The 13th National Nuclear Structure Conference of China, Chifeng Fragments cross section distributions of even Ca at intermediate energy 马春旺 Outlook: 1. Backgrounds 2. The SAA Model 3. Results and Discussion 4. Conclusions 张艳芳, 魏慧玲 河南师范大学物理学系

The 13th National Nuclear Structure Conference of China, Chifeng 1. Backgrounds  Projectile fragmentation is one of the basic experimental method in RIB era. NSCL experiment: 40,48 Ca+ 9 Be/ 181 Ta, 58,64 Ni+ 9 Be/ 181 Ta, 86 Kr+ 9 Be  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.

The 13th National Nuclear Structure Conference of China, Chifeng 1. backgrounds– neutron skin thickness and EOS

The 13th National Nuclear Structure Conference of China, Chifeng 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

The 13th National Nuclear Structure Conference of China, Chifeng Chin. Phys. B 17(04)(2008)1674

The 13th National Nuclear Structure Conference of China, Chifeng 1.Backgrounds  Isospin dependence of PF 140A MeV 40,48 Ca/ 58,64 Ni+ 9 Be Ma Chun-Wang, et al., Chin. Phys. B18(11)(2009), to be published  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)

The 13th National Nuclear Structure Conference of China, Chifeng 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.

The 13th National Nuclear Structure Conference of China, Chifeng 2. The statistical 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

The 13th National Nuclear Structure Conference of China, Chifeng 2. The statistical abrasion-ablation (SAA) model The colliding nuclei: parallel tubes. transmission probabilities for neutrons (protons) at b: the average absorbed mass in an infinitesimal tubes at b Density distributions: Fermi-type Isotope production De-excitation Y.Eisenberg, PhysRev 52(1954)1378 Key for frag production

The 13th National Nuclear Structure Conference of China, Chifeng 3. Results

The 13th National Nuclear Structure Conference of China, Chifeng even Ca 3. PF of even Ca isotopes

The 13th National Nuclear Structure Conference of China, Chifeng 4. Results and discussion Isotonic distributions Isotopic distribution

The 13th National Nuclear Structure Conference of China, Chifeng Peak position (in A) as a function of ΔN, ΔZ

The 13th National Nuclear Structure Conference of China, Chifeng 4. Results and discussion

The 13th National Nuclear Structure Conference of China, Chifeng 4. Results and discussion Peak vs A fit results

The 13th National Nuclear Structure Conference of China, Chifeng 4. Results and discussion

The 13th National Nuclear Structure Conference of China, Chifeng 4. Results and discussion σ( i Ca)- σ( 40 Ca)

The 13th National Nuclear Structure Conference of China, Chifeng 5. Conclusion  The cross sections of fragments produced in 80 A MeV even Ca PF on 12 C were calculated by the SAA model.