Reaction cross sections of carbon isotopes incident on proton and 12C

International Nuclear Physics Conference, Tokyo, Japan

June 3-8, 2007

W. Horiuchi (Niigata)

B. Abu-Ibrahim (Cairo), A. Kohama (RIKEN)

Y. Suzuki (Niigata)

Motivation• Reaction and interaction cross

sections have been measuredup to 20C on a 12C target.

• Analysis of 19,20,22C+p is in progress at RIKEN (QW-005).→　 Prediction of reaction cross sections of carbon isotopes.

A. Ozawa et al., Nucl. Phys. A693, 32(2001).

Contents

1. Reaction model: the Glauber theory.

2. Densities of C isotopes.

3. σR on a 12C target.

4. σR on a proton target.

5. Comparison of the two targets.

6. Summary

～900AMeV

Reaction model: Glauber theory

For a proton target

Reaction cross section:

Optical Limit Approximation

For a 12C target

Input: p and n density distribution.

Profile function.

NTG: OLA + higher order correction.

NTO: Eikonal Approx. with the global optical potential (N-12C).

Profile function:

p-12C and 12C-12C

Excellent agreement with experiment in a wide range energy.

Non-adjustable parameters.

p-12C reaction cross section

How to construct the densities

• Slater determinant generated from a mean field potential of Woods-Saxon form.

Potential strength → determined to reproduce Sn and Sp.

• To go beyond the mean field description.• A core+n model (core: A-1C) for odd nuclei.• A core+n+n three-body model for 16C and 22C.

– 16C: (1s1/2)(0d5/2) mixing (W.H., Y. Suzuki, PRC73,037304(2006), QM-064)

– 22C: Borromean (W.H., Y. Suzuki,PRC74, 034304(2006), QM-064)

Reaction cross sections of

carbon isotopeson a 12C

Good agreement with experiment at high energy except for 15,17C.

On a proton target

Reaction cross section of C+p

40MeV

Empirical S2n: 0.423±1.140 MeV

22C: 20C+n+n

3-body cal.

Proton vs 12C target

We define the quantity σR(b) as the same definition of the reaction cross section:

(upper limit of integral is limited to b)

Comparing the reaction cross section at low energy (40MeV) with that at high energy (800MeV).

proton

neutronmatter

σR(b)/σR of 22C

12C target

p target⊿b: 2.0fm

⊿b: 1.6fm

800AMeV

40AMeV

→　 A proton target is more sensitive for neutron distribution than a 12C target.

90%

90%

Summary• We have investigated reaction cross sections of carbon i

sotopes systematically in the Glauber model.– Even: densities constructed by a mean field model.– Odd: core+n model is used.– 22C: 20C+n+n three-body model.

• On a 12C (W.H., B. Abu-Ibrahim, Y. Suzuki, A. Kohama,PRC75, 044607(2007))

– 12C+12C reaction are reproduced very well. – Reaction cross sections of other isotopes are in reasonable agre

ement (except for 15,17C+12C reaction).

• On a proton (in preparation)– We predict reaction cross section of 22C.

960-1000 mb at 40MeV on a proton (very large A～ 60)

– p target is more advantageous than 12C target to probe extended neutron distribution.