Neutron removal reactions of 17C
Cuie Wu
School of Physics, Peking University
Cuie Wu et al., JPG31(2005)39
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1
Outline
Introduction
Experiment
Result and analysis
Summary
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1. Introduction
 Features of the drip-line nuclei
Short life, weak binding energy, halo, cluster structure, large
interaction and reaction cross sections, narrow momentum
distribution of the core, …
 Experiments
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1. Introduction
 Neutron removal (knockout) of the neutron-rich nuclei
P (c + n) + T  c + n + T
diffraction or elastic dissociation
c+X
stripping, or absorption, or inelastic dissociation
an excellent tool for getting spectroscopic
information about states in exotic nuclei,
such as the
Jπ of the ground state, the
E. Sauvan et al., Phys. Rev. C 69
(2004) 044603
spectroscopic factors for the halo states .
Z＝5～9，A＝12～25
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1. Introduction
 Neutron-rich Carbon isotopes
σR and σI
Sn and S2n
1600
R
Sn
30
I
1400
S2n
25
R or I (mb)
Separation Energy (MeV)
35
20
15
10
1200
1000
5
0
11
12
13
14
15
16
17
18
19
20
21
800
12
A
14
16
A
18
20
17C
17C
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Experimental setup (17C@79A MeV)
2. Experiment
F2 17C
RIPS @ RIKEN
16,15,14,…C F3
IC
D2
Reaction target
Bρ
F1
C
ΔE
TOF
D1
Bρ-TOF -ΔE
F0
A

Z
1
TOF 

Be
Primary beam
22Ne (110A MeV)
E 
Z
2
A
Z
After reaction target：
E 
Z2
2
TOF 
Z
SSD
Plastic
Z
1

E  A 
2
PPAC
E
TOF -ΔE - E
Bp 
Production target
ΔE
TOF
Particle identification
Before reaction target：
17C,...
NaI
A
2
Veto Plastic
2. Experiment
15C
16C
14C
TOF (ns)
17C
E (channel)
Particle identification at F3 with Z=6
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2. Experiment
17C
Counts
16C
15C
Target-in
Target-out
14C
E* (arbitrary)
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3.Result and analysis
Neutron removal cross sections
  xn

1 N 17 x  C
 
t
T  Nin

Summary of the experimental results for 17C + 12C at 79A MeV
Fragments
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Neutron removal cross sections (mb)
16C
 1n  116  18
15C
33
  2 n  70 18
14C
30
 3n  40 13
9
3.Result and analysis
 The few-body Glauber model analysis

I
The ground state is a superposition
of the configurations from all states.

c
 nlj

J
 The total one-neutron removal cross sections is,

Glauber
1n
   1n
I    C S I

2
c

c
, nlj  nlj , S 
sp
eff
n
nlj
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3.Result and analysis
The few-body Glauber model calculation
Main
component!
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3.Result and analysis
one neutron-removal cross section for 17C
200
Experiments:
Sauvan et al
Maddalena et al
present result
Cortina-Gil et al
150
Closed: C target
Open: Be target
Calculations:
100
Solid: C target
Dotted: Be target
50
100
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1000
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3.Result and analysis
The same few-body Glauber model predicts that if a nucleus
(AZ) consists of a core (A-1Z) and a halo (1n), then,
For 17C:
If we use the reaction cross sections of 17C
and 16C from [Cuie Wu et al., NPA739(2004)3] and [T.
Zheng et al., NPA709(2002)103], the right-hand side of
the above equation is 113±33 mb.
The present work gives:
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 1n  116  18mb
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4. Summary
Summary
 We measured the one-neutron removal cross section of 17C on 12C target
at 79A MeV. The σ-1n was analyzed within the framework of the fewbody Glauber model and a good agreement was found.
 The valence neutron of 17C is mainly in the d-orbital, which is in agreement
with the reaction cross section (C. Wu et al. NPA739(2004)3) and momentum
distribution measurements (V. Maddalena et al. PRC63(2001)024613).
 The calculation underestimate the data at higher energy while overestimate
the data at lower energy, the reason of which is yet to be understood.
 The two- and three-neutron removal cross sections are reported for the first
time but not analyzed by lack of a suitable theory. We hope the development
of the theory.
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Collaborators
Peking university, China
Yanlin Ye, Dongxing Jiang, Hui Hua,
Tao Zheng, Zhihuan Li
RIKEN, Japan
Y. Yamguchi, A. Ozawa, I. Tanihata
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