systematic study of the many- particle and many-hole states in and around the island of inversion -...
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Systematic study of the many-particle and many-hole states in
and around the Island of Inversion
- #N=Odd system -M. Kimura(Hokkaido)
Introduction: Island of InversionIsland of Inversion: N ~ 20 Ne, Na, Mg isotopes Topics: large deformation, mpmh config., shell gap
quench
N=21 isotone: 31Ne(binding limit), 33Mg Topics: spin-parity, p-wave halo, neutron orbital
N=21 isotone
•Odd-mass(neutron) system reveals neutron-orbital, shape coexistence in the Island
•The last neutron particle (hole) orbital has strong influence on nuclear properties
•In N=21 isotone, 0f7/2 and 0d3/2 orbials take part in the game
Island of Inversion
Theoretical Framework: AMD
A-body Hamiltonian
Parity projected Slater determinant
Single particle wave packets
Variational parameters
Gogny D1S
Theoretical Framework: AMD
Angular momentum projection
GCM
Generator Coordinate: quadrupole deformation b
Hill-Wheeler eq.
Energy curves in and around the Island
• ph configuration depends on neutron #• Relative energy between ph states depends on the proton number
The Island
Results: 0+ and 2+ states (N=20 isotones)
• Strongly deformed 2p2h takes over the ground state
• Note that 0p0h, 2p2h and 4p4h appear in the Island
• 4p4h (more deformed) also participates in.
• Some experimental evidences
Results: 0+ and 2+ states (Z=10,12 isotopes)
2p2h dominates in N=20, 22 system
4p4h (4hw)appears only in N=20 isotopes
Intermediate character
of N=18 isotopes
Precursor in N=18 system
Results: 1- and 3- states (N=20 isotones)
Great reduction of 3p3h energy
1p1h is not so sensitive to the proton number
Results: 1- and 3- states (Z=10,12 isotopes)
Great reduction of 1hw excitation energy
Due to the reduction, de-excitation is also
possible in the island
• Precursor in N=18 system
Introduction: Particle Hole Config. (N=19 System)
1p-removal from 32AlD. Miller, et.al.,Phys. Rev. C 79, 054306 (2009)
31Mg
0p1h1p2h2p3h3p4h
M. K. Phys.Rev. C 75, 041302 (2007)
J p = (3/2, 5/2)+
b-decays 33Na(N=22,g.s.) → 33Mg(g.s.)
33Mg(g.s.) → 33Al(N=20, g.s.)
J p = 3/2-
magnetic-moment: m=-0.7456mN
1n-removal: p3/2
S. Nummela, et. al., PRC64, 054313 (2001)
V. Tripathi, et. al., PRL101,142504 (2008)
D. T. Yordarov, et. al., PRL99, 212501 (2007)
R. Kanungo, et. Al., PLB685, 253 (2010)
Introduction: Spin-parity of 33Mg(N=21)
Introduction: 1n Halo of 31Ne(N=21)
1n-Removal Exp. : Large cross section : Observed large cross
section can be explained with small Sn and l=1,2
Large Reaction cross section M. Takechi, et. al., Nucl. Phys. A 834, (2010), 412
T. Nakamura, et. al., PRL103, 262501 (2009)
Halo?
Results: Spectrum of 33MgConsistent with magnetic moment exp. AMD underestimates number of very low-lying
states
Sn=3.2MeV
Results: B(E2) of 33MgCoulomb Excitation Exp. : B.V. Pritychenko, et. al., PRC65,
061304(R) (2002).
Large cross section for 485keV stateAuthors assumed Jp=5/2+ for the ground state (no information was available at
that time except for b-decay data that suggested positive parity)
Large cross section does not contradict to AMD (Further exp. is required.)
Results: Spectrum of 31Ne
Sn=250keV
Same Jp with 33Mg, but much smaller Sn3/2+ is almost degenerated (Ex=120keV)
Summary and Plan
Summary33Mg has negative-parity ground state with J=3/2AMD agrees with magnetic moment and COULEX
experiments, but contradict to b-decayb-decay of 33Na should feeds 4p3h config. of 33Mg31Ne also has negative-parity ground state with J=3/2 and very small Sn. J=3/2- is almost degenerated.
PlansSmall Sn, but no Halo ! (fault of AMD, RGM calc. to
see it)
p-n interaction dependence of level-ordering
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