Georgiev et al., Eur. Phys. J. A 20, 93-94 (2004)

  18. Transient-field method Short-lived excited state (τ∼ ps) ferromagnet 1st target beam γ-ray detectors W(θ) W(θ+θTF) PST05, Nov 14-17, 2005, Tokyo

  19. Status ofμ(21+) measurements for unstable nuclei Transient Filed: τ～ps Low erengies • LBL • First g−factor measurement with RI beams (76Kr) K.-H. Speidel et al., Eur. Phys. J. A 25, s01, 203{304 (2005) • ISOLDE • g-Factor measurements of 132, 134, 136 Te Intermediate energies (PF reaction) • RIKEN • BTF strength @v～Zv0 H. Ueno et al.,Hyperfine Int. 136/137, 2 (2001) A. Yoshimi et al., Nucl. Pys. A 738, 519 (2004) • MSU • v/Zv0 distribution→ discussion on the BTF strengths @v ≥Zv0 A.E. Stuchbery PRC69, 064311 (2004) • g−factor measurements of 38, 40S produced in the PF reactions A.D. Davis, A.E. Stuchbery, P.F. Mantica et al., DNP2005

  20. 1st TF expeiment with RIB 1st RIB-expeiment 76Kr(T1/2 = 14.8 h) @ LBL I = 106 cps x 5 days 74Se(α, 2n)76Kr @E=38MeV Mg Beam Mg Ta Gd N. Benczer-Koller et al., Eur. Phys. J. A 25, s1.203-s1.304 (2005) Magnetic Moments of Coulomb Excited 21+ States for Radioactive Beams of 132, 134, 136Te Isotopes at REX-ISOLDE

  21. TF exp. at MSU High energy RIBs (PF reaction) A User's Perspective The Transient-Field Technique in a New Regime Andrew Stuchbery, Australian 38,40S* Au (355 mg/cm2) 38,40S (E=40 AMeV) Fe (110 mg/cm2) 38S and 40S the first 2+ states (τ∼ps)

  22. high-velocity region: vion> Zv0 N.K.B. Shu et al., PRC21, 1828 (1980) BTF=4πZ·v0/vion·μBNp G. Hagelberg et al., Z. Phys. D17, 17 (1990) VSE (eproj⇄eGdQfree) F. Hagelberg et al., PRC48, 2230 (1993) VSE (eionic-shell⇄eGdLocalized) p1s prediction BTF=p1s x q1s BTF at v > Zv0 • low-velocity region: vion≲ Zv0 • Eberhardt et al.Hyp. Int. 3, 195 (1977) • EmpiricalBTF=a·Z·vion/v0 • (a Fe=12, a Gd=17) 24Mg+Gd BTF (kT) 3 2 ? ? 1 0 5 10 15 20 Ion velocity v/vion

  23. RIKEN-setup for TF experiments • 6” NaI x 4 • Target Au+Gd • Target ladder cooled toT∼100K • Coil (Bext = 300 Gauss) • Bext Up & Down in every 15 sec. • 30 plastic scintillators for particle coincidence liq.N2 container target ladder

  24. Comparison with the systematic BTF values of 28Si and 24Mg Mg (Gd) BTF=a Z vion/v0 a=12 (Fe) a=17 (Gd) BTF=1.2(2) kT deviation but substantial magnitude Stopping power > 4.5 MeV/μm K.-H. Speidel et al. PLB324(1994)130

  25. Recent measurement of ground-state nuclear moments at RIKEN PST05, Nov 14-17, 2005, Tokyo

  26. Production of spin-polarized RI beam with RIKEN Projectile fragment Separator (RIPS) RIPS K=540 RIKEN Ring Cyclotron

  27. NMR apparatus e- e- e- e- e- e- e- e- e- e- β-NMR: w(θ)=1+APcosθ (U/D)off = (1+AP)/(1-AP) (U/D)on = (1- AP)/(1+AP) NMR technique: the AFP method

  28. Study of the p-shell nuclei through their nuclear moments TITech / RIKEN Osaka / RIKEN • g-Factors measured at RIKEN • Boron isotopes : 14B,15B, 17B • Carbon isotopes : 9C, 15C,17C • Nitrogen isotopes : 17N, 18N, 19N • Oxygen isotopes : 13O • Q-moments measured at RIKEN • Boron isotopes : 14B, 15B, 17B • Nitrogen isotopes : 18N • Oxygen isotopes : 13O Spin-parity assignment Reduction of E2 effective charges

  29. I = 0 g-factor known RIKEN ISOLDE Recent μ-measurements in the sd shell N=20 GANIL Island of inversion

  30. Neutron-rich Al isotopes (theory) 31Al 32Al 33Al 34Al 33Al Y. Utsuno et al., PRC 64(2001)011301(R) E. Caurier et al., PRC58(1998)2033 • decreases from 31Al(30Al)→33Al • E0p0h-E2p2h > 0 for Al isotopes, but similar to Mg, Na, Ne • 33Al is turning point of the inversion between 0p-0h and 2p-2h configurations along N=20 Al: near the border line of Island of Inversion

  31. μ-moments of 30Al & 32Al • The result provides a promising prospect that substantial polarizations are obtained for the other sd-shell nuclei H. Ueno et al., PL B615, 186 (2005)

  32. Comparison with shell model prediction Amplitude of intruder configurations is larger for 32Al ? In both 30Al and 32Al cases, no disagreement is observed between μexp and μSM(USD) H. Ueno et al., Phys. Lett. B 615, 186-192 (2005)

  33. Q [32Al] (preliminary) Wide-range scan Precision measurement

  34. Q [31Al] (preliminary) Wide-range scan Precision measurement 3.5σ statistics

  35. Summary • Grond-state nuclear moments have been measured in RIB facilities. • Measurements for the excited states have started. at RIKEN • Nuclear moments have been measured in the p-shell region by means of the β-NMR method + fragment-induced polarization. • μ-moments enhancement of (sd)2+, Jπ assignment • Q-moments reduction of the E2 effective charges • In the sd-shellμ[30,32 Al] and Q [31,32 Al] have been measured. • 40Ar→30Al (10-nucleon removal) was spin-polarized: P～1% • Next: 33, 35Si, Q(33Al), μ(34,35Al), 33-37P, 33Mg

  36. Collaboration H. Watanabe Australian National Univ. H. Izumi, W. Sato, T. Shimoda Osaka University H. Miyatake, Y.X. Watanabe KEK W.-D. Schmidt-Ott Universitaet Goettingen G. Neyens, S. Teughels Leuven K. Asahi, M. Takemura, G. Kijima K. Shimada, D. Nagae, M. Uchida, T. Arai H. Miyoshi, G. Kato, K. Emori, M. Tsukui Tokyo Institute of Technology H. Ueno, D. Kameda, A. Yoshimi, T. Haseyama, Y. Kobayashi,H. Sato, H. Okuno, N. Aoi, K. Yoneda, N.Imai, N. Fukunishi, A. Yoshida, T. Kubo, M. Ishihara RIKEN T. Kawamura Rikkyo Univ. H. Ogawa AIST

More Related