coulomb and nuclear breakup of halo nucleitakahiro/acon11/pdfs/nakamura.pdf(halo nuclei) ~0.5--1b

Post on 22-Jul-2020

0 Views

Category:

Documents

0 Downloads

Preview:

Click to see full reader

TRANSCRIPT

分解反応で探るダイニュートロン相関

中村隆司

東京工業大学・理工学研究科

クラスターガス状態探索のための研究戦略会議@RCNP 2011.9.7-9.8

3

Contents

Inclusive Coulomb Breakup of 22C :

1 Dineutron相関とは?

4 今後の展望

2 Dineutron相関を見るプローブ

クーロン分解、核力分解

Dineutron相関とは

A.B.Migdal “Two interacting particles in a potential well”

Sov.J. Nucl. Phys.16, 238 (1973).

n n Unbound

(Virtual State 1S0) n n

Bound nn system

In the surface of

nucleus

現代版Dineutron

BCS的対相関(長距離相関) Dineutron的対相関(BEC-ボソン凝縮的)(短距離相関)

n n n

n

Dineutron的相関

低密度下でおこる

r/r0~10-4~-5

M.Matsuo et al.

PRC73,044309(2006).

弱束縛系のDineutron -I

K.Hagino, H.Sagawa, J.Carbonell, P.Schuck

PRL99,022506 (2007).

T.Myo et al.,PRC76, 024305(2007). Esbensen Bertsch, NPA542, 310 (1992).

n

n

Dineutron configuration

n

n

Cigar configuration

M.V.Zhukov, D.V. Fedorov, B.V.Danilin,

J.S. Vaagen, J.M. Bang, NPA92,177(1992)

r1

r2 n

9Li

rc-2n

弱束縛系のDineutron -II Dineutron 相関: a|(1p)2> +b |(2s)2> + g|(1d)2> + ….

異なるParityのpairingの重ね合わせDineutron correlation

r1

r2 n

9Li

rc-2n

2

12

22

12

222

12

22

12 )1(cos)0(2)0(cos)0()1(cos)1(cos spppss abba

2

12

2 )1(cos)0(2 sp ab

2211 )0()1()Li( psCore ba

Simple two-neutron shell model

Melting of s(+ parity) and p(-parity) orbitals

90,0cos 1212 If only (1s)2 or (0p)2

%5022 ba deg5512

Correlation なし

If (1s)2 (0p)2 mixed

(N.B. Phase, 動径波動関数にも依存)

安定核におけるDineutron?

18O: l=7まで,Ex=30MeVまでの

一粒子レベルを入れた計算

(1d)2+少量(odd parity)2

dineutron相関 @Surface

K.Hagino, H.Sagawa, P.Schuck J.Phys.G: Nucl.Part. Phys. 37, 064040(2010)

18O(16O+n+n) 11Li(9Li+n+n)

本日は2中性子ハロー核のDineutronに特化

K.Hagino, H.Sagawa

Phys. Rev. C 72, 044321 (2005).

“Dineutron” という概念のまとめ

異パリティ2核子状態の重なり

(Dineutron相関の必要条件)

Dineutronの発達

低密度, 弱束縛

n

n 12<<90deg

強い相関を持つ空間的にコンパクトな2中性子系

Dineutron 相関を見るプローブ

-- クーロン分解反応

核力分解反応

2

11Li

High-Z Target

(Pb)

9Li

n g

= NE1(Ex) dB(E1) dEx

dsCB dEx 9hc

16p3

Cross section = (Photon Number)x(Transition Probability)

Invariant Mass

Equivalent Photon Method

relx , EE

)Li(),(),( 9PnPnP

11Li*

v>0.3c

C.A. Bertulani, G. Baur, Phys. Rep. 163,299(1988).

Probe-1: Coulomb Breakup

Photon absorption of a fast projectile

TN et al. PRL96,252502(2006).

W.u)6(5.4

)3MeV(18.042.1)1( rel

22

EfmeEB

Coulomb breakup and soft E1 excitation of 2n halo nuclei

--- Case of 11Li

)(24

3

)1()1(

21

2

2

2

1

2

rrrrA

Ze

dEdE

EdBEB x

x

p

Non-energy weighted E1 Cluster Sum Rule

deg48 14

1812

Soft E1 Excitation(2n-halo)—Sensitive to S2n, l ,

dineutron-like correlation

r1

r2 n

9Li

rc-2n

n

S とp の混合を反映

Experimental Result

E(9Li-n)

E(9

Li-

n)

1M

eV

Further Correlation?

E(9Li-n)

n

9Li

E(9Li-n)

1MeV

Simulation (Phase Space)

E(9Li-n)

E(9

Li-

n)

E(9Li-n)

E(9

Li-

n)

1M

eV

1MeV

Full Calc.

FSI

n-9Li 有

nn 無

FSI

n-9Li 無

nn 無

FSI

n-9Li 無

nn 有

K. Hagino, H. Sagawa, TN, S.Shimoura

PRC 80, 031301(R)(2009).

この方法 Final State Interaction にSensitive

G.S.のnn correlation にはInsensitive

Probe-II: Nuclear Breakup (momentum distribution)

14Be 12Be

n

n p target

n 13Be

)Be(14P

)Be(12P)(nP

)Be(13P

)Be(13

P

)Be(12P

)(nP

14Be: 2n Halo Nucleus

Y.Kondo,TN et al.PLB 690, 245 (2010).

70MeV/nucleon

p

s

d

E(13Be):

0.25-0.75MeV p(14Be,12Be+n)

s=103(7)mb (Erel=0-4MeV)

p

d s 12Be+n

13Be 1/2-

5/2+(3/2+)

0.51(1)MeV

2.39(1)MeV

Intruder State(Parity Inversion) E(13Be) (=Erel(

12Be+n)) (MeV) )Be(13

P

3 Inclusive Coulomb Breakup of 22C

@ RIKEN RI BEAM FACTORY

H He

Li Be B C

N O

F Ne

Na Mg Al Si

P S

Cl Ar

K

N=8

N=16

N=20

N=28

N=2

32Mg

Neutron Halo’s along the drip line?

* Estimated value by Audi & Wapstra

2n halo known

4n halo (skin)

1n-halo known

22C (S2n*=0.42(94) MeV)

31Ne (Sn=0.29(1.64) MeV) Jurado et al. PLB649,43(2007).

Island of inversion

19C

Halo?

Ex

(=Eg)

B(E1) (E1 Transition Probability)

~20MeV 1~2MeV

Soft E1 Excitation

(Halo Nuclei)

~0.5--1b <0.1b

Eth

x

x

xE dEdE

EdBEN

cE

)1()(

9

16)1( 1

3

ps

Inclusive Coulomb Breakup

s(E1)

31Ne+Pb30Ne+X

22C+Pb20C+X

Giant Dipole Resonance

(ordinary nuclei)

Halo/Non Halo can be

distintinguished only from

the inclusive cross section !

ZDS

48Ca 345MeV/nucleon

60-150pnA

SRC

BIGRIPS IRC

FRC

RRC

RIKEN RI Beam Factory (RIBF) Completed in 2007

World Largest RI-beam facility

48Ca

345MeV/nucleon

60-150pnA

19C,20C,22C ~240MeV/nucleon 31Ne ~230MeV/nucleon

Pb,C

target

TOF Br, DE

TOF,DE

Br @ZDS

Experiment at BigRIPS & ZDS at RIBF

Particle Identification : 22C20C

22C ~ 6 counts/s

1n(or 2n) removal cross section

Coulomb breakup cross section

6.27.1~

)()()1(

CPbE sss

2n Halo in 22C

1n Halo in 31Ne c.f. 19C (known halo)

Evidence for

Sn(MeV)=0.58(9) 2.93(28) Sn=0.29(1.64)

S2n(MeV)=3.51(24) 0.41(93)

Estimated

From known

B(E1)

TN.PRL83

1112(1999).

1.38(6) b

0.208(14) b

0.92(5)b

Inclusive Coulomb Breakup of 22C and B(E1)

Ex

Assume d function distribution for B(E1) dB/dEx

Ex0

s(E1)=0.92(5) barn (preliminary)

B(E1)~ 1-2e2fm2

• B(E1) distribution of 11Li (TN, PRL2006) s(E1)~1.0 barn (Erel<3MeV)

Strong Soft E1 Excitation as in 11Li

-Possible Prominent 2n-Halo above 11Li (c.f. K.Tanaka et al., PRL 104, 062701(2010))

22C+Pb

a|(2s1/2)2> +b |(2s)2>

74.3% 25.0%

a|(2s1/2)2> +b |(1d3/2)

2> + g|(2p3/2)2> + g|(1f7/2)

2> …. Correlated:

62.5% 24.2% 4.7% 3.8%

Even l only:

S2n=500keV

計算: by K.Hagino

|(2s1/2)2>

100%

No correlation:

(s only)

1.05b

2.41b

1.66b

SAMURAI 2012年始動予定 -- new spectrometer in RIBF --

Superconducting Analyzer for MUlti-

particle from RAdio Isotope Beam with

7Tm of bending power

RI beam from BigRIPS

target

superconducting

coil

pole(2m dia.)

rotate

vacuum chamber

Kinematically complete

measurements by detecting

multiple particles in coincidence

Superconducting Magnet

3T with 2m dia. pole (designed resolution 1/700)

80cm gap (vertical)

Heavy Ion Detectors

Proton Detectors

Neutron Detectors

Large Vacuum Chamber

Rotational Stage

Invariant Mass Measurement

Missing Mass Measurement

Proton Heavy Ion

Neutron

Slide: K. Yoneda

今後の展望

まとめ

• Dineutron 相関 --- 強い空間的相関をもつnn系

--異パリティ対相関の重ね合わせ

--弱束縛、低密度 (表面)

--(安定核の表面にも表れる可能性が指摘されている)

• クーロン分解法: 有力な手段の一つ <12>

Dalitz Plot むしろFinal Stateを調べる手段

• Coulomb Breakup of 22C

Inclusive CB Cross Section ~0.9barn (preliminary)

B(E1) ~1e2fm2 11Liと同程度

• Exclusive Coulomb Breakup of 22C 2012年度予定@SAMURAI

マクロな量の(より多数の)dineutronsがあったらどうなるか?

Neutron Skin Dineutron Skin?

ダイニュートロンの超流動状態が原子核の表面に?

2D超流動?

安定核のDineutronは本当にあるのか?

(RCNPで実験?) どういう場合にdineutron が出現するか?

Dineutron Skinはあるのか?

ボゾン的様相(超流動?)はあるのか?

弱束縛系(ハロー)のdineutron

vs 安定核のdineutron (違いは何、特徴は何)

Collaborators

Inclusive Coulomb Breakup of 22C

T.Nakamura, N.Kobayashi, Y.Kondo, Y.Satou, N.Aoi, H.Baba, S.Deguchi,

N.Fukuda, J.Gibelin, N.Inabe, M.Ishihara, D.Kameda, Y.Kawada, T.Kubo,

K.Kusaka, A.Mengoni, T.Motobayashi, T.Ohnishi, M.Ohtake, N.A.Orr, H.Otsu,

T.Otsuka, A.Saito, H.Sakurai, S.Shimoura, T.Sumikama, H.Takeda,

E.Takeshita,M.Takechi, S.Takeuchi, K.Tanaka, K.N.Tanaka, N.Tanaka,

Y.Togano, Y.Utsuno,K. Yoneda, A.Yoshida, K.Yoshida, K. Hagino

Backup

top related