Семинар по ядерной физике низких энергий

Дата и время: пятница, 3 июля 2020 г., в 14:30

Место: Онлайн конференция в Zoom, Лаборатория теоретической физики им. Н.Н. Боголюбова

Тема семинара: «Soft dipole mode in two-neutron halo nuclei and astrophysical 2n capture»

Авторы: Л. В. Григоренко^1,2,3, Н. Б. Шульгина^3,4, М. В. Жуков⁵

1 — Лаборатория ядерных реакций им. Г. Н. Флерова, ОИЯИ
2 — НИЯУ МИФИ, Москва, Россия
3 — НИЦ “Курчатовский институт”, Москва, Россия
4 — Лаборатория теоретической физики им. Н. Н. Боголюбова, ОИЯИ
5 — Кафедра физики, Технический университет Чалмерса, Гётеборг, Швеция

Докладчик: Н. Б. Шульгина

Аннотация:

The “soft dipole” E1 strength function is calculated for the transition from the ⁶He 0⁺ ground state to the 1^— continuum ⁴He+n+n. The calculations were performed within the hyperspherical harmonics formalism. The sensitivity of the results to the ⁶He ground state structure and to final state interactions, are analyzed. The large-basis calculations show the reliably converged results for soft dipole strength function and for momentum correlations of the ⁶He → ⁴He+n+n dissociation products. Transition mechanisms are analyzed based on the momentum correlations. The comparison with experimental data is provided. The low energy behavior of the strength function, which is important for astrophysics, was specially stressed. Use of exceptionally large basis sizes and well-grounded extrapolation procedures allows to move to energies as small as 1 keV. It is found that the low-energy behavior of the strength function is well described in the effective three-body “dynamical dineutron model”. The astrophysical rate for the ⁴He+n+n → ⁶He+γ is calculated. Comparison with the previous calculations is performed.