(B02 Exotic nuclei for - - PowerPoint PPT Presentation

中村隆司 Takashi Nakamura Tokyo Institute of Technology

Kickoff Symposium, “Clustering as a window on the hierarchical structure of quantum systems”, O-Okayama Campus, Tokyo Institute of Technology, Nov. 19-20, 2018

エキゾチック核子多体系で紐解く物質の階 層構造 (B02班） Exotic nuclei for investigating hierarchical structure of matter (Grp-B02)

Contents

• Introduction
• Dineutron Cluster
• Semi-hierarchy at the neutron-rich limit
• Spectroscopy of Oxygen isotopes
• Planned Experiments – Multi-neutron cluster
• Summary and perspectives

126 82 28 Nuclear Chart

Towards the neutron-rich limit

Origin of matter (Nuclear Astrophysics) Neutron Nubmer N Proton Number Z Where is the boundary of existence of nuclei? How the nuclear properties (shell, collectivity) change? New Phenomena due to weak binding, change of surface Neutron Halo/Skin Dineutron, Neutron droplet Neutron Matter New Paradigm 28 8 2 20 8 2 50 20 50 82

n-star

Neutron-rich Nuclei: Can be a bridge to a neutron star

SRC IRC fRC RRC RILAC ECR CSM GARIS & GARIS2 AVF RILAC2 RIPS BigRIPS ZeroDegree SAMURAI SHARAQ SCRIT KISS SLOWRI Rare RI Ring

2007~ SRC: World Largest Cyclotron (K=2500 MeV) High-Intense Heavy Ion Beams up to 238U at 345MeV/u

• eg. 48Ca: ~700pnA (~4x1012pps) ~10 times compared to 2008

238U: ~70pnA (~4x1011 pps) ~103 times compared to 2007

RI Beam Factory (RIBF) at RIKEN

The New-generation RI-beam facility in the world

In-Flight RI Separator with large acceptance 113 Nh (Nihonium) K.Morita et al. Production of RI beams: Fragmentation/ Inflight Fission

“Dineutron cluster” in neutron-rich nuclei

Dineutron exists in Nuclei? “dineutron”-states can be semi-hierarchy?

Clustering and Hierarchical Structure of Matter

 Threshold: Clustering near

ar T Threshold  Semi-Hierar archy y

 Degree of Freedom：Neutral

alizat atio ion of Char arge, Spin(S), ), Isospin(T)

 Degree of Separation: : Compositeness, Spectroscopic fac

actor N+ 𝐿 u d s L(1405) Hadron Quark Hadron Molecule L

0Color Charge

N

Ex Ex ExLarger Neutron Halo

n n

Hadron Nucleus

11B(5p+6n)

0S

9Li+2n 11Li(3p+8n)

N/Z>2 N/Z~1 N/Z≫ ∞ E E A=const. N/ZLarger dineutron cluster Hoyle State a a a Hadron a cluster Nucleus

12C(gs)

0 S, T

3a Ex Ex ExLarger

Multi-neutron correlation (neutron cluster) near drip line Neutron-rich Nuclei n p

continuum

Sn<1MeV n p

continuum

• 1MeV<Sn<0MeV

Beyond drip line

Weakly bound/unbound nuclei --- Threshold (Unitary limit) Clustering Halo Nuclei Weakly Unbound Nuclei

4n: “Tetra neutron” E4n=0.83±0.65(stat)±1.25(syst) MeV

K.Kisamori et al., PRL116, 052501 (2016)

26O: “Weakly Unbound 2n” 24O+2n E2n= 0.018±0.003(stat)±0.004(syst) MeV

Y.Kondo et al., PRL116,102503(2016).

9Li

11Li

n n

S2n=0.37MeV

n p

V Sp ~Sn~8MeV

Ordinary Nuclei

Halo Nucleus

Threshold

4n

A.B.Migdal Strongly correlated “dineutron”

• n the surface of a nucleus

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

Dineutron: @ Low-dense Neutron skin/halo? /Inner crust of Neutron star?

Dineutron?

M.Matsuo PRC73,044309(2006). A.Gezerlis, J.Carlson, PRC81,025803(2010)

neutron-star

n n

Unbound a= -18.7 fm

n n

S=0, T=1 Possible dineutron site

2n Halo Nuclei?

9Li

11Li

n n

S2n=0.37MeV 2n weakly-unbound nuclei?

24O

n n

26O

S2n= -0.018(5) MeV

Kondo, TN et al., PRL116,102503(2016). T.Nakamura PRL96, 252502 (2006). q12 (deg) r (fm)

Hagino, Sagawa, PRC93,034330(2016)

s-wave scattering length

What happens if there are ‘multiple’ dineutrons?

24O

28O

n n n n

Dineutron-cluster? a a a

Hoyle state a+8Be 3a 285keV 93keV 7.65MeV

12C

Dineutron-condensation?

alpha-condensation?

A.Tohsaki, H.Horiuchi, P.Schuck,G.Ropke, PRL 87, 192501 (2001).

24O+4n 26O+2n 28O

~18 keV

??

12C(0+ 2)

alpha-cluster

Dineutron Clustering & Hierarchy

Dineutron-cluster hierarchy (made of dineutron-cluster)

n n n n

Normal nuclear hierarchy (made of nucleons)

Surface-region: Core-region:

28O

Dineutron-cluster hierarchy: Semi-hierarchy?

Naïve Picture n n n n

10He

n n

H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K

Evolution Towards the Stability Limit

2n halo known 4n halo/skin 1n halo known

31Ne

Halo? Where is the neutron drip line? How does nuclear structure evolve towards the drip line? What are characteristic features of drip-line nuclei? Shell? Deformation?

Ca

37Mg 26O

Drip Line? Continuum?

N=28 N=20 N=16

Oxygen Anomaly

Deformation Driven Halo

N.Kobayashi et al., PRL 112, 242501 (2014). TN et al., PRL 112, 142501 (2014).

6He

Multi-neutron cluster candidates

28O 10He 13Li 21B

Previous Experiments 我々の先行研究

Spectroscopy of Super-heavy oxygen isotopes

• -Barely Unbound 2n emitter 26O

& 4n emitter 28O

Yosuke Kondo, TN et al.

) C ( ), ( ), (

20

P n P n P   

24O

) C ( ), ( ), (

20

P n P n P   

24O

Knockout Reaction/Quasi-Free Reaction

27F 24O

n n

26O 27F(12C,pX)26O 24O+2n 29F(p,pp)28O

24O+4n

29F

n n p

28O

n n

24O

) C ( ), (

20

P n P   ) C ( ), (

20

P n P   ) C ( ), (

20

P n P   ) C ( ), (

20

P n P   C ( ), (

20

P n P   ) C ( ), (

20

P n P   Invariant Mass Method ) C ( ), (

20

P n P   p ) C ( ), (

20

P n P   p

Invariant Mass Method: + High Yield, + Good Resolution ~ a few 100 keV

• Require Measurement of All the Decay Particles

Missing Mass Method: - Low Yield, - Worse Resolution ~ a few MeV + Measurement of projectile and recoil protons only Review: T.Nakamura, H.Sakurai, H.Watanabe, Prog. Part. Nucl. Phys. 97, 53 (2017). ~210MeV/u

12C

p

Experimental Setup at SAMURAIat RIBF

27F ~210MeV/u

(from BigRIPS)

24O

n n NEBULA DALI2 MWDC Hodoscope Superconducting Dipole Magnet (B=3.0T) C target (1.8g/cm2) MWDC 2 MWDCs Ionization Chamber 2Plastics

Ground state (0+) 5 times higher statistics than previous study 18±3(stat)±4(syst)keV Finite value is determined for the first time 1st excited state (2+) Observed for the first time 1.28+0.11

• 0.08MeV

27F+C26O24O+2n

Decay Energy (MeV)

• Y. Kondo et al., Phys. Rev. Lett. 116, 102503, (2016)

Result of 26O

24O+2n 25O+n

0+

1.28(11) MeV 18(5) keV 749(10) keV

25O+ n 26O

(2+)

24O+4n 25O+3n 26O+2n

E Centrifugal Barrier dineutron correlation?

24O

n n

28O measurement @ RIBF-SAMURAI

29F

(from BigRIPS)

24O

n n NEBULA DALI2 MWDC Hodoscope Superconducting Dipole Magnet (B=2.9T) MINOS MWDC 2 MWDCs 2Plastics n n NeuLAND

NeuLAND MINOS

15cm thick LH2 NeuLAND+NEBULA  ~ 50% efficiency for 1n

Towards 28O (doubly magic nucleus?)

Planned Experiments in this project

n n n n

10He

n n

Multi-neutron 4n and 6n states in extremely neutron-rich nuclei beyond the neutron drip line RI-beam 10He, 21Be, 28O 4n,6n

n n n n

28O

nn interaction >> 2n-2n interaction (Strong Inside) (Weak Outside) (Semi)-Hierarchy

Strong Inside, Weak outside? 中は強く、外は弱く?

6n 2n

) C ( ), ( ), (

20

P n P n P   

4He

11Li(p,pp)10He* 10He*8He+2n, 6He+4n, 4He+2n 11Li

n n p

10He

n n

4He

) C ( ), (

20

P n P   ) C ( ), (

20

P n P   ) C ( ), (

20

P n P   ) C ( ), (

20

P n P   p ) C ( ), (

20

P n P   p

Invariant Mass Method: + High Yield, + Good Resolution ~ a few 100 keV

• Require Measurement of All the Decay Particles

Missing Mass Method: - Low Yield, - Worse Resolution ~ a few MeV + Measurement of projectile and recoil protons only ~200 MeV/u

) C ( ), (

20

P n P  

n n

) C ( ), (

20

P n P  

) C ( ), (

20

P n P  

Submitted to RIBF NP-PAC in Oct. First exp. Focusing on 10He: 6n states

“6n” mass can be also extracted

Doctor Thesis of T. Tomai

CATANA PLUS and STRAßE

Si Trackers CsI(Na) Scintillators (E detector)

Construction Proposal: Submitted to RIBF NP-PAC in Oct. TN, A. Obertelli (TU Darmstadt) et al.

“Large-acceptance missing mass setup at SAMURAI”

CATANA PLUS

Bridge between nuclear/hadron hierarchies & Deeper understanding of nuclear system/hierarchy

r1,2

1.5 1.0 0.5 2.0

π

2π, σ

r1

ω, ρ

r1 r2

2N system 3N system

Intermediate: ∆ Intermediate: N*, ∆∆,…

Unified understanding with s-quark

Many-body force in vacuum

Long range Short range Few-nucleon system compare exp. data with rigorous calc. (Faddeev)

nuclear matter nuclear structure

Many-body system (in medium)

In-medium 2-body force

multi-n (2n,3n,4n,…)

SR repulsion Vertex corr. to OPE Vertex corr. to SR-2NF

High density Low density NN scatt. in medium experimentally deduce 2NF in nuclear medium

• T. Wakasa若狭智嗣
• K. Sekiguchi 関口仁子

[fm]

r2 r2 r2 r1 r1 r2

K.Sekiguchi T.Wakasa

Three-Nucleon ucleon Force ce (3N 3NF) F)

Key element to fully understand nuclear phenomena

2N 2NF 3N 3NF

Key probe to understand from quark hierarchy to nuclear / hadron hierarchies

3N 3NF 2N 2NF

Binding Energies of Nuclei EOS for Neutron Star

Fujita-Miyazawa 3NF (1957)

• most famous picture -
• Iso-spin states of

T=3/2 3NFs are expected to be important. However, not known well.

: excited state of nucleon

• A. Akmal et al., PRC 58, 1804 (1998)

S.C. Pieper PRC 64, 014001(2001)

Kimiko Sekiguchi (関口仁子）

v

Polarized proton beam

Planned Research

Study of three-proton/ n/ne neut utron n force (iso-spin states of T=3/2) via New Probe of Few-Nucleon Systems proton+3He scattering systems three-neutron systems : e.g. 3H(3H,3He)3n at RIBF

proton+3He experiment at RCNP

Polarized 3He Target

✦ First experim

imen ent t : p+3He at 135 MeV

✦

Next Step

✦ Energy dependent study ✦ Complete Set of Spin Observables

=> Determine T=3/2 3NFs.

Kimiko Sekiguchi (関口仁子）

Summary

 Dineutron  2n/4n/6n states in medium/vacuum Semi-hierarchy  Experimental Plan: 1st experiment: 11Li(p,pp)10He  Experiments on 3N force (Sekiguchi)  Experiments on 2N force in medium (WakasaTalk)

Near-future Perspectives

 Construction of CATANA+ : CsI(Na) Arrays: To be constructed 2018-2019  Silicon tracker (Strasse): 2019-2020 Collaboration with A.Obertelli (TUD) Construction Proposal/ Experimental Proposal submitted to RIKEN-PAC  Next Step: Investigations on Other multi-neutron systems: 13Li, 28O

Collaboration with Other Groups

 Further Inputs from Theories Dineutron-decay can be a probe of more correlations? Theoretical Investigation on the cluster-relevant reactions

e.g. If 11Li=4He+t+”4n”: 11Li(p,pp)10He can be considered as t(p,pp)”nn” + 4He+4n?)

 Universality among Dineutron, Diquark, Ultra-cold atom (unitary limit)  WS?

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