B02 B02 - - PowerPoint PPT Presentation

不安定核でさぐる中性子星の核物質 B02班報告

中村隆司 東京工業大学

２０１７年２月１６－１８日、第５回ウィンタースクール研究会

B02班：中性子過剰な中低密度核物質の物性

Takashi Nakamura

中村隆司, 栂野泰宏, 近藤洋介, 小林信之* 四方瑞紀, 尾崎友志, 齋藤敦美, 坪田潤一、斗米貴斗、 平山晃大, 安田昌弘, 山田啓貴, 松本真由子, 東工大 下浦享, 木佐森慶一他, ＣＮＳ東大

公募研究 計画研究

寺西高, 九州大学 関口公子, 東北大 民井淳, 阪大RCNP 山口貴之, 埼玉大 小澤顕, 筑波大学 板橋健太, 理研

B02班：中性子過剰な中低密度核物質の物性

*現：阪大核物理研究センター

EOS

Equation of State of Nuclear Matter E=E(ρ,δ)

Energy/nucleon Hydrostatic Equilibrium (General Relativity: T.O.V. Eq.) + EOS

à Radius, Maximum Mass, Mass-Radius Relation of N Star

Self-Gravity(Attractive) Pressure (Nuclear/Hadronic Interactions, + Fermi motion) Stiffer(Softer) EOS à Pressure is high(low) à Larger(Smaller) mass is sustainable

P = ρ2 ∂E ∂ρ

A=N N=Z S(ρ)?? E(ρ,δ) J EOS of Nuclear Matter

EOS of nuclear matter using Atomic Nuclei (nucleonic D.O.F)

p Direct determination of S(ρ) and EOS p Provide Basis of EOS with non-nucleonic D.O.F

δ = ρn − ρp ρ0 ≈ N − Z A

A.B.Migdal Strongly correlated “dineutron”

• n the surface of a nucleus

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

Dineutron: @ Low-dense neutron skin/halo? /surface of neutron star?

Dineutron?

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

n-star

n n

Unbound a= -18 fm

n n

S=0 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).

Hagino, Sagawa, PRC93,034330(2016)

Mixture of d2,s2,p2

θ∼1/l

(s)2 +(p)2 +(d)2+… (s)2

Approaches to Neutron-Star Physics

PDR

p S(ρ) : J, L(pressure), Ksym(Incompressibility) ß Collective Motion of Neutron-rich Nuclei—Neutron Skin

Core

n-skin Pygmy Dipole Resonance (E1)

p S(ρ)ßNuclear force (density dependence, isospin dependence, 3N/4N force) ß Tetra neutron, Exotic nucleonic system p S(ρ)ßBulk Property ß Masses, Radii Yamaguchi,Ozawa

4n 26, 28O

Y.Togano, M. Shikata, Ozaki, CATANAà PDR of 50,52Ca, àTogano’s Talk PDR/M1 of Stable Nuclei Tamii et al. 4n, Kisamori, Shimoura PRL116, 052501 (2016). 26O, Y.Kondo et al. PRL116, 102503(2016). 3N force àSekiguchi et al.

p Superfluidity ßDineutron correlation in low-dense matter— Halo

n n Coulomb Breakup of 2n Halo 22C and 19B Deformed Driven Halos: 31Ne,37Mg TN et al., PRL112,142501(2014). N.Kobayashi, TN et al.,PRL112, 242501(2014).

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) Heavy Ion Beams up to 238U at 345MeV/u (Light Ions up to 440MeV/u)

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

238U: ~30pnA (~2x1011 pps) ~103 times compared to 2007

RI Beam Factory at RIKEN

In-Flight RI Separator with large acceptance

1 CNS, The University of Tokyo

• K. Kisamori2, S. Shimoura,
• H. Miya2,
• S. Michimasa, S. Ota, T. Fujii, S. Go,
• S. Kawase, M. Kobayashi, Y. Kubota2,
• C. S. Lee2, Y. Sasamoto, M. Takaki,
• L. Tang, H. Tokieda, K. Yako,
• R. Yokoyama

2 RIKEN Nishina Center

• H. Baba, M. Dozono, N. Fukuda,
• N. Inabe, D. Kameda, T. Kubo,
• M. Kurata-Nishimura, H. Sakai,
• M. Sasano, H. Sato, Y. Shimizu,
• H. Suzuki, H. Takeda, S. Takeuchi,
• T. Uesaka, Y. Yanagisawa
• -SHARAQ06 Collaboration--

7

3 Kyoto University

• T. Kawabata, T. Baba, M. Tsumura

4 RCNP Osaka University

• E. Ideguchi, K. Miki, A. Tamii

5 CYRIC, Tohoku University

• M. Itho

6 Tokyo Institute of Technology

• Y. Kondo

7 University of Miyazaki

• Y. Maeda

8 the University of Tokyo

• T. Nishi

9 NSCL, Michigan State University

• S. Noji, A. Stolz,

10 Kyushu University

• S. Sakaguchi2

11 IPN Orsay

• D. Beaumel, M. Assie, F. Hammache

12 National Institute of Radiological

Sciences

• H. Matsubara

Tetra Neutron State Populated by 4He(8He,8Be) Reaction

n pure neutron matter neutron star

4n

Why tetra neutron?

Clarify whether the four-neutron system, “tetra neutron”, can exist as a resonance state

Ab-initio calculation

• Bound 4n cannot exist
• Possible resonance state 2 MeV
• S. C. Piper, Phys. Rev. Lett. 90,

252501 (2003) Universality of few-body Fermion system Neutron-rich Λ nucleus K.Kisamoro,S.Shimoura et al.

4n in breakup of 14Be : Marques et al. PRC 65 (2002) 044006

Design of the Experiment

p Reaction : 4He(8He,8Be)4n

9

p

Missing-mass spectroscopy

ü SHARAQ spectrometer at RIBF

→ high resolution: ~ 1 MeV

ü 2α detection at 200 MeV/u

→ good signal-to-noise ratio

・Reaction with unstable beam

→ 4n system with small momentum transfer. (almost recoil-less condition) 4n

8He 8Be 4He

Compensate Q=

• 30.9 MeV

Q= +27.7 MeV Target Projectile K.Kisamoro,S.Shimoura et al.

E E drift plane cathode pad anode wire Plastic Scintillator

• y direction

Multiplexer discri. ADC T/H (trigger)

• - --

LUPO x direction CRDC 2 CRDC 1 １ 2 FADC V １ 2 t Disc. Disc. (FPGA) 2 １

SHARAQ Spectrometer Liquid He target 8He beam (2 Mcps; 190 A MeV) α α part of collaborators Readout system of 2α (8Be) CNS-RIKEN-Tokyo-TITech-Kyoto- Tohoku-Osaka-Kyushu-Miyazaki-NIRS- IPNO-NSCL Slide by S.Shimoura

Experimental Results

Counts/ 2 MeV

2 4 6 8 10 12

(a)

(MeV)

• 20
• 10

10 20 30 40 50 60 background × 10 continuum + background 7 direct decay resonance wave packet just after reaction

E4n

K.Kisamori, S.Shimoura et al., PRL 116, 052501 (2016).

Spectroscopy

• f Barely Unbound 2n emitter 26O

(& Other studies on unbound oxygen isotopes)

Yosuke Kondo et al.

25,26O: Y. Kondo et al., Phys. Rev. Lett. 116, 102503, (2016)

Study of unbound nuclei 25O and 26O at SAMURAI

• 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 22N 21N 23O 22O 20C 21C 25O 26O 31F 27O 28O 30F 28F 24F 23F

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+n

7５0keV ?

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 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+Cà26Oà24O+2n

Decay Energy (MeV)

26O 26O

N=16 shell closure is confirmed USDB 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)

26O Results

Masses of Oxygen Isotopes Beyond the dripline

24O+2n 25O+n

0+

E Centrifugal Barrier 1.28(11) MeV 18(5) keV 749(10) keV

25O+ n 26O

(2+)

Extremely weakly UNBOUND state!

27O+n 28O

E

Weakly Unbound 4n Emitter or not?

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

Doubly Magic Or not?

?

Strong 2n correlation? Strong 4n correlation? Or 2x 2n correlation?

24O

n n

S2n= -0.018(5) MeV

Kondo et al., PRL2016

24O

n n n n

27,28O measurements in 2015

(SAMURAI21)

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

Slides: Y.Kondo

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 LPC CAEN: N.A.Orr, J.Gibelin, F.Delaunay, F.M.Marques, N.L.Achouri, S.Leblond, Q. Deshayes Tohoku University : T.Koabayshi, K.Takahashi, K.Muto RIKEN: 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.Kubo Seoul National University: Y.Satou, S.Kim, J.W.Hwang Kyoto University : T.Murakami, N.Nakatsuka GSI : Y.Togano

• Univ. of York: A.G.Tuff

GANIL: A.Navin Technische Universit¨at Darmstadt: T.Aumann Rikkyo Univeristy: D.Murai Universit´e Paris-Sud, IN2P3-CNRS: M.Vandebrouck

Day-one Collaboration

SAMURAI21 collaboration—27,28O

Y. Y.Ko 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, 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-French University of Technology and Applied Science, LPC-CAEN, MSU, Osaka Univ., RIKEN, Ruđer Bošković Institute, SNU, Tohoku Univ., TU Darmstadt, Univ. of Tokyo

88 Participants 25 Institutes

(Near-)Future Perspectives

n n

S=0

n n n n n n

Ø Dineutron Clustering? àMulti-neutron cluster? Ø Dineutron Signal?

α cluster

12C* Hoyle State 4He(=α）

proton/neutron

Formation of matter

time

BigBang

Strong interaction

Scale EM

>>102 MeV ∼102 MeV ∼10 MeV ∼ eV

ud quarks

e- e-

Nucleus quark Nucleon (Baryon) Atom Molecule

12C(gs)

Clustering and Hierarchy of matter

クラスター化ßà ßà階層構造？

Hadronization à Color charge=0 Hadronization (clusterization) Alpha clustering T=0, S=0 Dineutron clustering? T=1, S=0 Partially neutralized Formation of Atom à Electric charge=0

29F+pàp+p+28O

à24O+4n

29F

(from BigRIPS)

24O

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

MINOS

CATANA CATANA p p

29F

Tag the 28O states by the missing mass Look at the nn nnn nnnn correlation

Dineutron Signal?

Hagino,Sagawa, PRC93,034330(2016).

p nn decay from “Dineutron correlation”

core

n n

Spatially compact nn à larger relative momentum

n n θnn~180 deg

“dineutron ” 40cm 40cm 12cm

HIME(HIgh resolution detector array for Multi-neutron Events)

σx=σy~1.2cm, σz~0.6cm, σt~0.2ns ΔErel~200 keV (FWHM) @1MeV

4cm

2cm 1.0m

Recoil proton tracking àTest exp. Successful !

Direct measurement of multi-neutrons Multi-neutron tracker for future exp.

n n n n p p p p p p

Range of proton above 30 MeV > 9mm Tracking of recoil protons -> iden=fica=on of cross talk from a single neutron

1

n n p

6 mm 3 mm

中性子によって散乱された陽子を のセグメント化されたシンチレータで測定し、 そのトラックから中性子の反応位置と時間を決定する。 x y z

X-Y-T-X’-Y’-T- … Neutron Detector Array by CNS group

Summary

ü Neutron-rich Nuclei – Femto-scale Laboratory for Neutron Star Matter àEoS of Neutron-rich Nuclear Matter

p Collective Mode of Neutron-rich Nuclei à E1: PDR, GDR, E0: Breathing Mode CATANA has been completed à Togano-san’s talk Coulomb excitation of 50,52Ca for Pygmy Dipole Resonance: àSchedule fixed (Apr.8-14,2017) p Many-body correlations (super-fluidity, pairing, 4n correlation etc.)

• f very neutron-rich nuclei à Halo Nuclei

Coulomb breakup of 2n halo (22C, 19B) Radius of 22C: Y.Togano et al., PLB761, 412 (2016). Deformed driven halo, 31Ne, TN et al., PRL112,142501(2014). 37Mg, N.Kobayashi et al., PRL112, 242501(2014). 29Ne, N.Kobayashi et al., PRC 93, 014613 (2016). p Nuclear Force of very neutron-rich nuclei (and nn, nnnn correlations)à Tetra neutron K.Kisamori, S.Shimoura et al., PRL 116, 052501 (2016). 26O, barely unbound 2n states:

• Y. Kondo et al., PRL 116, 102503, (2016).

27,28O: Experiment Done This Talk

不安定核の物理

中村隆司著 （共立出版 2016年３月初版） 第１章 はじめに:原子核、不安定核、そして宇宙 第２章 原子核の限界 第３章 不安定核を作る 第４章 中性子ハロー 第５章 不安定核の殻進化ー魔法数の消失と出現 第６章 中性子過剰核で探る中性子星 第７章 結び– 不安定核物理の展望