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Geometry of Two-Proton-Halo Candidate Nucleus . 大石知広 (M2) ° 、 萩野浩一 東北大学大学院・理学研究科・物理学専攻 ( 2009.8.28. 三者若手夏の学校). Introduction (1). nucleus has a t ypical feature of “ Borromean ” nuclei, such that. → unbound,. or. but. → bound as . Introduction (2).
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Geometry of Two-Proton-HaloCandidate Nucleus 大石知広(M2)°、萩野浩一 東北大学大学院・理学研究科・物理学専攻 (2009.8.28.三者若手夏の学校)
Introduction (1) nucleus has a typical feature of “Borromean” nuclei, such that → unbound, or but → bound as .
Introduction (2) Two protons are considered to have the “halo-like” structure around the core . ? or Its geometry is an interesting topic, in connection to 1.di-proton correlation in weakly bound system, 2.two proton emission.
Introduction (3) For two-neutron-halo nuclei, e.g. : Ref[1]:K.Hagino, and H.Sagawa, PRC72(‘05)044321 How does Coulomb repulsion affect the halo-structure?
Model (1) Three-body model Hamiltonian:
Model (2) Assumption: (1).This time, I study only the g.s. of : (2).Core is spherical, and proton-Core interaction = Woods-Saxon + Coulomb: ※
Model (3) (3).Proton-proton interaction =δ-interaction + Coulomb:
Procedure (1) Solve the single-particle Schrödinger eq: (2) Using as basis, diagonalize the total Hamiltonian. • Calculate some expectation values, e.g. ,etc… and density-distributions of two protons.
Parameter-setting (1) Woods-Saxon potential: Where . . . to reproduce energy levels of .
Parameter-setting (2)a To determine , I need (1).energy cutoff : (2).nn-scattering length: Ref[2]:H.Esbensen, G.F.Bertsch, and K.Hencken, PRC56(‘97)3054
Parameter-setting (2)b ※are determined to reproduce the binding energy difference between and :
Geometrical properties The total Hamiltonian is diagonalized in the truncated space, determined by . I will calculate g.s.properties of .
Results (1) Geometrial values: Ref[3]:C.A.Bertulani, and M.S.Hussein, PRC76(‘07)051602(R) Occupation probability:
Results (2) Density distribution as a function of and the angle , weighted with :
Summary •In the g.s. of , d(5/2)-wave is dominant, and two protons tend to couple with S=0. •Both S=0 & S=1 component have radial tail, characteristic in halo nucleus. →Coulomb effect? •The expectation value of angle is . However, it should be interpreted with a care, because of the 3-peaked structure of density.
Future works •Reproduce the resonance energies of for accuracy of single-particle states. •Construct excited states, i.e. coupling. •Study about the dipole-excitation: or two-proton-emission.