M V Lomonosov Moscow State University D V

M. V. Lomonosov Moscow State University D. V. Scobeltsyn Institute of Nuclear Physics About the dependence of nuclear surface diffuseness on neutron-proton asymmetry and its influence on the evolution of single-particle spectra Bespalova O. V. , Klimochkina A. A. LXX International Conference "Nucleus-2020”

Nuclear surface near the drip lines “Skin”: an excess of neutrons (or protons) at the nuclear surface Halo-structure: diffuse cloud around the compact core, long tail of the density distribution 17 Ne neutron skin How does the diffuseness of the nuclear surface change when approaching to the drip lines? K. Tanaka, M. Fukuda, M. Mihara et al. Phys. Rev. C 82, 044309 (2010) 2 Nucleus-2020

How does the shape of the nuclear surface change near the drip lines? The diffuseness of the nuclear density distributions calculated within the HF+BCS model N. Antonov, D. N. Kadrev, M. K. Gaidarov et al. Phys. Rev. C 72, 044307 (2005) (N-Z)/A 3 an ap Nucleus-2020

The dispersive optical model • The dispersive optical model: Mahaux C. , Sartor R. “Single-Particle Motion in Nuclei”// Advances in Nuclear Physics. 1991. V. 20. P. 1 -224 • The dispersive optical model effectively takes into account the short range (distributed over the volume) and long range (concentrated at the surface) correlations • «The dispersive optical (model) provides a natural framework for data-driven extrapolations to the drip lines. » «…extrapolating the present DOM framework to more exotic nuclei will provide a benchmark for gauging the magnitude of any additional physics. » R. J. Charity et al. PRC C 76, 044314 (2007), C 83, 064605 (2011) • The dispersive optical model doesn’t demand high computing power 4 Nucleus-2020

Complex mean field of the dispersive optical model E>0 The traditional optical model. The imaginary part describes the ejection of an incident particle from the elastic channel. E<0 The imaginary part is associated with the existence of the mean free path of a nucleon in a bound single-particle state. It determines the lifetime of a nucleon in a bound state and the fragmentation width of this state. C. Mahaux et al. Dynamics of the shell model. Physics Reports. 120, (1985), 1— 274 5 Nucleus-2020

The dispersive optical model 6 Nucleus-2020

Global parameters of the traditional (nondispersive) optical model of the Koning-Delaroche KD A = 24— 209 E = 1 ke. V— 200 Me. V A. J. Koning, J. P. Delaroche. Local and global nucleon optical models from 1 ke. V to 200 Me. V. Nuclear Physics A 713 (2003) 231– 310 7 Depend on (N-Z)/A Don’t depend on (N-Z)/A VR , Wd r. V, d, a. V, d Nucleus-2020

The change of the proton level sequence: 2 s 1/2– 1 d 3/2 , Са isotopes 48 Са: 8 a. HF = a. VKD = 0. 659 fm 48 Са: a. HF = 0. 48 fm Nucleus-2020

The change of the proton level sequence: : 2 d 5/2– 1 g 7/2 , Sn isotopes 124 Sn: r. HF =1. 263 fm, a. HF =0. 583 fm (r. VKD = 1. 223 rm, a. VKD =0. 659 fm ) 9 Nucleus-2020

The charge density of 100, 132 Sn � 1) 2) As neutron excess increases: the radius of the charge density increases, BUT the extension of a surface decreases AND 3) the central charge density decreases As neutron excess increases, the proton density is pulled up following the neutron one. Protons from the center move closer to the periphery, increasing the radius of the charge density and decreasing its diffuseness. 10 Nucleus-2020

The dependence of the neutron 1 f 5/2 – 2 p gap on neutron excess 11 Nucleus-2020

The dependence of the neutron 1 f 5/2 – 2 p gap on r. HF and a. HF 12 Nucleus-2020

The effect of а. HF values on single-particle neutron energies Si a. HF = a. VKD 13 with A increase a. HF with (N-Z)/A increase Nucleus-2020

The dependence of the diffuseness a. HF on neutron excess + for n, – for р. - KD 14 Nucleus-2020

Thank you for your attention! M. V. Lomonosov Moscow State University D. V. Scobeltsyn Institute of Nuclear Physics 15 Nucleus-2020