Exotic nuclei for investigating hierarchical structure of matter

Int. Symposium on Clustering as a window on the hierarchical structure of quantum systems (CLUSHIQ2020) Jan. 23-24, 2020, Beppu, Japan

Takashi NakamuraTokyo Institute of Technology

Contents

• Multi-neutron clusters• Recent Experiments on barely unbound

2n/3n/4n emitters --- 26O,27O,28O• Near-future experiment on multi-neutron

cluster--- 10He• Summary

a-Cluster

Near Threshold àClustering

K.Ikeda, N.Takigawa, H.Horiuchi,Prog.Theo.Phys.Suppl.464.(1968).M.Freer, Rep. Prog. Phys. 70, 2149 (2007).

aa aaaa3a ++ + a

a aa a

12Cgs

+

Excit

atio

n En

ergy

Mass Number (4A)

Multi-neutron cluster near drip line?Neutron-rich Nuclei

np

continuum

Sn<1MeV

np

continuum

-1MeV<Sn<0MeVBeyond drip line

Weakly Bound/Unbound Nuclei Threshold à Clustering

9Li

11Li

n

nS2n=0.37MeV

np

VSp ~Sn~8MeV

Stable Nuclei

Halo Nucleus24O

n

n26OS2n= -0.018(5) MeV

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

A.B.MigdalStrongly correlated “dineutron” Sov.J.Nucl.Phys.238(1973).Dineutron:@ Low-dense Neutron skin/halo?/Inner crust of Neutron star?M.MatsuoPRC73,044309(2006). A.Gezerlis, J.Carlson, PRC81,025803(2010)

neutron-star

n n

Unbounda= -18.7 fm

n nS=0, T=1

s-wave scattering length

Dineutron? What happens if “two neutrons” are on the surface of a nucleus?

Possible dineutron site2n Halo Nuclei?

9Li

11Li

n

nS2n=0.37MeV

2n weakly-unbound nuclei?

24On

n26OS2n= -0.018(5) MeV

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

q 12

(deg

)r (fm)

Hagino, Sagawa, PRC93,034330(2016)

24O

28O

n

nn

n

Tetra-neutron?

4He

8He

nn

nn

4He

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

8Be

4He4He

4nn nn n

What happens if “four neutrons” are on the surface of a nucleus?

nn24O

n n

28ONon-correlated? Double-dineutrons?

nn24O n

n

28OTetra-neutron droplet?

What happens if “N neutrons” are on the surface of a nucleus? Multi-neutron cluster inside a nucleus?

E4n (MeV)0

HHe

LiBeBC

NO

FNe

NaMg

AlSi

PS

ClAr

K

Evolution Towards the Stability Limit

2n halo2/4n halo/skin

1n halo

31Ne

Ca

37Mg

26O 28O

Oxygen Anomaly

Deformation Driven Halo

N.Kobayashi et al.,PRL 2014,PRC2016T.Nakamura et al., PRL2009,2014

6He

11LiDineutron/Halo

19B

Island of Inversion

Drip Line (Weakly Bound, -Unbound Nuclei, halo, dineutron, cluster)

Shell Evolution (New/Lost Magic Number, Deformation, Shape Coexistence)Cluster Formation

21BResonances beyond drip line

Y.Kondo et al., PRL2016

S.Leblond et al., PRL2018

Big island of deformationCaurier,Nowacki,Poves,PRC2014

10He

Recent Experiments on barely unbound 2n/3n/4n emitters--- 26O,27O,28O

Yosuke Kondo, TN& SAMURAI Collaboration

HHe

LiBeBC

NO

F

26O

2n halo known4n halo/skin candidates

1n halo known28O

24O: DriplineDoubly Magic NucleusN=16: New magic number

Oxygen Anomaly

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

Spectroscopy of 25-28O—beyond the neutron drip line

T. Otsuka et al., PRL105, 032501 (2010).

Drip line Drip line

3N force: significant at N>16

Experimental study of unbound oxygen isotopes towards the possible double magic nucleus 28O

Spokesperson Yosuke Kondo

24O

23N

22C

25F 26F 27F 29F

22N21N

23O22O

20C 21C

25O 26O

31F

27O 28O

30F28F24F23F

24Ne 25Ne 26Ne 27Ne 28Ne 29Ne 30Ne 31Ne 32Ne

Z=8

N=20

G. Hagen et al., PRL108, 242501(2012).H. Hergert et al., PRL110, 242501(2013).S.K.Bogner et al., PRL113, 142501(2014).

Oxygen Anomaly

N=16?19B

Continuum Effect:A.Volya, V.Zelevinski, PRL94,052501(2005).K. Tsukyiyama, T. Otsuka, PTEP2015, 093D01 (2015).nn correlations:L.V. Grigorenko et al., PRL111,042501(2013).K. Hagino, H. Sagawa PRC89,014331(2014).

24O+2n 26O

25O+n7�0keV ?

x

E. Lunderberg et al.PRL108, 142503 (2012)C. Caesar et al.PRC88, 034313 (2013).

?

Experimental Setup at SAMURAI at RIBF

27F ~210MeV/u(from BigRIPS)

24O

n

n

NEBULA

DALI2

MWDC

Hodoscope

SuperconductingDipole Magnet(B=3.0T)

C target(1.8g/cm2)

MWDC

2 MWDCs

IonizationChamber

2Plastics

Ground state (0+)5 times higher statistics than previous study18�3(stat)�4(syst)keV Finite value is determined for the first time

1st excited state (2+)Observed for the first time1.28+0.11-0.08MeV

27F+Cà26Oà24O+2n

Decay Energy (MeV)

26O26O

N=16 shell closure (24O) is confirmedUSDB cannot describe 2+ energy at 26O

àeffects of pf shell?, continuum? 2n Correlations?, 3N force?

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

Results of 26O24O

28O measurement @ RIBF-SAMURAI

29F(from BigRIPS)

24O

n

n

NEBULA

DALI2

MWDC

Hodoscope

SuperconductingDipole Magnet(B=2.9T)

MINOSMWDC

2 MWDCs

2Plastics

n

n

NeuLAND

NeuLANDMINOS

15cm thick LH2

NeuLAND+NEBULAà ~ 50% efficiency for 1n

Towards 28O (doubly magic nucleus?) Slide by Y. Kondo

Y.Kondo, TN, T.Tomai, NIMB 463, 173 (2020).

Decay energy spectrum(24O+3n coincidence)

13

29F+1Hà24O+3n+Xn2

24O

n3

E012n1 E03

E02E01

E0123

E01<E02<E03

~1MeV

0.018MeV24O+3n 26O(0+)+n

25O+2n

27O

26O(2+)+n

Theoretical predictions towards 28O

Fig. from K. Fossez et al., PRC 96, 024308 (2017)

SM USDB: B. A. Brown, Int. J. Mod. Phys. E26, 1740003 (2017)

SM+3NF: T. Otsuka et al., PRL105, 032501 (2010)

SM+3NF sdf7/2p3/2:

CSM: A. Volya et al., PRL94, 052501 (2005), A. Volya et al., PRC74, 064314, (2006)

IMSRG: V. Lapoux et al., PRL117, 052501, (2016), H. Hergert

SM+3NF

CSM

IMSRG

SM+3NF sdf7/2p3/2

GSM

SM USDB

This work

USDB higher energy for 27O àThere are missing effects

Y.Kondo,TN PRL2016

Multi-neutron cluster experiment in the near future

– 6n cluster in 10He?

Hexa-neutron?

What happens if “six neutrons” are on the surface of a nucleus?

Non-correlated? Triple-dineutrons? Hexa-neutron droplet?

6n is more stable than 4n ?

n nn n n n

0s1/2

0p3/2

n nn n

0s1/2

0p3/2

10He

nnn

n4He

n

n10He

nn

n

n4Hen

n

10He

nn

nn4He

nn

4He+6n6He+4n8He+2n 10He

0+

02+

~1.4 MeV?

2.12 MeV3.0 MeV

Experimental Method : (p,2p) missing mass method11Li(p,2p)10He* 10He*à8He+2n, 6He+4n, 4He+6n

11Li

p 10He

)C(),( 20PnP!!

p

~200 MeV/u

)C(),( 20PnP!!

p

n

n

nn

4He

n

n6n

+ tagging 4He,6He,8He, and nn at forward detectors

Missing Mass Method:

+ Need to measure “only” projectile and two recoil protons

+ Absolute Excitation Energy (Ex) directly obtained

(Wide Ex range, Flat acceptance curve for Ex, No need of g, n coin.)

+ States with high-neutron multiplicities (eg. 6n emitter) accessible

- Worse energy resolution (1-2MeV) for a given target thickness

Compared to Invariant mass spectroscopy

à M(10He),P(10He)

T.Nakamura, H.Sakurai, H.Watanabe, Prog. Part. Nucl. Phys. 97, 53 (2017).

11Li 200MeV/u

NEBULA

n

2.9 Tesla

SAMURAI MAGNET

n

Experimental Setup

PDC1/2HODP

FDC24He

6He8He

Collaboration with TUD (A. Obertelli et al.)

Summary and Outlook

Y. Kondo, TN et al., PRL 116, 102503 (2016).à26O(0+

gs): Very weakly unbound 2n states à Correlation? Continuum?26O(2+): Found for the first time at Erel=1.28(11) MeV à Shell Evolution?

à 27,28O : Experiment Successfully Done: Preliminary Results27O: E(24O+3n)~1.1 MeV, Sequential decay through 26O(gs,0+)28O: Observed: To be shown soon

Near Future: Variety of spectroscopies along n-drip line

ü Spectroscoy of Super-heavy Oxygen àBarely Unbound 2n emitter 26O

ü Key Questions – Multi-neutron clusters on the surface of weakly bound/unbound nuclei?

4n, 6n… states? à 4n,6n… cluster?

Clustering Threshold/DriplineSemi-Hierarchy/Hierarchy

Universality?

11Li(p,2p)10He exp.Approved at RIBF

Tokyo Institute of Technology: Y.Kondo, T.Nakamura, N.Kobayashi, R.Tanaka, R.Minakata, S.Ogoshi, S.Nishi, D.Kanno, T.Nakashima, J. Tsubota, A. Saito, K.J.Cook, A.Kurihara,Y.Yoshitome, H.MikiLPC CAEN: N.A.Orr, J.G.Gibelin, F.Delaunay, F.M.Marques, N.L.Achouri, S.Leblond, Q. DeshayesTohoku University : T.Koabayshi, K.Takahashi, K.MutoRIKEN: K.Yoneda, T.Motobayashi ,H.Otsu, T.Isobe, H.Baba,H.Sato, Y.Shimizu, J.Lee, P.Doornenbal, S.Takeuchi, N.Inabe, N.Fukuda, D.Kameda, H.Suzuki, H.Takeda, T.KuboSeoul National University: Y.Satou, S.Kim, J.W.HwangKyoto University : T.Murakami, N.NakatsukaGSI : Y.ToganoUniv. of York: A.G.TuffGANIL: A.NavinTechnische Universit�at Darmstadt: T.AumannRikkyo Univeristy: D.MuraiUniversit�e Paris-Sud, IN2P3-CNRS: M.Vandebrouck

Day-one(S02,S03,S04) Collaboration—19B,20,21B,21C,22C,25,26O,…

SAMURAI21 collaboration—27,28OY.Kondo, T.Nakamura, N.L.Achouri, H.Al Falou, L.Atar, T.Aumann, H.Baba, K.Boretzky, C.Caesar, D.Calvet, H.Chae, N.Chiga, A.Corsi, H.L.Crawford, F.Delaunay, A.Delbart, Q.Deshayes, Zs.Dombrádi, C.Douma, Z.Elekes, P.Fallon, I.Gašparić, J.-M.Gheller, J.Gibelin, A.Gillibert, M.N.Harakeh, A.Hirayama, C.R.Hoffman, M.Holl, A.Horvat, Á.Horváth, J.W.Hwang, T.Isobe, J.Kahlbow, N.Kalantar-Nayestanaki, S.Kawase, S.Kim, K.Kisamori, T.Kobayashi, D.Körper, S.Koyama, I.Kuti, V.Lapoux, S.Lindberg, F.M.Marqués, S.Masuoka, J.Mayer, K.Miki, T.Murakami, M.A.Najafi, K.Nakano, N.Nakatsuka, T.Nilsson, A.Obertelli, F.de Oliveira Santos, N.A.Orr, H.Otsu, T.Ozaki, V.Panin, S.Paschalis, A.Revel, D.Rossi, A.T.Saito, T.Saito, M.Sasano, H.Sato, Y.Satou, H.Scheit, F.Schindler, P.Schrock, M.Shikata, Y.Shimizu, H.Simon, D.Sohler, O.Sorlin, L.Stuhl, S.Takeuchi, M.Tanaka, M.Thoennessen, H.Törnqvist, Y.Togano, T.Tomai, J.Tscheuschner, J.Tsubota, T.Uesaka, H.Wang, M.Yasuda, Z.Yang, K.Yoneda

Tokyo Tech, Argonne, ATOMKI, CEA Saclay, Chalmers, CNS, Cologne, Eotvos, GANIL, GSI, IBS, KVI-CART, Kyoto Univ., Kyushu Univ., LBNL, Lebanese-FrenchUniversity of Technology and Applied Science, LPC-CAEN, MSU, Osaka Univ., RIKEN, Ruđer Bošković Institute, SNU, Tohoku Univ., TU Darmstadt, Univ. of Tokyo

88 Participants (+few analysis)25 Institutes