The RIKEN RI Beam Factory- Its Scientific Programs -

H. Sakurai RIKEN Nishina Center/ Univ. of Tokyo

1. What is the RIBF ?2. Nuclear Physics Programs Spectroscopy on neutron-rich nuclei SHE3. Summary

RIPS GARIS60~100 MeV/nucleon

~5 MeV/nucleon

350-400 MeV/nucleon

Old facility

New facility

RIKEN RI Beam Factory (RIBF)

BigRIPS

SRC

RILAC

AVF

RRCfRC

IRC

Experiment facility

Accelerator

SHARAQ (CNS)

SAMURAIZeroDegree

SLOWRI

SCRIT

RI-ring

SHE Z=113

Intense (80 kW max.) H.I. beams (up to U) of 345AMeV at SRCFast RI beams by projectile fragmentation and U-fission at BigRIPSOperation since 2007

To be funded

<10 MeV/nucleon

CRIB (CNS)

K980-MeV Intermediate stage Ring Cyclotron (IRC)

World’s First and StrongestK2600MeVSuperconducting Ring Cyclotron

World’s Largest Acceptance9 TmSuperconducting RI beam Separator

400 MeV/u Light-ion beam345 MeV/u Uranium beam

SRC

BigRIPS

~250-300 MeV/nucleon RIB

8300 tons

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

U-238 Acceleration at Super-Conducting Cyclotron

U-238 beam

Be productiontarget

Setup to search fornew n-rich isotopes

new isotopes

Z, A/Q

to identify RI beams

event-by-event

Projectile Fragmentation

In-flight U fission & P.F.

prot

ons

neutrons

New Element27811304 July 23 18:5557 fb

Exploration of the Limit of Existencestable nuclei ~300 nucleiunstable nuclei observed so far ~2700 nucleidrip-lines (limit of existence) （ theoretical predictions) ~6000 nucleimagic numbers

R-process path

Nuclear Physics

Shell Evolution : magicity loss and new magicityShape ?Shell gap ?Cluster formation?Role of 3NF ?Magicity loss ?　　 50, 82, 126, …

Liberation from Stable Region and Emergence of Exotic Nuclei (1)

Skin thickness? Density distribution?Skin structure ? di-neutrons? p-n?Exotic collective modes of skin ？

Density distribution

陽子・中性子一様物質

r

Neutron+proton

neutrons

Spherical Deformed

neutron skin

proton-neutronmatter

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

E(2+)

Liberation from Stable Region and Emergence of Exotic Nuclei (2)

R-process path: Synthesis up to U

Necessary of experimental investigation for nuclear properties of heavy and neutron-rich nucleiMass, life-time, decay mode

EOS: Asymmetric nuclear matterSN explosion, neutron-star, gravity wave

Mean field +Dilute system : BEC-BCS cross over ?High density : 3NF, especially for T=3/2 ?

masshalf-lifeexcited statesdeformationcharge radiimatter radiicharge distributionmatter distributionEM momentssingle particle statesastrophysical reactionsgiant resonancesexotic modesHI collisions (EOS)

IRC-to-RIPS BTSLOWRI

SHARAQ spectrometer

SAMURAI SCRIT

Rare RI ring

U Tokyo

New Experimental Devices of RIBF

for several 100 – 1000 species

2008-

2009-

2012- e+RI (Sn-132) 2013-

Funded in 2012, Ni-78 2015-

ZeroDegree

Funded 2013!! being funded

To maximize the potentials of intense RI beams available at RIBF

gas-catcher

mass

multi-use 2012-

PID for ejectiles

High resolution

Large acceptance

SCRIT Electron Scattering Facility

2009 Facility constructions2010 Tuning of accelerators Installation of SCRIT2011 SCRIT performance test ISOL commissioning2012 Test of RI production Tuning of ISOL2013 Upgrade RTM Construction e-Spectrometer Full-scale RI production Start Experiments for RI’s

Wakasugi et al.

Achieved luminosity 1.8×1027 /(cm2s)Ion trapping efficiency 85 %at 240 mA

Commissioning of ISOL and preparation of UCx target

Test Experiments using Stable 133Cs

Test with stable Xe isotopesMass resolution M/M 1660Overall efficiency 21 %

Training of target production238UO2+C (disk) → UCx (238U 30g)

Measurements of Electrons elastically scattered fromtrapped Cs ions in SCRIT

with Cswithout Cs

“Rare RI Ring” for mass measurement

Construction started in April 2012!Ozawa, Wakasugi, Uesaka et al.

Specialized to mass measurements of 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 by a detector at BigRIPS efficiency ~ 100%

even for a “cyclotron” beam Schedule: 2014 Commissioning run 2015~ Mass measurements of RI

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

Neutron

ProtonHeavy Ion

TPC(not shown in picture)

Spectroscopy of Unbound States e.g. (,n) (p,2p) Missing Mass Nucl. Astrophys. (p,) Deuteron expts for 3NF Nucl. Matter

d setup(not shown in picture)

15M$ covers SC-Magnet 9M$ Detectors neutron counter electronics, software STQ for BT

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

IBS, Korea U, SNU, Hoseo U Joining the project

Commissioning Experiment March 2012

Experimental Devices available at the new facility

High resolution spectrometervia dispersion matching mode

SHARAQ(2009~) CNS-UT

ZeroDegree (2008~)SAMURAI (2012~)Versatile spectrometerwith a large superconducting magnet

Multi-function BT line

Spectroscopy w/ reactionsDecay spectroscopy

SRC

BigRIPS

Three Spectrometers at RIBF

Ca-48 Acceleration at Super-Conducting Cyclotron

Ca-48 beam

Be productiontarget

To deliver intense RI beams

PID for RI beams

Spectroscopy via reactions in the case of in-beam gamma

Secondary targetGamma-detectors to measure de-excited gamma rays

PID at ZeroDegree

20

8

28

34Mg

30Ne

32Mg

31FStability enhancement

20

8

28

34Mg

30Ne

32Mg

31FStability 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; PRL, in pressF-29: in preparationTakeuchi et al.Si-42 : PRL109, 182501 (2012)

Island? Peninsula!!

Magicity loss at N=20 and N=28

RIBF

N=28 magicity might belost in the Mg and Si nuclei.

Mechanism of large deformation?

New “Magicity” of N=34 in the Ca isotopes

D. Steppenbeck et al., Nature

Zn-70 -> Ti-56, Sc-55Ti-56, Sc-55 + Be -> Ca-54 + X

Zn-70 primary beam (100 pnA max)Ti-56 120 pps/pnA, Sc-55 12 pps/pnA

U-238 Acceleration at Super-Conducting Cyclotron

U-238 beam

Be productiontarget

Particle Identification ofRI beams

Super-conductin

g Inflight

Separator to deliver in

tense

RI beams

Decay Spectroscopy SetupBeta-delayed gamma -> Ge detectors HI implanted and beta-rays -> active stopper (DSSSD)

1st decay spectroscopy 2009 Dec.U beam intensity 0.1-0.2 pnA on average2.5 days for data accumulation

Exotic Collective-Motions at A~110 andTheir Applications to the R-process Nucleosynthesis

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

New Half-life data for18 new isotopesS. Nishimura et al., PRL 106, 052502 (2011)

Deformed magic N=64 in Zr isotopesT. Sumikama et al., PRL 106, 202501 (2011)

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

EURICA Project at RIBF

RIKEN RIBF(Japan)

Euroball Cluster detectorsSupport structure Readout electronicsused for GSI-RISING 2011 Nov.

EUROBALL-RIKEN Cluster Array (EURICA) 2012-14

First decay spectroscopy in 2009

Gain Factors from 2009 to 2012-14 for Decay Spectroscopy

U-beam intensity … x 50 times - 0.2 pnA 10 pnA

Gamma-ray efficiency … x 10 times - 4 Clover detectors (Det. Effi. ~1.5% at 0.662 MeV) 12 Cluster detectors (Det. Eff. ~ 15 % at 0.662MeV) Beam time x 40 times - 2.5 days (4 papers) 100 days … (160 papers)

EURICA setup

EUroball-RIKEN Cluster Array

Ca

Zn

Kr Xe

U

He O

N

d

Intensity records and outlook

Goal for U beam

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

Kamigaito et al.

15pnA Nov., 2012

SRC

IRC

RILAC

RRC

fRC

AVF

New Injector RILAC2to deliver more intense beam and more opportunities for SHE

GARIS (SHE)

BigRIPS (RIBF)

New Injector

300 days per year for SHE!!

RILAC2+28GHz SC-ECRIS

He gas stripper

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

Element 113

Summary

RIBF has started in operation since 2007.

Primary beam intensity is increased year by yearto expand our play ground.

All of experimental devices proposed have been fundedto give a diversity of experimental programs.

Bunch of data for shell evolution and nuclear astrophysics are being produced via in-beam gamma spectroscopy and decay spectroscopy.

Element 113th has been clearly identified.

ＲＩ =Radioactive Isotope Ｂ =Beam Ｆ=FactoryHeavy Ion Accelerator Facility dedicated to mass production of radioactive isotopes as secondary beams (since 2007)

Accelerator Facility Area

RIKENWako Campus

The First Decay Spectroscopy at RIBF

Sumikama, Nishimura, et al.2009 Dec. U beam to access A~110 region Collectivity triaxiality, shape-coexistence, R-process, etc. Intensity 0.8 pnA max. 0.1-0.2 pnA on average 2.5 days for data accumulation

Clovers (RIKEN)LaBr3 (Milano)9 layers of DSSD (RIKEN, TUM)

STOP Detector ( Decay experiment )

In-flight Production Method of RI beam

Heavy Ion Accelerator

（ magnet system to collect and separate RIs ）

RI Productionvia projectile fragmentation/fission

production target

study of nucleifar from stability linevia secondary reactionsand decay spectroscopy

In-flight separator

RI beams

Physics-basedFast separation400ns

projectiletarget

RI beam

Before reaction

During reaction

After reaction

magnets