Coulomb Breakup of Halo Nuclei
T. Nakamura
Tokyo Institute of Technology
Coulomb Breakup of 11Li1
Contents
T. Nakamura, A.M.Vinodkumar et al., Phys. Rev. Lett. 96, 252502 (2006)
2
3 SAMURAI/NEBULA Project at RIKEN RIBF
Inclusive Coulomb Breakup of 31Ne and 22C :
Dayone experiments at RIBF
0 Introduction
Introduction
•Soft Dipole Excitation
—Structureless E1 Continuum due to Halo Structure
Enhancement of E1 Strength at Low Excitation Energies
Ex
dB(E1)dEx
10~20MeV
GDR~1MeV Soft E1
Unique properties
for Neutron Halo Nuclei
Questions
• Nuclear Halo --- Universal?
• How is nuclear structure at the drip line characterized?
Coulomb Breakup
• One neutron halo
• Two neutron halo
How B(E1) can be related to halo structure?
Di-neutron Correlation?
Coulomb Breakup of 11Li 1
T. Nakamura, A.M.Vinodkumar et al.,
Phys. Rev. Lett. 96, 252502 (2006).
HHe
LiBeBC
NO
FNe
N=8
N=20
11Li 14Be
19C
17C
11Li
High-Z Target
(Pb)
9Li
ng
= NE1(Ex)dB(E1)dEx
dsCD
dEx 9hc
16p3
Cross section = (Photon Number)x(Transition Probability)
Invariant Mass
Equivalent Photon Method
relx , EE
)Li(),(),( 9PnPnP
11Li*
n
Coulomb Breakup
Examine Different Wall Events
t1
t2
b1
b2
b12
Condition: 121 bb Almost no bias
Elimination of Cross-Talk events
High detection sensitivity
even at Erel~0MeV (q~0)
q
11Li
NEUT
Wall 1
NEUT
Wall 2
Precise measurement
of B(E1) distribution of 11Li
Experimental Results
H.Esbensen and G.F. Bertsch
NPA542,310 (1992).
Comparison with
3-body Theory-1
Calculation
H.Esbensen et al.,
PRC76, 024302 (2007)
TN et al. PRL96,252502(2006).
W.u)6(5.4
)3MeV(18.042.1)1( rel
22
EfmeEB
Non-energy weighted
E1 Cluster Sum Rule
2
2
2
21
2
2
2
1
2
0
3
)(24
3)1()1(
nc
x
x
rA
Ze
rrrrA
ZedE
dE
EdBEB
p
p
r1
r2 n
9Li
rc-2n
fm32.001.5
)22(78.1
)3MeV(18.042.1)1(
2
2
22
rel
22
ncr
fme
EfmeEB
(Extrapolated value)
~70% larger than non-correlated
strength ( 021 rr
deg48 14
1812
q
n
Comparison with 3-body theory-2
Myo et al.,PRC76,024305 (2007).
Core polarization
(Tensor correlation+Pauli Principle)
P(S2)~ 40% fm38.52
2 ncr deg6512 q
Both Charge distribution & B(E1) are reproduced.
O(E1)|11Li(gs)>
?
9Li
n
n
2n Correlations can be studied by 3-body decay of 11Li*?
)(9 LiPcm
)(nPcm
)(nPcm
--Kinematically complete measurement
Experimental Result
E(9Li-n)
E(9
Li-n)
1M
eV
Further Correlation?E(9Li-n)
n
9Li
E(9Li-n)
1MeV
Simulation (Phase Space)
E(9Li-n)
n
34.2q
10Li s-wave
Virtual state
p-wave?
...)()()Li()Li(|)1(
...)()Li()()Li()Li(
1
2/1
1
2/1gs
9
gs
11
2
2/1gs
92
2/1gs
9
gs
11
psEO
ps
g
b
E(9Li-n)
E(9
Li-n)
34.2q
2 Inclusive Coulomb Breakup
of 31Ne and 22C
@ RIKEN RI BEAM FACTORY
As an experiment for
Day-one 48Ca beam campaign,
December 2008
ZDS
48Ca 345MeV/nucleon ~100pnA
SRC
BIGRIPSIRC
FRC
RRC
RIKEN RI Beam Factory (RIBF) Completed in 2007
World Largest RI-beam facility
HHe
LiBeBC
NO
FNe
NaMgAlSi
PS
ClAr
KCa
N=8N=2
Drip Line
11Li
11Be 19C
20C
22C 31Ne
Island of Inversion
48Ca
345MeV/u31Ne ~230MeV/u22,20,19C ~250MeV/u
Pb,C tgt
TOF Br, DE
Eth
x
x
xE dEdE
EdBEN
cE
)1()(
9
16)1( 1
3
ps
Inclusive Coulomb Breakup
31Ne+Pb30Ne+X22C+Pb20C+X
TOF,DEBr@ZDS
22C
19B17B
20C19C
23N22N
TOF (ns) (F3-F7) ~A/Z
DE
(F7PL)
3 SAMURAI / NEBULA PROJECT
@ RIKEN RI BEAM FACTORY
ZDS
48Ca 345MeV/nucleon ~100pnA
SRC
BIGRIPSIRC
FRC
RRC
RIKEN RI Beam Factory (RIBF)
SAMURAI
To let neutron(s) pass
through the gap
Sweep Beam and
Charged Fragments
Good Mass Resolution
for PID @ A~100
SAMURAISuperconducting Analyser for MUlti-particles from RAdio-Isotope Beam
Bending Power
BL=7Tm (B=3Tesla, 60deg bending)
2008-2011 1.5GJPY~16MUSD~13MEuro
+NEBULA(NEutron Detection
System for Breakup of
Unstable Nuclei with
Large Acceptance)
Superconducting
Magnet
126
8228
Physics of Neutron-rich Nuclei
via Breakup Reactions (@SAMURAI/NEBULA)
28
82
20
8
2
50
20
50
82
Giant Halos? 2n, 4n-correlation?
New Cluster/Molecular States?
States beyond drip-lines? (4n,28O, and more)
Drip-Line Physics
Structures and reactions
of r-process nucleiGiant and Pigmy resonances
of Neutron-skin nuclei
Neutron Star/Nuclear Matter
Summary
• Strong B(E1) at very low excitation energy
• neutron-neutron spatial correlation from E1 sum rule
qnn~50deg
•3body correlation in the decay of the dipole halo state
)keV300(18.042.1)1( 2
22 nSfmeEB
Coulomb Breakup of 11Li and two-neutron correlationT. Nakamura, A.M.Vinodkumar et al., Phys. Rev. Lett. 96, 252502 (2006).
1
3 SAMURAI/NEBULA Project
2 Inclusive Coulomb Breakup of 22C and 31Ne
Accumulated about ~1000 1n removal
events
Promising results
Collaborators
T.Nakamura, A.M.Vinodkuar, T.Sugimoto, Y.Kondo, N. Aoi, H. Baba, D. Bazin,
N. Fukuda, T. Gomi, H. Hasegawa, N. Imai, M. Ishihara, T.Kobayashi, T. Kubo,
M. Miura, T. Motobayashi, H. Otsu, A.Saito, H.Sakurai, S. Shimoura, K.
Watanabe, Y.X. Watanabe, T. Yakushiji, Y. Yanagisawa, K. Yoneda
Coulomb Breakup of 11Li ( PRL96,252502(2006))
Inclusive Coulomb Breakup of 31Ne and 22C as
an experiment in RIBF DayOne Campaign
T.Nakamura, N.Kobayashi(Duracell), Y.Satou, Y.Kondo, K.Tanaka, Y.Kawada,
N.Tanaka, S.Deguchi,N.Aoi,K.Yoneda,H.Baba, S.Takeuchi, T.Ohnishi,T.Kubo,
A.Saito, S.Shimoura, H.Sakurai, M.Ishihara, N.Orr, M.Takechi,T.Sumikama,
Y.Togano, E.Takeshita, H.Takeda,A.Yoshida,K.Yoshida,K.Kusaka,
Y.Yoshinaga,K.Miyashita
東工大物理GCOE 研究員募集中(1月27日締切)www.phys.titech.ac.jp を参照下さい。
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