Transcript Coulomb Dissociation of 26Ne

Coulomb Dissociation of 26Ne
Nakamura-laboratory
Kazuhiro Ishikawa
02M01020
Contents
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Motivation
Introduction
Experimental Setup
Data Analysis
Results and Discussions
Conclusion
Motivation
Search for the Soft Dipole Resonance (SDR) in 26Ne
Breakup Coulomb Dissociation
Nuclear Breakup
Develop a method to distinguish two
components
Introduction
RIPS
Neutron-rich nuclei
Giant Dipole Resonance (GDR)
versus
Soft Dipole Resonance (SDR)
stable nuclei
E1 strength is almost exhausted by
Giant Dipole Resonance (GDR).
Ex=80A-1/3 MeV（～20 MeV 20Ne)
unstable nuclei
low lying E1 strength
Soft Dipole Resonance (SDR)
Prediction
Low Ex（ 8 MeV 26Ne)
In the case of 26Ne
Experimental Method
Coulomb Dissociation
Using High Z target
Calculated by equivalent photon method
Cross section = photon number × B(E1)
Experimental Setup
DALI
Experimental Setup
Reaction Target
Pb: Coulomb Dissociation
Al : Nuclear Breakup
Data Analysis
Silicon
Strip
Detector
Particle Identification Upstream of the Target
Pulse Height versus TOF
ΔE～Z2/v2=Z2TOF2
Particle Identification Downstream of the Target
ΔE=ΔEX＋ΔEY
Ekin=E+ΔE
ΔE=Z2/v2
Ekin=Av2/2
EkinΔE～AZ2
A: mass Z: charge
Mass Spectrum of Ne
Fragments
AZ2～ΔEE’kin=ΔE(E+ΔE/2)b (Z=10)
b=0.75
Removal of beam contaminants
Selecting of Angle(1~6 degree)
Neutron Tagged
Select specific mass
Reaction Cross Section
Angular Distribution
Results and Discussions
Neutron
Counter
Reaction Cross Section
Cross Section (mb)
Pb
Al
ε：εn~30%
Run
26Ne+p
b
25Ne 119(2)
26Ne+Al
10(0.3)
24Ne
211(3)
29(0.6)
23Ne
167(3)
22(0.5)
22Ne
197(3)
31(0.7)
Cross Section Ratio  (Pb)/  (Al)
Ratio for 25Ne is high!
1. Coulomb dissociation for 25Ne
2. Hindrance of σ (Al) for 25Ne ,
25Ne+Al→24Ne+n+x
σ pb (25)
σ Al (25)
 34% 
 56%
σ Al (24)
σ pb (24)
Angular Distribution of Ne Fragments
Al
Two components are seen.
Pb
Estimation of the width by the
fragmentation model
AP : Projectile mass
From Fermi motion Target Deflection A : Fragment mass
F
AF ( Ap  AF ) 2 AF ( AF  1) 2
EF : Fragment energy
2
 
0 
D
Ap  1
Ap ( A  1)
0 =87 MeV/c
d
EF 2
D =200~300 MeV/c
 C e xp( AF
)
d
2  2
p


σ⊥(MeV/c)
Al wide＋
Pb wide×
Al narrow＊
Pb narrow■
This result for wide is agreement with Goldhaber model.
Wide
Narrow
 D(Al)  D(Pb)
 D(Al)  D(Pb)
σ D(Al)  267(5)MeV/c
 D(Pb)  262(5)MeV/c
Conclusion
Electronics
 (Pb) /  (Al) for 25Ne
Large
Coulomb dissociation for the 26Ne+Pb→25Ne+n
reaction
Angular distributions
(narrow ,wide)
1.
2.
Two components
wide component : In agreement with
fragmentation model (nuclear component)
narrow component : Further investigations are
necessary (Coulomb component?)
Special thanks to
R332n Collaborators
Julien GibelinB, Koichi YoshidaE, Takashi NakamuraA, Dider BeaumelB, Nori AoiE
Hidetada BabaD, Yorick BlumefeldB, Zoltan ElekesE, Naoki FukudaE, Tomoko
GomiD, Yosuke KondoA, Akito SaitoD, Yositeru SatoA, Eri TakeshitaD, Satoshi
TakeuchiE, Takashi TeranisiC, Yasuhiro ToganoD, Victor LimaB, Yoshiyuki
YanagisawaE, Attukalathil Mayyan VinodkumarA, Toshiyuki KuboE, Tohru
MotobayashiE
A: Department of Physics. Tokyo Institute of Technology
B: Institut de Physique Nuclaire, Orsay, France
C: University of Tokyo (CNS), Riken Campus
D: Department of Physics, Rikkyo University
E: The Institute of Physics and Chemical Research (Riken)
Nakamura-laboratory
Takashi Sugimoto, Nobuyuki Matsui, Masako Ohara, Takumi Nakabayashi, Yoshiko
Hashimoto