takashi nakamura tokyo institute of...
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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