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Excitation and decay of Isoscalar Giant Dipole Resonance

Excitation and decay of Isoscalar Giant Dipole Resonance. Introduction on Giant Resonance A schematic model of GR Excitation of ISGDR in 58 Ni ( a, a `) reaction Experimental details Data Analysis Results and discussions Summary and conclusions. A Schematic Model of GR:.

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Excitation and decay of Isoscalar Giant Dipole Resonance

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  1. Excitation and decay of Isoscalar Giant Dipole Resonance • Introduction on Giant Resonance • A schematic model of GR • Excitation of ISGDR in 58Ni (a, a`) reaction • Experimental details • Data Analysis • Results and discussions • Summary and conclusions

  2. A Schematic Model of GR: Giant Resonance: Coherent vibration of nucleons in a nucleus. The H0 to denote the Hamiltonian operator of a nucleon in the central potential of the single particle shell model. In the transition of the particle from a full shell to the one above , we must also take the particle-hole interaction into account ; the Hamiltonian operator then be written as The collective excitations appear just because of the mixing generated by this particle-hole interactions V.

  3. Nucleus Many body system with a finite size Multi-pole expansion with r, Ylm, t, s Vibration DS=0, DT=0 DS=0, DT=1 DS=0, DT=1 DS=1, DT=1 DS=1, DT=1 L=0: Monopole L=1: Dipole L=2: Quadrupole L=3: Octupole ISGMR IAS IVGMR GTR IVSMGR tr2Y0 r2Y0 tY0 t sY0 t sr2Y0 ISGDR IVGDR SDR tr3Y1 ts r3tY1 trY1 r3Y1 tsrY1 ISGQR IVGQR tsr2Y2 r2Y2 tr2Y2 LEOR, HEOR rY3, r3Y3

  4. Isoscalar Excitation Modes of Nuclear Resonance Giant Resonance: Coherent vibration of nucleons in a nucleous. Resonances due to imcompressibility :ISGMR, ISGDR Nuclear matter

  5. ISGMR, ISGDR KVI (1977) TAMU(2000) Large instrumental background! 励起の弱いISGDRを議論するには不十分。

  6. D.H. Youngblood et al., RIKEN Rev. 23, 159(1999) Y.-W. Lui et al., PRC 61, 067307 (2001)

  7. Measurement Details • 386 MeV a @RCNP 58Ni, 90Zr, 116Sn, Sm, 208Pb • 0-13 deg (Angular range) • Elastic scattering :-3.5-25 deg range.

  8. RCNP Ea=386 MeV DEa = 250 keV@FWHM Halo free beam ~10 counts/ 1nA @ empty target, 0degs.

  9. . • RCNP facility K=400 MeV ring cyclotron Grand Raiden spectrometer • Beam： • 4 He++, 386 MeV • Target: 58Ni foil 5.8mg/cm2

  10. GRAND RAIDENSPECTROMETER

  11. Instrumental Background VDC Y-position

  12. Typical Spectra Excitation Energy Spectra at 0o Angular Distribution

  13. Excitation Energy Spectrum

  14. Multipole decomposition analysis (MDA) • DWBA 計算　・・・　Ptolemy • Folding Model

  15. DWBA Formalism: Transition Potential:

  16. Transition density • ISGMR G.R.Satchler, Nucl, Phys, A472 (1987) 215 • ISGDR M.N.Harakeh, Phys. Rev. C23 (1981) 2329 • Other modes Bohr-Mottelson(BM) model

  17. 58 Ni

  18. SN1987A Transverse flow

  19. CONCLUSIONS • . A two component ISGDR strength distribution has been obtained for the first time in 58Ni • ISGDR strength distribution is in excellent agreement with recent QRPA predictions. • The value of incompressibility of infinite nuclear matter( Knm ) is 217 MeV as obtained from global systematic of present study.

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