Nuclear Tidal Waves Daniel Almehed Stefan Frauendorf Yongquin Gu Yang Sun
Classical Quadrupole Surface Vibration
Tidal wave
Yrast line of 5D-harmonic oscillator In the rotating frame: small oscillations around E I qp. excitations Tidal waves
Anharmonic oscillator E(5) like I Anharmonic oscillator
I-1/2 rotor tidal wave vibrator
N= 92 90 88 86 84 No good vibrator!
Theoretical methods Fix the angular momentum or rotational frequency Find the static shape – use a mean field method Angular momentum projection: Projected shell model Cranking model: semiclassical treatment of angular momentum
Low-spin waves
F. Courminboeuf et al. PRC 63 (00) 014305
QQ model +cranking Energy minimum (self-consistency) at: harmonic
Cranking model B(E2,I->I-2)[(eb)^2] I exp calc tidal wave 0.09 0.07 AMR B(E2,I->I-2)[(eb)^2] I exp calc tidal wave 0.09 0.07 0.18 0.17 6 0.24 0.22 antimagnetic rotor 0.15 0.10 0.11 0.10 16 0.12 0.10 Experiment: M. Piiparinen et al. NPA565 (93) 671 F. Courminboeuf et al. PRC 63 (00) 014305 R. Clark et al. private communication
Projected shell model
Monopole Pairing+Quadrupole Pairing+QQ model Zero quasiparticle version: Two quasiparticle version: Diagonalize H in the basis Minimize lowest energy
Projected shell model B(E2,I->I-2)[(eb)^2] I exp calc tidal wave 0.09 0.07 0.18 0.13 0.24 0.16 antimagnetic rotor 0.15 0.14 0.11 0.15 16 0.12 0.16 AMR Tidal wave
Antimagnetic rotor
Geometrical model for an antimagnetic rotor
A. Simons et al. Phys. Rev. Lett. 91, 162501 (2003)
High-spin waves Combination of Angular momentum reorientation Triaxial deformation
yrast D. Cullen et. al
25 26 TAC 27 28 Line distance: 20keV 29 30
Line distance: 200 keV
Less favored vibrations Tidal wave Mixed with p-h excitations
s o t m K=0 0 8 14 21 24 i m t s o K=25 i (130 ns) P. Chowdhury et al NPA 484, 136 (1988) i m t s o
Tidal waves Yrast mode in soft nuclei at low and high spin Angular momentum generated by shape change at nearly constant angular velocity. Shape change: Axial, triaxial quadrupole, orientation, octupole … Rotating mean field gives a reliable microscopic description No new parameters Experimental rotational frequency well defined
Cranking model B(E2,I->I-2)[W.u.] I exp calc tidal wave AMR B(E2,I->I-2)[W.u.] I exp calc tidal wave 23.0 (15) 18 46 (6) 43 6 62 (20) 56 antimagnetic rotor 39 (2) 25 29 (3) 25 16 25 25
Projected shell model B(E2,I->I-2)[W.u.] I exp calc tidal wave 23.0 (15) 18 46 (6) 33 6 62 (20) 41 antimagnetic rotor 39 (2) 36 29 (3) 16 25 AMR Tidal wave