Study the properties of fissionable heavy nuclei within the Generalized Liquid Drop Model 郭树青 指导老师：张鸿飞 兰州大学 The 13th National Nuclear Structure Conference of China, Chifeng

 Quasi-molecular shape  Generalized Liquid Drop Model(GLDM)  The most probable exit channals and corresponding half-lives;  Ellipsoid shape  Spontaneous fission barriers and half- lives Contents School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng

Quasi-molecular deformation School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng The one-body shape sequence is described within quasi- molecular shape sequence which allow to simulate the development of a deep neck in compact and little enlongated shapes with almost spherical ends.

Quasi-molecular defaormation School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng G.Royer and B.Remaud Nuclear Physics A444 (1985)477.

E GLDM =E vol +E surface +E Coulomb +E proximity +E shell +E pairing School of Nuclear Science and Technology,Lanzhou University Generalized Liquid Drop Model(GLDM) The 13th National Nuclear Structure Conference of China, Chifeng G.Royer and B.Remaud Nuclear Physics A444 (1985)477.

School of Nuclear Science and Technology,Lanzhou University Proximity Energy The 13th National Nuclear Structure Conference of China, Chifeng But the surface energy takes only into account the effects of the surface tension forces in a half space and does not include the contribution due to the attractive nuclear forces between the surfaces in regard in a neck or a gap between two separated fragments. Thus, an additional term called proximity energy must be added to take into account the nuclear interaction between opposite nucleons in a neck or a gap between fragments (~ - 40 MeV for heavy nuclei)

Shell Correction Deformed: Sphere: Deviation: School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng Myers W D.Droplet modelof atomic nuclei. Plenum,New-York,1977

Potential Barrier School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng

WKB method School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng

Exit channals U236

Half-lives

Ellipsoid shape School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng When one fragment is close to a magic spherical nucleus while the other one varies from spherical to prolate shapes. S>1:oblateS=1:sphericalS<1:prolate

Ellipsoid shape Surface enrgy: Columb energy: Interaction energy: School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng

Potential Barrier School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng Red:fragments are spherical Green:heavy(sphere) +light (ellipsoid) without shell correction(Royer) Black:heavy(sphere) +light (ellipsoid) with shell correction

Inner barrier The 13th National Nuclear Structure Conference of China, Chifeng School of Nuclear Science and Technology,Lanzhou University

Outer barrier The 13th National Nuclear Structure Conference of China, Chifeng School of Nuclear Science and Technology,Lanzhou University

Spontaneous fission half-lives School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng Z=92 Z=94 Z=96

Summary  The half-lives corresponding to the supposed most probable exit channals vary regularly for the expermental half-lives  Elliposoid shape introduced after the complement of the quasi-molecular deformation is resonable because of the proximity energy;  The GLDM taking into the ellipsoidal shape explains the inner and outer barriers very well. (< ) School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng

Problems  Shell correction is semiempirical,In large deformation around the two touching spherical fragments,new shell closures are formed.We add the shell correction simply;  The choice of the most probable fission path is difficult.They should be descrbed by the multi- dimensional potential surfaces. School of Nuclear Science and Technology,Lanzhou University The 13th National Nuclear Structure Conference of China, Chifeng

Thank you for your attention! The 13th National Nuclear Structure Conference of China, Chifeng School of Nuclear Science and Technology,Lanzhou University