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Chun-Wang Ma Department of Physics, Henan Normal University Email: machunwang@126

Isospin effect in the projectile fragmentation of calcium isotopes and a possible experimental observable?. Chun-Wang Ma Department of Physics, Henan Normal University Email: machunwang@126.com. Outlook:. 1. Backgrounds 2. The SAA Model 3. PF of calcium isotopes 4. Results and Discussion

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Chun-Wang Ma Department of Physics, Henan Normal University Email: machunwang@126

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  1. Isospin effect in the projectile fragmentation of calcium isotopesand a possible experimental observable? Chun-Wang Ma Department of Physics, Henan Normal University Email: machunwang@126.com Outlook: • 1. Backgrounds • 2. The SAA Model • 3. PF of calcium isotopes • 4. Results and Discussion • 5. Conclusions

  2. 1. Backgrounds • Projectile fragmentation is one of the basic experimental method in RIB era. • NSCL experiment: 40,48Ca+9Be/181Ta, 58,64Ni+9Be/181Ta, 86Kr+9Be • New generation or updated RIB facilities expand the nuclear chart to more neutron-rich and proton-rich sides. • Increasing interests in EOS of asymmetric nuclear matter: n-rich nuclei • Hotter in the research of ISOSPIN physics. • Neutron density distribution of neutron-rich nucleus hard to be extracted or measured. • Neutron skin thickness important in nuclear phys. etc.

  3. 1. backgrounds– neutron skin thickness and EOS

  4. 1. Backgrounds • Neutron density distribution or neutron skin thickness of asymmetric nuclear matter: not easy to know but important in nuclear physics. • Isospin phenomena are strongly related to the different proton and neutron density distribution of asymmetric nucleus. • Can the isospin phenomena be used to extract neutron density distribution of neutron skin thickness directly? The observable! D.Q.Fang, et al., PhysRevC61(2000)044610;Ma Chun-Wang, et al., Chin.Phys.B,17(2008)1216; Ma Chun-Wang, et al., Phys.Rev.C79(2009)034606,Chin. Phys. B18(11)(2009), to be published

  5. Chin. Phys. B 17(04)(2008)1674

  6. Backgrounds • Isospin dependence of PF 140A MeV 40,48Ca/ 58,64Ni+9Be • Isospin effect in fragments production and it’s decrease • Obvious in the productions of peripheral reactions. (big difference of proton and neutron density distribution in the surface of nucleus) • Decrease and disappear in the productions of central collisions. (similar proton and neutron density distributions in the core of nucleus) Ma Chun-Wang, et al., Chin. Phys. B18(11)(2009), to be published

  7. 1. Backgrounds • How do the peak position of the fragments distributions change in the PF of a series of isotopes? • If there are some parameters or observables that are related to neutron skin thickness? Find the correlation between neutron skin thickness and some observables.

  8. 2. Thestatistical abrasion-ablation (SAA)model • Brohm & Schmidt, Fang, Zhong, etc, • Simple and useful; • 2-steps reactions: • Collisions—participant and spectator • De-excitation Refs:NPA569(1994)821, PRC61(2000)044610, CPC 27(2003)39, EPJA10(2001)381,PRC79(2009)034606

  9. Key for frag production 2. Thestatistical abrasion-ablation (SAA)model The colliding nuclei: parallel tubes. Isotope production De-excitation transmission probabilities for neutrons (protons) atb: the average absorbed mass in an infinitesimal tubes at b Density distributions: Fermi-type Y.Eisenberg, PhysRev 52(1954)1378

  10. 3. PF of odd 36-52Ca isotopes • Fragments productions of 80A MeV 36-52Ca+12C reactions Plateau and its drop Disappearance of the isospin effect: the overlap of the fragment cross section distributions

  11. 4. Results and discussion • Fit these isotopic distributions by Gaussian function • Peak positions • Widths Good linear correlation: pk Vs. Zfrag preliminary • Fit the linear correlations between pk position and Zfrag • Slope (b) • Intercept (a)

  12. 4. Results and discussion • correlations between slope b and binding energy, b and Nproj preliminary

  13. 4. Results and discussion • Correlation between b and Sn-Sp: preliminary

  14. 4. Results and discussion • Correlation between b and neutron skin thickness Good linear correlation: preliminary

  15. 4. Results and discussion preliminary

  16. 5. Conclusion • The cross sections of fragments produced in 80 A MeV even 36-52Ca PF on 12C were calculated by the SAA model. • The fragments isotopic cross section distributions were fitted by Gaussian function, peak positions were obtained. • The Apk have good linear correlation to the Zfrag. The linear correlation were fitted and slopes b were obtained. • The correlation betweenb and Nproj., Sn, Sn-Sp, δnpwere analyzed. • Good linear correlation between b and δnp are found. • Still a question: b possible to serve as an observable for neutron skin thickness?

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