Transcript 報告会ファイル
2nd International Conference on
Frontiers in Nuclear Structure,
Astrophysics and Reactions
(FINUSTAR 2)
Aghios Nikolaos, Crete, Greece,
September 10-14, 2007
21世紀COE外国旅費補助・成果報告会
物理学第2教室原子核理論研究室
杉本 聡
会議概要1
• 場所:
ギリシア クレタ島 アギオス・ニコラウス
Iberostar Mirabello Beach Hotel and Village
• 開催日程: 2007年9月10~14日
ミノタウロス
クノッソス宮殿
(部屋数1200以上)
アギオス・ニコラウス
会議概要2
• 参加人数: 140名
(フランス14、イタリア13、アメリカ・ベルギー・ドイツ各10、ギリシア9、
日本8、イギリス7、チェコ・フィンランド・南アフリカ各5、他22カ国44名)
• 講演数 口頭発表 78、ポスター 43
• 招待講演 21、Invited Contribution 9
核構造理論6,核構造実験10,核反応理論4,核反応
実験6,次期計画4
そのうちγ線分光関係8,天体核関係7
不安定核物理の発展
From http://www.rarf.riken.go.jp/
理研→RIBF
GSI→FAIR
GANIL→SPIRAL2
etc.
Pigmy resonance
From Aumann
6th CNS International Summer SCHOOL CISS07
P. Adrichet al., PRL 95 (2005) 132501
中性子スキンと芯核の相対的な振動運動モード
Study of the tensor correlation
in a neutron-rich sd-shell
region with the chargeand parity-projected HartreeFock methods
Satoru Sugimoto
Kyoto University, Japan
Hiroshi Toki (RCNP, Japan), Kiyomi Ikeda(RIKEN, Japan)
Tensor force
• The strong tensor force is characteristic of
nuclear many-body systems
• The tensor force (pion) plays important roles in
nuclear structure.
– The tensor force produces large attractive energy in
nuclei.
– The tensor force is responsible for the saturation
mechanism of nuclear matter.
• We want to reveal the roles of the tensor force in
nuclei.
– The effect of the tensor force on shell structure.
• Shell evolution (Otsuka, Suzuki et al.)
– The change of the tensor correlation in neutron-rich
nuclei. (テンソル力は陽子‐中性子間に強く働く)
One-pion exchange potential
V
(O P E P )
(r ) = -
fp
2
4p mp
2
1
r r r r
r r
e
t 1 ×t 2 ( s 1 ×Ñ 1 )( s 2 ×Ñ 2 )
mp r
r
ù
é
ú
ê
ì
ü
m
r
m
r
2
ú
p
p
ï
ï
ö
r ÷
1 f p r r êr r æ
e
4p
3
3 ï e
ï
ç
ú
=
t 1 ×t 2 ês 1 ×s 2 ç
d ( r )÷
+ S12 í 1 +
+
2 ý
÷
2
ê
÷
çè r
ï
ï r ú
3 4p
mp
mp r
ø
m
r
(
)
ï
ï
ú
p
ïþ
ê144444444 442 444 44444443 1444444444442
îï
4 44444444444
43ú
ê
C entr al
ë
ú
T enso r
û
r r r r
(0)
r r
r
r (2)
3 ( s 1 ×r )( s 2 ×r )
é
ù
ˆ
S 12 =
- s 1 ×s 2 = 2 4 p ê[s 1 ´ s 2 ] ´ Y 2 ( r ) ú
2
ë
û0
r
j1
å
j2
å
m1 = - j1 m 2 = - j 2
l1 j1 m1 , l 2 j 2 m 2 V
(O P E P )
l1 j1 m 1 , l 2 j 2 m 2 = 0
Tensor correlation
2p-2h correlation
Particle-hole interaction
0d3/2
0d3/2
0d3/2
1s1/2
1s1/2
1s1/2
0d5/2
0d5/2
0d5/2
0p1/2
0p1/2
0p1/2
0p3/2
0p3/2
0p3/2
Proton
Proton
Neutron
0p-0h
Neutron
2p-2h
VT
VT
Proton
Neutron
j j VT j j
j j VT j j
Attractive energy
It cannot be treated in a simple Hartree-Fock
method.
->Go beyond mean field (Charge- and parityprojected Hartree-Fock method)
It can be treated in the
Hartree-Fock method.
->ls-splitting
Charge- and parity-projected
Hartree-Fock (CPPHF) method
• Tensor force is mediated by the pion.
• Pseudo scalar (s)
– To exploit the pseudo scalar character of the pion,
we introduce parity-mixed single particle state.
(over-shell correlation)
• Isovector (t)
– To exploit the isovector character of the pion, we
introduce charge-mixed single particle state.
• Projection
– Because the total wave function made from such
parity- and charge-mixed single particle states
does not have good parity and a definite charge
number. We need to perform the parity and
charge projections before variation.
-> Charge and parity-projected Hartree-Fock
equaiton
Refs. Toki et al., Prog. Theor. Phys. 108 (2002) 903.
Sugimoto et al., Nucl. Phys. A 740 (2004) 77; PRC 75 (2007) 014317; Ogawa et
al., Prog. Thoer. Phys. 111 (2004) 75; Phys. Rev. C 73 (2006) 034301.
n
p
-
p
-
+
n
+
CPPHF results for 4He and 16O
4He
xTE
HF
1.00
(Volkov No. 1
PPHF
0.96
+G3RS)
CPPHF 0.92
16O
Etot
HF
(MV1
+G3RS) PPHF
CPPHF
Etot
KE
Vtot
VC
VT
Rm
P(D)
-27.9 49.7
-77.6
-77.6
0.0 1.45 0.00
-28.3 52.5
-80.8
-75.1
-5.7 1.45 0.68
-28.7 57.8
-86.5
-73.2
-13.3 1.42 3.22
VT
VLS
KE
VC
VCoul
V3B Rm
-123.4 228.9
-416.9
0.0
-0.2
13.4 51.5 2.57
-126.6 236.5
-423.6
-5.3
-0.2
13.5 52.5 2.55
-133.3 256.5
-440.0
-17.8
-0.2
13.9 54.4 2.52
• By performing the parity and charge projection the potential
energy from the tensor force becomes sizable value.
Sugimoto et al., Nucl. Phys. A 740 (2004) 77; PRC 75 (2007) 014317
Density and charge form factor
of 16O
Density
Charge form factor
0
0.20
10
-1
0.15
HF
CPPHF
-2
10
-3
density (fm )
10
HF
CPPHF
|F(q )|
-3
2
0.10
10
-4
10
-5
10
-6
0.05
10
-7
10
0.00
-8
0
1
2
3
R (fm)
4
5
10
0
10
20
2
-2
q (fm )
• The tensor correlation induces higher
momentum component.
30
VT and VLS per particle
in closed-subshell Oxygen isotopes
(14O, 16O, 22O, 24O, 28O)
VT and VLS
VT/A and VLS/A (MeV)
0.2
2p2h tensor correlation
0.0
-0.2
s1/2
-0.4
p3/2
-0.6
-0.8
p1/2
d5/2
0d3/2
1s1/2
d3/2
VT HF
VT CPPHF
VLS CPPHF
-1.0
12 14 16 18 20 22 24 26 28 30
16O
Mass number
• The potential energy from the tensor force has the same order in
magnitude as that from the LS force.
• The tensor potential energy decreases as neutron numbers.
• Excess neutrons around 16O does not contribute to the 2p2h
correlation because there are no protons in the sd shell.
0d5/2
0p1/2
0p3/2
0s1/2
Mixing of the opposite parity
components in single-particle states
0p1/2 1s1/2
0s1/2'
0d3/2
1s1/2
0p3/2'
0.2
Pmix
0p1/2'
0d5/2
0d5/2'
0.1
1s1/2'
0p1/2
0p3/2
0d3/2'
0.0
14
16
18
20
22
24
Mass Number
26
28
16O
Because the tensor correlation is exploited by parity mixing, the mixing
probability of opposite parity components is one of the measure for the strength
of the tensor correlation.
j=1/2 states are affected largely by the tensor correlation.
If a next j=1/2 orbit is occupied newly, the mixing probabilities of the j=1/2 orbit
reduce by a blocking effect.
The excess neutrons around 16O do not contribute the tensor correlation
strongly.
0s1/2
ls splitting and the tensor force
• The effect of the tensor force on ls splitting
– HF correlation: Tarbutton et al.(HF),
Bouyssy et al.(Relativistic HF), etc.
– Shell evolution induced by the tensor force.(Otsuka,
Suzuki, Abe, Utsuno, etc)
– 2p2h correlaton: Terasawa and Arima, Andō and
Bandō, Myo et al., etc.
• Does ls splitting change in neutron-rich nuclei?
– The experiment at RIKEN
(Michimasa et al. PLB 638 (2006) 146)
D(d) in 17F(16O+p) ~ 5 MeV
→ D(d) in 23F(22O+p) ~ 4 MeV
• We study the effect of the tensor force on the lssplitting with the Hartree-Fock method.
Sugimto et al. PRC (to be published); arXiv:0705.1419
0h
V
1 d
Vl s
r dr
V
0g
0f
50 M eV ,
ls
1
0.5fm
2
( l 1) for l j 1 / 2
2
1
l for l j 1 / 2
2
Dl s l 1 / 2
Klinkenberg RMP 24 (1952) 63
The effect of the tensor force
on ls-splitting
j =l+1/2
>
j<=l-1/2
j<’
VT()
j>
VT()
j>’
j<
j>’
j<
j>
VT reduces ls-splitting.
j<’
VT enhances ls-splitting.
1. j<-j<’ or j<-j<’: repulsion
2. j<-j>’: attraction
3. If both j<’ and j>’ orbits are fully
occupied the tensor force does not
act.
cf. Bouyssy et al. PRC 36 (1987) 380
Otsuka et al. PRL 95 (2005) 232502
j<’
VT()
j>’
j<
j>
VT does not act.
17F(16O+p)
23F(22O+p)
VT()
VT()
0d3/2
1s1/2
0d3/2
1s1/2
0d5/2
0d5/2
0p1/2
0p3/2
0p1/2
0p3/2
0s1/2
The tensor force does not act
0s1/2
The tensor force reduces
the ls splitting
Michimasa et al.
(from NPA 787 (2007) 569)
3/2+
0d3/2
1s1/2
0d5/2
5 MeV
23F
5/2+
17F
Bohr & Mottelson vol. 1
Effective Interaction in the HF cal.
• Central part
Modified Volkov No.1, m=0.59
• LS part
iW 0s [ k 21 d ( r12 ) k 12 ]
d-LS:
W0=115 MeV fm5
to be determied to reproduce D(0p3/2-1-0p1/2-1)
cf. Gogny force D1
• Tensor part
G3RS
7.2MeV
3/2+
5MeV
<VLS>~-3MeV
<VLS>~+4.5MeV
4.2MeV
3/2+
<VLS>~-3.3MeV
5/2+
5/2+
17F
23F
23F
VLS+VT
only VLS
VLS+VT
<VT>~-1.8MeV
<VT>~1.3MeV
• The tensor force reduces the ls-splitting.
cf. D(0d5/2-0d3/2)= 6~7.5 MeV
in 40Ca
VT
0d3/2
1s1/2
0d5/2
Shell evolution induced by the
tensor force?
Otsuka et al. PRL 87 (2001) 082502
Summary
• We study the 2p2h tensor correlation with the CPPHF
method.
• The tensor correlation induces high-momentum
component in single-particle wave functions.
• The 2p2h tensor correlation becomes smaller with
neutron number.
• The tensor force reduces the ls-spitting for the proton
d-orbits by 3MeV in 23F. This reduction is important to
explain the experimental value in the Hartree-Fock
method.
• We also study the effect of the 2p2h tensor
correlation on the ls-splitting with the PPHF method.
It does not affect the ls-splitting largely.