Nuclear Physics at RIBF
1. Facility Overview
2. Nuclear structure & astrophysics
Highlights and on-going programs
3. Toward “Island-of-Stability”
4. Summary

H. Sakurai
RIKEN Nishina Center/Dept of Phys., Univ. of Tokyo

ＲＩ=Radioactive Isotope Ｂ=Beam Ｆ=Factory
Mass production of radioactive isotopes
as secondary beams
RIKEN
Wako Campus

Accelerator Facility Area

In-flight Production Method of RI beam
RI Production
via projectile fragmentation/fission

In-flight separator（magnet system tocollect and separate RIs）
Heavy Ion Accelerator

production target

RI beams
study of nucleifar from stability line
via secondary reactions

SRC

World’s First and Strongest
K2600MeVSuperconducting Ring Cyclotron

400 MeV/u Light-ion beam
345 MeV/u Uranium beam

BigRIPS

World’s Largest Acceptance
9 Tm
Superconducting RI beam Separator~250-300 MeV/nucleon RIB
K980-MeVIntermediate stage Ring Cyclotron (IRC)

Press-Conference on June 8th, 2010

T. Ohnishi et al., JPSJ 79, 073201 (2010)
D.Kameda et al., PRC 84 054319 (2012); 18 new isomers

Exploration of the Limit of Existence
stable nuclei
unstable nuclei observed so far
drip-lines (limit of existence)（theoretical predictions)magic numbers~300 nuclei~2700 nuclei~6000 nuclei

4000 species to be produced(1000 more new isotopes)
protons

New Element

113

278

04 July 23 18:55
57 fb

R-process path
Projectile Fragmentation
In-flight U fission & P.F.
78Ni ~0.1
particles/sec.(goal)(2007)
10 particles/sec.

byby 10pnA
1pmA 350 MeV/u U-beam
neutrons

Challenges at the RIBF
Shell Evolution :magicity loss and new magicity

R-process path: Synthesis up to UE(2+)

Mass number

EOS: asymmetric nuclear matterSN explosion, neutron-star,gravitational wave

Dynamics of new “material” :Neutron-skin（halo）
Density distribution

neutron skin
Neutron+proton

proton陽子・中性子
neutron一様物質

matterneutronsr

Exotic Quantum-System
on Nuclear ChartFission
Cluster-decay

Super Heavy
Element

ShapeCoexistence
Proton-decay
Exotic radiation

p-n pairing

Explosive nucleosynthesis
in universe

Two neutron correlation
BEC BCS cross-overNew magicof N=16
3NF

Multi-neutron halo

RIBF Theory ForumNew Experimental Devices of RIBF
To maximize the potentials of intense RI beams available at RIBF
for several 100 – 1000 species
Rare RI ring
ZeroDegree
massmass
half-life
2013excited states
deformationcharge radii
Funded 2012
2008matter radii
charge distribution
SLOWRI
IRC-to-RIPS BT
2012matterdistribution
gas-catcher
multi-use
EM moments
single particle states
astrophysical reactions
giant resonances
to be funded
being funded
exotic modes
SAMURAIHI collisions (EOS)
SCRITSHARAQ spectrometer
U Tokyo

2012-

2009-

2010- (e+RI in 2012)

SCRIT Electron Scattering Facility
Wakasugi et al.

Commissioning of ISOL and preparation of UCx target

2009 Facility constructions
2010 Tuning of accelerators
Installation of SCRIT2011 SCRIT performance test
ISOL commissioning
2012 Test of RI production
Tuning of ISOL
2013 Upgrade RTM
Construction e-Spectrometer
Full-scale RI production
Start Experiments for RI’s

Training oftarget production
238UO +C (disk) →2UCx (238U 30g)
Test withstable Xe isotopes
Mass resolution
M/DM 1660
Overall efficiency
21 %Test Experiments using Stable 133Cs
Achieved luminosity 1.8×1027 /(cm2s)
Ion trapping efficiency 85 %at 240 mA
Measurements ofElectrons elasticallyscattered fromtrapped Cs ionsin SCRITwith Cs
without Cs

“Rare RI Ring” for mass measurementConstruction started in April 2012!
Ozawa, Wakasugi, Uesaka et al.
Specialized to mass measurementsof r-process nuclei
Low production rate (~1/day)
Short life time (<50ms)

Key technologies:
Isochronous ring
ΔT/T < 10-6 for δp/p=±0.5%
Individual injection triggered bya detector at BigRIPS
efficiency ~ 100%even for a “cyclotron” beam

Schedule:
2014 Commissioning run
2015~ Mass measurements of RISAMURAI Spectrometer

Kobayashi et al 2012-versatile spectrometer with a large superconducting magnet

Spectroscopy ofUnbound States(p,2p)
Nucl. Astrophys. (p,g)
Clustering
3NF w/ pol. deuteron
EoS in HIC

Bending Magnet
Superconducting
Large B・L (7Tm)
Large pole gap (80cm)
Weight ~ 600 tonNeutron

March Commissioning
May B-19, C-22 etc.

d setup

TPC(not shown in picture) Proton
NSCL, Liverpool, TA&M joining this project

Heavy Ion

(not shownin picture)

Experimental Devices available at the new facility
SHARAQ(2009~) CNS-UTHigh resolution spectrometer
Miki et al., PRL 108, 262503 (2012)
IVSMR in Zr-90 and Pb-208 via (t,He3)

SAMURAI (2012~)

BigRIPS (2007~)
2nd

1stproduction targetZeroDegree (2008~)

K. Sekiguchi et al., PRC 83, 061001(2011)
3NF study in elastic pol.d + p scattering
For polarized deuteron only

SRCBigDpol(2009~)

Shell Evolution : In-beam gamma and decay spectroscopy
Decay
In-beamMagicity loss at N=82 ?
W. He, N. Aoi et al

New deformed magic N=64 in Zr
T. Sumikama et al., PRL 106, 202501 (2011)

Shape-isomer and Triaxiality at A~100
H. Watanabe et al., Phys.Lett.B 704,270-275(2011)
H. Watanabe et al., Phys.Lett.B 696,186-190(2011)

Double-magicity of Ni-78?
Island-of-inversion region
and beyond (N=20-28)

K. Yoneda et al

New magicity at N=34 in Ca?
D. Steppenbeck, S. Takeuchi et al.

Collectivity enhancement toward the drip line in Ne andDiscovery of deformed halo nucleus 31Ne
DayOne in 2008
“Island of inversion” region

Collectivity enhancement toward the drip line?
Doornenbal, Scheit et al. PRL 103, 032501 (2009)

32Ne28Ne

820345A MeV 48Ca beam
31Ne 10 pps/100pnA
32Ne 5 pps/100pnA

A large deformation at Z=10-12in spite of N=20
A pilot-region for nuclear structureInterplay of three ingredients:
Weakly-bound natures
Tensor forces
Pairing

722 keVA new candidate of halo nuclei: 31Ne
Large Coulomb breakup cross section Total X-section Jump at 29,,31Ne

Nakamura et al., PRL 103, 262501(2009)
Takechi, Otsubo et al., PLB707, 357 (2012)

Halo Structures of 29Ne and 31Ne
Ne+C

Takechi et al., Phys. Lett. B707, 357 (2012)

skin+def

StableA^1/3[330 1/2][200 1/2][321 3/2][200 1/2]Extension of the deformation region up to the drip-line
32Mg

2034Mg

RIBF

2034MgPeninsula!!

Island?
30Ne

832Mg

28
31FStability enhancement

30Ne

2831F

8

Stability enhancement

Doornenbal, Scheit, et al.
Ne-32 1st excited states: PRL 103, 032501 (2009)
New states in 31,32,33Na: PRC 81, 041305R (2010)
Mg-36,-38: ARIS11; in preparation
F-29: in preparation
Chevier, Ueno et al.,Intruder state in S-43: PRL 108, 162501 (2012)
Takeuchi et al.
Si-42 : PRL109, 182501 (2012)

Well developed deformation of 42Si
S. Takeuchi et al., PRL109, 182501 (2012)

Confirmation of 2+ energy observed at GANILHigh statistic data allows gamma-gamma
Coincidence
44S + C -> 42Si +X
Otsuka, Utsuno
E(4+)/E(2+)~3 for Si-42Nowaki, PovesCollectivity of the neutron-rich Mg isotopes
Excitation Energy of 2+ and 4+ in Mg

P. Doornenbal, et al. in preparation
AAl -> A-1Mg

For A=34 to 38
E(2+)~700 keV
E(4+)/E(2+)~3.1
At N=22, 24, 26 the nuclei
are well deformed
No increase of E(2+) at N=26
N=28 for Mg is not magic

N=20
N=20

2222

2424

2626

B(E2)?
Mn/Mp?
E(2+), E(4+) in 40Mg?
Energy of single particle states?

The First Decay Spectroscopy at RIBF
2009 Dec.
Sumikama, Nishimura, et al.
U beam to access A~110 region
Collectivity
triaxiality, shape-coexistence, etc
Intensity 0.8 pnA max.
0.1-0.2 pnA on average
2.5 days for data accumulation
STOP Detector( Decay experiment )Clovers (RIKEN)
LaBr3 (Milano)
9 layers of DSSD (RIKEN, TUS)

Exotic Collective-Motions at A~110 and
Their Applications to the R-process Nucleosynthesis
New Half-life data for
18 new isotopes
S. Nishimura et al.,PRL 106, 052502 (2011)
Deformed magic N=64in Zr isotopes
T. Sumikama et al.,PRL 106, 202501 (2011)

Low-lying level structure of Nb-109:
A possible oblate prolate shape isomer
H. Watanabe et al.,Phys. Lett. B 696, 186-190 (2011)

Development of axial
asymmetry in neutron-richnucleus Mo-110
H. Watanabe et al.,Phys.Lett.B 704,270-275(2011)

First “touch” for the r-process nuclei
T.Ohnishi, JPSJ 79 (2010).. 45 new isotopes

S. Nishimura et al.

B.Pfeiffer et al. Z. Phys. A357 (1997)

New half-lives (18 nuclei) are measured !

ZZ- Shell quenching?
- Shell quenching?

NNBrand-new half-life data for 18 isotopes
T1/2 unknown
R-process waiting points

8 hour data acquisition
T1/2 data of 38 isotopes including
first data for 18 isotopes
FRDM may underestimate Q-value
for Zr and Nb by 1 MeV at A~110
More rapid flow in the rapid
neutron-capture process
than expected

S. Nishimura et al., PRL 106 (11) 052502
1/3 ~ 1/2 Shorter Half-lives ofZr and Nb (A~110)

EURICAEUROBALL-RIKEN Cluster Array (EURICA) 2012-14
First decay spectroscopy in 2009

4 clovers
U beam ~0.1pnA
2.5 days MT4 papers

Total gain factor for gamma-ray statistics
at EURICA campaign in 2012-14 x1000
gamma efficiency x10
primary beam intensity x100
Approved MT 100 days
Estimation for number of papers expected~100 days * 4 papers/2.5 days= ~160
Cf. RHIC PHENIX ~100 papers/10years
2012 March Commissioning
June N=Z decay experiment

Perspectives of gamma-spectroscopy for next 5 years
Decay spectroscopy

In-beam gamma
Fast beams

E-degraded

Dali2 (RIKEN)
Grape (CNS)

2014+MINOS201XSHOGUNYear

4clovers
EURICA 2012-14

2014Clover-based ballUSA/RCNP/Tohoku U…
International Workshop
Dec. 7th -8th at RCNP,
Osaka Univ.

Pn with He-3

Intensity records and outlook
OHe

Max. beam power:
6.2 kW (18O – 345 MeV/u)

dNCaZnKrGoal for U beamXe

U

15pnA Nov., 2012

48Ca

70Zn

Kr

124Xe

238U

FY2012 plan

150 pnA-30 pnA

10 pnA

5 pnA

achieved(maximum)

415 pnA !

100 pnA !

‘30 pnA’

27 pnA!

3.8 pnA(Jun. 2012)(Jul. 2012)(Nov. 2007)(Jul. 2012)(Dec. 2011)

Kamigaito et al.

Two-step production of Spin-Aligned Rare Isotope Beams
Y.Ichikawa, H.Ueno et al., Nature Physics, on-line

Dispersion matching technique

RIKEN RI Beam Factory (RIBF)
Experiment facility

Old facility
RIPSGARIS

60~100 MeV/nucleon

SHE
Z=113

To be funded

Accelerator
SCRIT~5 MeV/nucleon

RILAC

AVF

ZeroDegree
SAMURAI

fRC

RRC

SRC

SLOWRI

IRC

CRIB (CNS)<10 MeV/nucleon

New facility

RI-ring

BigRIPS

SHARAQ (CNS)

350-400 MeV/nucleon

Intense (80 kW max.) H.I. beams (up to U) of 345AMeV at SRC
Fast RI beams by projectile fragmentation and U-fission at BigRIPS
Operation since 2007Element 113

K. Morita et al., J. Phys. Soc. Jpn. 81 (2012) 103201

Best Inventions of the Year 2012 | Element 113 | TIME.com$1 million - $2.5 billion
Element 113
Price: $3 million
By TIME Staff
Nov. 01, 2012
nishina.riken.jp
A time sequence of consecutive a-decays
from element 113

After nine years of work,a team led by Kosuke Morita at the RIKEN
Nishina Center for Accelerator-Based Sciencein Japan has created three atoms of the highly
unstable superheavy element 113.
As yet nameless, it has an enormous nucleus
containing 113 protons and 165 neutrons.

Challenge for the limit of existence
Island of stability Z=114, 120 N=184

GARIS

Nuclear reaction study
to find out path-ways
for production ofmore neutron-richand heavier nuclei

Termination of r-process
Projectile Fragmentation
In-flight U fission & P.F.

Neutron drip-line?

How to Create More N-rich and Heavier Nuclei ?
Low-E HI reactions with n-rich RI beams :Deep in-elastic collisions?
Fusion/Fission Processes?
Combination of projectile and target?

compound nucleus

Structure/Dynamics
in finite T and dilute system:
Role of neutrons in reactions/Fissions?
Clustering/Fission mechanism?
Isospin dependence of Fission?
dilute matter
Shell structure in hot nuclei?

RIBF Theory Forum

Excitation E

dilute n-matter

weakly-bounddilute system

unbound
Neutron-drip line

Stable nuclei

Neutron-drip line
RIBF Theory ForumNew Projects toward the island-of-stability
SHARAQ(2009~) CNS-UTNew Low-E Reaction BranchE-degraded RI beam line & spectrometer
Reaction and structure studies
with n-rich RI beams
1stSAMURAI (2012~)

production target

Clustering
FissionFor polarized deuteron onlySRC

Summary
RIBF has started in operation since 2007.
Mass and charge-distribution measurements are being prepared.
Bunch of data for shell evolution and nuclear astrophysics
are being produced via in-beam gamma spectroscopy
and decay spectroscopy
Spin-aligned beams will give big opportunities forelectro-magnetic moment and new types of reaction studies.
Primary beam intensity is increased year by year
to expand our play ground.

Toward the island-of-stability, new programs are being considered.