RIBFでの核物理研究

櫻井博儀東大/理研

A

RI Beam Factory

2

“Exotic Nuclei”

“Super-Heavy Elements”Element 113th “Nihonium”

December 1st 2016

NhMass measurements

w/ MR-TOF coupled with

GARIS (KEK, Wada et al.)

In-flight method for production of Radioactive Isotope (RI) beam

Heavy Ion Accelerator（magnet system to collect and separate RIs）production target

study of nucleifar from stability linevia secondary reactions

In-flight separator

RI beams

before reaction

during reaction

after reaction

incident beam

RI beam

target nucleus

analyzing magnets

fragmentationor fission

Radioactive Isotope Beam Production and Delivery

World’s Largest Acceptance

High magnetic rigidity 9 Tm

Superconducting RI beam Separator

World’s First and Strongest

K2600MeV

Superconducting

Ring Cyclotron

target

RI Beam Production at BigRIPS Since 2007

O. Kamigaito et al.

194 new isotopes

(54 more to be confirmed)

x >3000

BigRIPS Team

Shell Evolution :

magicity loss and new magicity

E(2+)

Neutron Correlation in the

vicinity of the Drip-line

Mass number

R-process path: Synthesis up to U

EOS: asymmetric nuclear matter

SN explosion, neutron-star,

gravitational wave

6

Physics with Exotic Nuclei

Shell Evolution :

magicity loss and new magicity

E(2+)

Neutron Correlation in the

vicinity of the Drip-line

Mass number

R-process path: Synthesis up to U

EOS: asymmetric nuclear matter

SN explosion, neutron-star,

gravitational wave

7

Physics with Exotic Nuclei

~120 peer-reviewed papers from 2007 to 2018 (Aug.)

(References found in HS, Front. Phys. 13, 13211 (2018))

Shell Evolution :

magicity loss and new magicity

E(2+)

Neutron Correlation in the

vicinity of the Drip-line

Mass number

R-process path: Synthesis up to U

EOS: asymmetric nuclear matter

SN explosion, neutron-star,

gravitational wave

8

Physics with Exotic Nuclei

Shell Evolution

Nobel Prize 1963

Mayer & Jensen

2

8

20

28

50

82

126

Neutron-rich nucleiStable nuclei

N=16

?

?

?

?

loss

loss

Shell Structure

One-body potential

Large LS term

(surface contribution)

Magic numbers ->

2, 8, 20, 28, 50 …

R. Krucken

E(2+)

Magicity and its loss through determining E(2+)

828

20

28

50

82

82

50

126

[keV]Z

N

N=20-2832Ne:: Doornenbal, PRL 103, 032501 (2009) 36,38Mg: Doornenbal, PRL111, 212502 (2013)42Si : Takeuchi PRL109, 182501 (2012)40Mg : Crawford, PRL 122, 052501 (2019)

N=32, 3454Ca: Steppenbeck , Nature 502, 207 (2013)50Ar : Steppenbeck, PRL 114, 252501 (2015)52Ar: Liu, PRL 122, 072502 (2019)

N=5078Ni: Xu, PRL 113, 032505 (2014) 78Ni: Taniuchi, Nature 569, 53 (2019)

N=82, Z=50126Pd: Wang, PRC 88 054318 (2013)136Sn: Wang, PTEP 023D02 (2014)126,128Pd : Watanabe, PRL 111, 152501 (2013) 136,138Sn : Simpson, PRL113, 132502 (2014)

Shell EvolutionNew Magicityof N=34(2013)

Magicity Loss at N=20, 28New magic number N=34Double magicity of 78Ni（Z=28, N=50）Magicity at N=82 with Z>46…

In-beam gamma: SUNFLOWER

SEASTAR

Decay spectroscopy: EURICA

First spectroscopy of 40Mg, 52Ar and 78Ni

Mysterious structure in 40Mg

78Ni revealed as a doubly magic stronghold against nuclear deformationTaniuchi et al., Nature 569, 53 (2019)

Crawford et al., PRL 122, 052501 (2019)

40Mg

38Mg

36Mg4->2

?

Sudden change of the structure between 38Mg and 40Mg

40Mg has larger deformation than 38Mg.

Origin of the 2nd excited state is mystery.No theory reproduces the data.

2->0

Robustness of the N = 34 Subshell ClosureH.N. Liu et al., PRL 122, 072502 (2019)

E(2+) of 52Ar is higher than 50Ar !

N=28 N=34

13

Schedule:2018 Dec PAC construction proposal2019 April the 1st workshops in Darmstadt

60 participants, 38 LoI (~150 days) August the 2nd workshop in Osaka Dec PAC each proposal

2020 spring, fall physics run 45 days

HiCARI ProjectHigh Resolution Gamma-Ray Spectroscopy

RCNP+LBNL+Koeln+Darmstadt+Tokyo+RIKEN….

MINIBALL + Berkeley P3 triple +RCNP Quad + …

2% resolution, 10% for 1 MeV g

Organization:Spokesperson

Kathrin Wimmer (Madrid), Pieter DoornenbalSteering Committee

Nori Aoi (RCNP Osaka), Anna Corsi (CEA Saclay),Heather Crawford (LBNL Bereley)Andrea Jungclaus (CSIC Madrid)Thorsten Kroell (TU Darmstadt), Peter Reiter (U Koeln)Daisuke Suzuki (RIKEN Nishina Center)

Proton MagicityZ=50

Neutron MagicityN=82

Proton MagicityZ==28

Neutron MagicityN=50 Neutron number

Pro

ton

nu

mb

erEURICA Achievements

Half-lives

r-process path (prediction)

E(2+)

Indication of a double magic 78Ni Xu et al., PRL 113, 032505 (2014)

Z=28 78Ni

N=50

Half-lives for 110 n-rich nucleiLorusso et al., PRL 114, 192501 (2015)

Half-lives for 94 n-rich nucleiWu et al., PRL 118, 072701 (2017)

r-process path

rapid neutron-capture

vs beta-decay

Supernova explosion?

NS merger?

Or both?

N=50

N=82

N=126

The r-process

nucleosynthesis

known

William A. Fowler1983 Nobel Prize Physics

© The Nobel Foundation

1st peak

2nd peak

3rd peak

RIBF is measuring…

Mass -> path location

Half-life -> matter flow

Pn -> reaction network

Supernova? NS merger?

“Revolution” of the r-Process Research

G. Lorusso, S. Nishimura et al. Phys. Rev. Lett. 114, 192501 (2015)

Bunch of T1/2 data for n-rich nuclei at

Z=37-50 : 110 half-lives (40 new)

A standard model assuming (n,gamma)

equilibrium reproduces the r-abundance

up to rare-earth region

w/o new data

w/ new data

16

BRIKEN : β-Delayed Neutron Study 2017-

(sec)

N=8

2

N=

50

Systematics Study of Decay Properties (T1/2, Pn)

(1) (unexpected) trends → Nuclear structure(2) Study for r-process nucleosynthesis

S. Nishimura, A. Algora

NP1512-RIBF139

K. Rykaczewski, J. Tain,

R. Gryzywacz, I. Dillmann

NP1406-RIBF127R1

G. Lorusso, A. Estrade, F. Montes

NP1406-RIBF128

G. KissNP1612-RIBF148

Mass measurements at Rare-RI Ring

Yamaguchi (Saitama U.), Wakasugi (RIKEN), Uesaka (RIKEN), Ozawa (Tsukuba U.), et al.

Neutron shell gap

Proton shell gap

2002

2002

Key technologies:

Isochronous ring

ΔT/T < 10-6 for δp/p=±0.5%

Individual injection triggered by

a detector at BigRIPS

efficiency ~ 100%

even for a “cyclotron” beam

n-rich Ni and

n-rich N=82 running

in autumn 2018

The 1st Application for 75Cu spectroscopy

Disp.-match two-step PF method:

→ Large spin alignment A = 30(5)%

→ μ(75C 3/2–) measured

Discussion:

|𝟕𝟓𝐂𝐮⟩ = |𝟕𝟒𝐍𝐢(𝐜𝐨𝐫𝐫𝐞𝐜𝐭𝐞𝐝)⟩ ⊗ 𝒑

71Cu 75Cu73Cu69Cu

Y. Ichikawa et al., Nat. Phys. 15, 321 (2019)

Ichikawa et al.

Y. Ichikawa et al., Nat. Phys. 8, 918 (2012)

Neutron Correlation in the vicinity of the Drip-line

HHe

LiBeBC

NO

FNe

NaMgAlSi

PS

ClAr

K

N=8

N=16

N=20

N=28

2n halo known

4n halo/skin

1n halo known

Ca

Halo: low density nuclear (neutron) matter in the lab.

Multi-neutron correlation on and beyond the drip-line?

20

Deformed Halo Nuclei, Ne-31 and Mg-37, found at RIBF

31Ne

p-wave halo neutron

N

F

Na

Al

Ne

Mg

ONC

Z

16 20 28

Deformed

region

37Mg

31Ne

Inclusive Coulomb and Nuclear Breakup at

ZDS

37Mg

T.Nakamura et al., Phys.Rev.Lett.103,262501 (2009).

N.Kobayashi et al., PRC 86, 054604 (2012)

T.Nakamura,et al., Phys.Rev.Lett.112,142501 (2014).

N.Kobayashi et al., Phys. Rev. Lett. 112, 242501 (2014)

Total Interaction Cross Section at BigRIPSM. Takechi et al., Phys. Lett. B 707, 357 (2012)

M. Takechi et al., Phys. Rev. C 90, 061305(R) (2014)

Ca

HHe

LiBeBC

NO

FNe

NaMgAlSi

PS

ClAr

K

N=8

N=2

Day-One Campaign Experiments at SAMURAI:

Explore Neutron Drip Line (May 2012)

2n halo known

2n/4n halo(skin)?

1n-halo known

25O

• Established only up to Z=8 (O)

• Halo Structures

• New/Lost Magic Numbers

• Exotic Unbound Resonances

--- Physics at the bound limit

N=1622C19B

Coulomb Breakup of 19B and 22C, Nakamura et al.

26O

Study of 18B,21C, and excited states of 19B,22C, Orr et al.Structure of Unbound Oxygen Isotopes 25O,26O, Kondo et al.22

26O : Kondo et al., Phys. Rev. Lett. 116, 102503 (2016)22C : Togano et al., Phys. Lett. B 761, 412 (2016)19C : Hwang et al., Phys. Lett. B 769, 503 (2017)6He : Chebotaryov et al., PTEP 2018, 053D01 (2018)20,21B : Lebond et al., Phys. Rev. Lett. 121, 262502 (2018)

Towards establishment of Tetra-neutron

23

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

The first result from SHARAQ

This triggered extensive discussions:

Hiyama et al. No

(too strong 3N force is needed)

Shirokov et al. Yes

(NSCM with JISP16 interaction)

Gandolfi et al. Yes

(QMC with chiral interaction)

:

:

New Experiments to confirm its existence

・ New SHARAQ experiment 4He(8He,8Be) n4

being analyzed by S. Masuoka (JRA)

・ 8He(p,pα)n4 @SAMURAI

being analyzed by T. U. Darmstadt group

・ 8He(p,2p)7H→t+n4

being analyzed by Uesaka-g and LPC Caen

Equation of State in Asymmetric Nuclear Matter

Symmetric matter

Neutron matter

Symmetry energy

Direct reaction studies at normal density

Neutron-skin thickness (p,p) ESPRI +

(e,e) SCRIT

Landau-Migdal parameter (p,n)

Incompressiblity (d,d’) CAT(CNS Active Target) CNS/Notre Dame

Heavy-Ion collision

SπRIT @SAMURAI (RNC-Kyoto Univ.-MSU)

Basics in our understanding of

nucleon many-body system

Critical input to theory of neutron star,

supernovae, etc.

Density independent term is known

S(ρ=ρ0) ~ 32 MeV

Density dependence is focus of attention

24

SCRIT Facility for e+RI scattering

ERIS

SR2

Luminosity of 1027/(cm2s) was achieved at the e-beam current of 250mA.

Efficiency improvement

More high-power beam 10W->1kW

-> 1029/cm2/s

e-beamScattered

electrons

WiSES

First elastic scattering from 132XeTsukada et al., PRL118, 262501 (2017)

SpRIT Collaboration

SAMURAI Pion Reconstruction and Ion Tracker

SpRIT-Time Projection Chamber

53cm

E field

B field

x

y

NIMA 784 (2015) 513

26

GET electronics

The first campaign with fast RI beams !

April-June 2016

Journal of KPS 69-2 (2016) 144→Ph.D Thesis (Korea Univ.)

NIMA 853 (2017) 44→Ph.D Thesis (MSU)

NIMA 856 (2017) 92NIMA 887 (2018) 81NIMA 899 (2018) 43

Blue: Pi-

Red: Pi+

A

Facility upgrade in near future

“Exotic Nuclei”27

“SHE”RILAC upgrade (2019-)28GHz ECR

Super-conducting RF cavities

More intense beam for

SHE(119th and 120th)

Ca-Zn beams at SRC

New RF cavities

of RRC (2018)new cavities give higher voltages

at a low frequency of 18MHz

More intense U beams

at SRC

70 -> 200 pnA

Installation of Charge-Stripper Rings

(202X-)

U beams at SRC 200pnA -> 2pmA

18O

48Ca

70Zn

78Kr

124Xe

238U

–– 1 ppd (particle per day)

184

278113

120

Island of Stability

New magicity at N=90 ?

New magicity at N=58 ?

Magicity at N=50 ?

Fission properties

Termination of

r-process path？

The 3rd peak

Questions to be answered…

Magicity at N=126 ?

Magicity at N=82 ?

N=184？

Z=112-120？How to expand

the nuclear chart?

Low-energy reactions

with two-step method

High-energy reactions

with two-step method

29

High Excitation Energy and Spin States

Exotic Shape Condensation Structure at finite T

New setup for intense and low-E beams

30

OEDO+ “Spectrometer+Ge-array”For fast beams, intensity should be limited to 10^7/sec

For low-E beams, almost no limit at Coulomb barrier.

We do not have to identify beam, but have to identify

reaction products.

CNS+KEK+RCNP+RIKEN

(Spectrometer+Ge; not yet funded)

Shimoura et al.

Beam energy

Mass n

um

ber

Moved

in future

Shell Evolution

R-process path

Summary

OEDO is ready to go31

In-beam gamma spectroscopy

DALI2+ZD: first spectroscopy of 40MgSEASTAR : first spectroscopy of 78Ni

Robustness of N=34 in 52Ar HiCARI : High-resolution in 2020

Decay spectroscopyEURICA: Two proton radioactivity,

Shell gap etc

3rd Generation (00’s-20’s) High-Power Heavy-Ion Beams up to URIKEN/RIBFMSU/FRIB, IBS/RAON GSI/FAIR, IMP/HIAF

Bunch of T1/2 data with Z=55-67 at EURICA.The r-abundance up to rare-earth regioncould be reproduced with a standard modelincluding new half-life dataPn and mass measurements are ongoing at BRIKEN and Rare-RI Ring, respectively

FRIB FAIR

RAONHIAF

Intense and low-E RI beams