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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
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