Post on 19-Jan-2016
description
transcript
Hiroshi MASUI
Kitami Institute of Technology
Collaborators: K. Kato Hokkaido Univ.K. Ikeda RIKEN
22-26 Aug. 2011, APFB2011, Sungkyunkwan Univ., Seoul, Korea
Matter radius of nuclei near the drip-linesAn “abrupt” change of the radius due to the
weakly bound neutron or proton
A. Ozawa 2001
Difference from typical halo nuclei: 6He, 11Be, 11Li
Core + XnCore+n (+2n)
Large Sn values of 23O and 24O ( 2.7MeV and 3.7MeV )
6He : 0.98MeV11Li : 0.38MeV11Be: 0.50MeV
23O : 2.7MeV24O : 3.7MeV
Weakly-bound neutrons Strongly-bound neutrons
22O
Sn Sn
To reproduce the drip-line at 24O
ab initio calc. + Realistic force
Effect of the thee-body interactionT. Otsuka et al, Phys. Rev. Lett. 105, 032501 (2010)
G. Hagen et al., Phys. Rev. C 80, 021306(R) (2009)
Ab initio calc. + Realistic force G. Hagen et al., Phys. Rev. C 80, 021306(R) (2009)
Coupled-cluster (2-body) + N3LO int.
-dependence: lack of many-body int.
Effect of the three-body interactionT. Otsuka et al, Phys. Rev. Lett. 105, 032501 (2010)
3-body int.
Pauli-forbidden state
Getting weakerfor more valence particle system
T. Otsuka et al, Phys. Rev. Lett. 105, 032501 (2010)
Getting weakeras the number of valence particles increases
How about the radius?
h ~ 27 MeV
b ~ 1.24 (fm)
Very small radius
G. Hagen et al., Phys. Rev. C 80, 021306(R) (2009)
Coupled-cluster (2-body) + N3LO int.
Our approaches
Role of many valence neutrons16O+Xn model m-scheme COSM + Gaussian basis
Role of last one- or two-neutrons “Core” + n or “Core”+2n modelA simplified model approach
M-Scheme COSM + Gaussian base H. Masui, K. Kato and K. Ikeda, Euro. Phys. Jour. A42 (2009) 535
•Core (16O) +Xn model space
•Gaussian radial function
•Stochastic approach for the basis set
•M-scheme approach
M-Scheme COSM approach
Wave function for the valence nucleons:
•Radial part
Product of Gaussian
•Spin-isospin part
Total M and MT are fixed
Coordinate system
We check the expectation value of the total J as <J2>
H. Masui, K. Kato and K. Ikeda, Euro. Phys. Jour. A42 (2009) 535
Expectation value of J2
J=0J=1/2
J=5/2
J=3/2
B=H=0.25
B=H=0.07
B=H=0.07
Sn for O-isotopes
NN-int.: Volkov No.2 (M=0.58)
Change the coresize with A1/6
B=H=0.07
B=H=0.25
b: 1.723 (fm)
b~A1/6
Comparison with other approaches
[3] G. Hagen et al., PRC 80 (2009)[2] B. Ab-Ibrahim et al., JPSJ 78 (2009)[1] H. Nakada, NPA764 (2006)
□: [2]
■: [1]
△: [3]+0.5(fm)
▲: [3]
○: fixed-b
●: m-COSM with b 〜 A1/6
Result of M-scheme COSM (16O+Xn model space)
•From 18O to 22O
•For23O and24O
16O-core with a fixed size + valence neutrons
16O-core with A1/6 (Mean-field-like) +valence neutrons
How large?(is the amount of the change of the radius)
Core+2n modelWe adjust the core radius and energy of the core+nsystem⇒ calculate the core+2n system
Core
Core+n
Core+2n
Fit
Rrms
E
E
(Core-n int.)
(n-n int)
Rrms
Rrms
Calc.
16O
17O (16O+n)
18O (16O+2n)
18O
19O (18O+n)
20O (18O+2n)
20O
21O (20O+n)
22O (20O+2n)
22O
23O (22O+n)
24O (22O+2n)
Results for the core+2n model
We define the difference between the calculated and experimental radii as
20O 21O
22O
Difference of the radius between Calc. and Exp.16O-17O-18O, 18O-19O-20O, 20O-21O-22O
22O 23O 24O
Difference of the radius between Calc. and Exp.22O-23O-24O
22O 23O 24O
0.238 (fm)
A schematic figure to illustrate the change of the radius of 22O
Rrms[1] 2.88±0.06 3.20±0.04 3.19±0.13
[1] A. Ozawa et al, NPA693 (2001)
Expansion of the core
Matter radius
SummaryWe studied the energy and radius of oxygen isotopeswith M-Scheme COSM and Core+2n model
1. Mean-field-like configuration with b~A1/6
2. Shrunk core size configuration until 22O
H.O. : 0p-0h configuration
Shrunk b⇒ High mom. ⇒ TOSM
It is suggested that a coupled-channel model is necessary to be introduced
The size of 22O is drastically changed when a neutron is added (23O)
Inclusion of the core excitation
TOSM in 9Li T. Myo, K. Kato, H. Toki and K. Ikeda, PRC76(2007)
2. Some config. are suppressed due to the Pauli-blocking
1. Different size for each orbit