Transcript The RI-Beam Factory and

The RI-Beam Factory
and
Recent Development in
Superheavy Elements Search at
RIKEN
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Brief introduction to the RI Beam Factory
Confirmation of 271[110] and discovery of a
new transuranium isotope 234Bk
CNS summer school 2002
Isao Tanihata RIKEN
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RIBF is a multi-disciplinary facility
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Nuclear Physics
Nuclear Astrophysics
Atomic Physics
Material Science
Nuclear Chemistry
Biology
Medicine
Nuclear Power
CNS summer school 2002
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Nuclear Physics
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Probe the limit of nuclear existence and to
understand the basic physics of the nuclear
landscape
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Exploration of the limit of existence
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Magic numbers far from the stability
Study of unbalanced nuclear matter and the role of isospin
Explore the new forms and dynamics of nuclei
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Neutron skins & halos
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Drip-line nuclei
Nuclei outside the drip lines
Superheavy nuclei
Also excitations and correlation
Exotic shapes
Testing of the Standard model and fundamental
symmetries and conservation laws
CNS summer school 2002
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Nuclear Astrophysics
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Provide the basic data of nuclear astrophysics
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Big bang nucleosynthesis
The CNO cycle to the rp-process
Alpha-rich freeze out
The r-process
Equation of state of asymmetric matter and neutron stars
Highly ionized atoms of unstable nuclei
Remarks
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The measurement and the analysis of the nuclei far from stability will provide
new test benches for theoretical nuclear models. This should allow one to
reformulate these models in a more general form. Hence, the predictive power
of these models, when applied to unknown nuclei for nuclear astrophysics
applications, will be greatly increased.
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Bird Eye View of RIBF
2005
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The Beam Delivering Method
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AVF cyclotron --> will become free
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CNS summer school 2002
CNS/RIKEN
Present facility --> primary and
secondary beam from ISR
BigRIPS --> two experimental beam
lines
MUSES --> ACR, DSR
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Accelerator Scheme
Accelerators
ECR18
RILAC
RFQ linac
CMS
RRC
fRC
IRC
SRC
CNS summer school 2002
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Primary Beam Energy @RIBF
With fRC
1 pµA
for all elements
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IRC Sector magnet
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SRC design
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ECRIS-18
ECRIS-18
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ECRIS-18 Beam Intensity
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RI Beam Separators (Big-RIPS)
second stage separation and tagging
first stage separation
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Production Target
Target
Beam Sp ot
Be a m
Rotating
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Targ e
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Fixing
(Al) e
Plat
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Cooling
Plate (Al)
Cooling Water
(2 9 3 K)
in
Vacuum
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2
CNS summer school 2002
1
0
size unit
[mm]
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R.T. Test Result
CNS summer school 2002
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Rotating Target Extension
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Changing target thickness in one rotation
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6000 rpm -> 1 rotation = 10 ms -> 10˚=0.27 ms
Control of 0.3 ms is possible!
3mm/30cm diameter= 0.57
time
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D
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B
C
D
x at F1
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Experimental Room
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Secondary Beam Intensities
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Doubly Magic Nuclei Intensity
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Search for Superheavy Elements
Confirmation in different laboratories is essential!
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Advantage of RIKEN
Yield = s x T x I x e
s = 10-36cm2 (1pb)
T = 5x1017/cm2
I = 6x1012 /s (1 particle mA)
e = 0.3
Y = 9x10-7 events/s
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Heavy Element Search
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High-intensity beam from high-performance accelerator
High-performance recoil separator
Accelerator complex in RIKEN
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2.3 /month
ECR ion source + RFQ Linac + RILAC + CSM
Highest Energy
5.8AMeV
Highest Intensity
10 particle mA
Gas-filled Recoil Separator GARIS
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Velocity & Charge -state focusing
A large acceptance
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284. WE-Heraeus-Seminar 2002/08/08
ECR+RFQ+RILAC + CSM
GARIS
Ring Cyclotron
ECR ion source
CSM(Charge State Multiplier)
RILAC(RIken Linear ACcelerator)
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GARIS
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GARIS target with Beam
Target and Beam in He gas
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Vacuum
gas
Principle of GARIS
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Magnetic rigidity
R  mv/  q 
 q  v
mv0
R
0.62Z 1/ 3
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is independent from
the velocity of a nucleus.
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GARIS Detector
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271[110] by 208Pb(64Ni,n)271[110]
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271[110]
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Summary
Reaction
Target 208Pb
Efficiency
Counting rate of PSD
208Pb(64Ni,1n)271[110]
Beam energy
Total beam dose
Event number
Cross section
311.2 MeV
8.8x1017
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2.3
pb
Beam energy
Total beam dose
Event number
Cross section
314.2 MeV
6.3x1017
2
6.3
pb
T(1/2) =
12.9
230 mg/cm2
0.76
2/s (@ 0.4 pmA)
ms
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Collaborators:
K. Morita
RIKEN
K. Morimoto
RIKEN
D. Kaji
RIKEN, Niigata U.
And many others
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New Isotope of Bk
◆ 197Au(40Ar,3n)234Bk
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Beam energy at 196.9 and 188.4 MeV
1.5~2.5 particle µA
9 a-chain events have been observed.
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234Bk
a chains
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Decay chain of 234Bk
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Comparison of a-decay Q-value
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KUTY is the mass formula
with shell energies on a
spherical-basis,
TUYY is the mass formula
with an empirical shell term,
FRDM is the finite-rangedroplet model and foldedYukawa single-particle
potential, and
HFBCS is to be based on
the Hartree-Fock+BCS
method with the MSk7
Skyrmeforce.
Alpha decay Q-value Comparison
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1.5
Q-value difference from experimental
value
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1
0.5
0
Bk
Cm
Pu
U
Th
Ra
Rn
-0.5
-1
-1.5
elements
DKUTY
CNS summer school 2002
DTUYY
DFRDM
DHFBCS
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SHE search is running at full speed
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