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Cuie Wu

School of Physics, Peking University

Neutron removal reactions of 17C

Cuie Wu et al., JPG31(2005)39

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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 interac

tion and reaction cross sections, narrow momentum distribution of

the core, …

Experiments

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an excellent tool for getting spectroscopic i

nformation about states in exotic nuclei, su

ch as the Jπ of the ground state, the spectro

scopic factors for the halo states .

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

E. Sauvan et al., Phys. Rev. C 69 (2004) 044603

Z ＝ 5 ～ 9 ， A ＝ 12 ～ 25

1. Introduction

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Neutron-rich Carbon isotopes

Sn and S2n

17C

σR and σI

17C

1. Introduction

Reaction targetC

F2 F3

Primary beam22Ne (110A MeV)

Production targetBe

D2

BρF1

ΔE

TOF TOF ΔE

PPAC PlasticSSD Veto Plastic

Experimental setup (17C@79A MeV)

F0

E

NaIIC

D1

16,15,14,…C17C

17C,...

RIPS @ RIKEN

Particle identificationBefore reaction target ： Bρ-TOF -ΔE

Z

ABp

1

TOF

2

2

Z

E

AZ

Z

After reaction target ： TOF -ΔE - E

2 AE

1

TOF

2

2

Z

E Z

A

2. Experiment

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E (channel)

14C15C

16C

17C

Particle identification at F3 with Z=6

TO

F (

ns)

2. Experiment

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E* (arbitrary)

Cou

nts

16C

14C15C

17C

Target-in

Target-out

2. Experiment

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in

x

xn NT

N

t

C1 17

Neutron removal cross sections

Summary of the experimental results for 17C + 12C at 79A MeV

16C

15C

14C

Fragments Neutron removal cross sections (mb)

30133 40

n

181161 n

3.Result and analysis

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The ground state is a superposition

of the configurations from all states. J

c nljI

The few-body Glauber model analysis

3.Result and analysis

The total one-neutron removal cross sections is,

effnsp

nljccn

Glaubern SnljnljISCI , ,2

11

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The few-body Glauber model calculation

Main component!

3.Result and analysis

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one neutron-removal cross section for 17C

Closed: C target

Open: Be target

Experiments:

Calculations:

Solid: C target

Dotted: Be target

3.Result and analysis

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The same few-body Glauber model predicts that if a nucleus (AZ) consists of a core (A-1Z) and a halo (1n), then,

The present work gives:

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.

mb181161 n

3.Result and analysis

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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 few-bod

y Glauber model and a good agreement was found.

The valence neutron of 17C is mainly in the d-orbital, which is in agreement w

ith the reaction cross section (C. Wu et al. NPA739(2004)3) and momentum di

stribution 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.

Summary

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.

4. Summary

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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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