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In this contribution, current status and future prospects of our ongoing project is summarized. In the inner crust of neutron stars, a variety of crystalline structures may emerge, as a result of competition of Coulomb and nuclear interactions, which are immersed in a sea of superfluid neutrons. The best quantum mechanical approach to study properties of dripped neutrons under a periodic potential is the band theory of solids. Concerning the band structure effects on transport properties of neutrons, however, situation is complicated and there has not been established a clear consensus yet. To provide a robust conclusion on the band structure effects, we have developed a fully-microscopic time-dependent band theory based on time-dependent density functional theory (TDDFT), taking full account of Fermionic superfluditiy. We have successfully developed a parallel computational code and applied it to the slab phase of nuclear matter. We introduce ongoing works and discuss possible future directions., Comment: 10 pages, 1 figure, 1 table, Proceedings of the 34th IUPAP Conference on Computational Physics (CCP2023), Kobe, Japan, Aug. 4-8, 2023

Background: The inner crust of neutron stars consists of a Coulomb lattice of neutron-rich nuclei, immersed in a sea of superfluid neutrons with background relativistic electron gas. A proper quantum mechanical treatment for such a system under a periodic potential is the band theory of solids. The effect of band structure on the effective mass of dripped neutrons, the so-called \textit{entrainment effect}, is currently in a debatable situation, and it has been highly desired to develop a nuclear band theory taking into account neutron superfluidity in a fully self-consistent manner. Purpose: The main purpose of the present work is twofold: 1) to develop a formalism of the time-dependent self-consistent band theory, taking full account of nuclear superfluidity, based on time-dependent density functional theory (TDDFT) extended for superfluid systems, and 2) to quantify the effects of band structure and superfluidity on crustal properties, applying the formalism to the slab phase of nuclear matter in the $\beta$ equilibrium. Results: Static calculations have been performed for a range of baryon (nucleon) number density ($n_b=0.04-0.07$ fm$^{-3}$) under the $\beta$-equilibrium condition with and without superfluidity, for various inter-slab spacings. From a dynamic response to an external potential, we extract the collective mass of a slab and that of protons immersed in neutron superfluid. From the results, we find that the collective mass of a slab is substantially reduced by 57.5--82.5\% for $n_b=0.04-0.07$ fm$^{-3}$, which corresponds to an enhancement of conduction neutron number density and, thus, to a reduction of the neutron effective mass, which we call the anti-entrainment effect. We discuss novel phenomena associated with superfluidity, quasiparticle resonances in the inner crust, which are absent in normal systems. *shortened due to the arXiv word limit., Comment: 21 pages, 11 figures, 4 tables. v4 - Version accepted for publication in Physical Review C, selected as an Editors' Suggestion

We investigate outer crust compositions for a wide range of magnetic field strengths, up to $B\simeq 4\times10^{18}$ G, employing the latest experimental nuclear masses supplemented with various mass models. The essential effects of the magnetic field are twoholds: 1) Enhancement of electron fraction, which is connected to that of protons via the charge neutrality condition, due to the Landau-Rabi quantization of electron motion perpendicular to the field, namely, neutron-richness is suppressed for a given pressure. As a result, 2) nuclei can exist at higher pressures without dripping out neutrons. By exploring optimal outer-crust compositions from all possible nuclei predicted by theoretical models, we find that neutron-rich heavy nuclei with neutron magic numbers 50, 82, 126, as well as 184, with various proton numbers emerge for $B\gtrsim 10^{17}$ G. Moreover, we show that superheavy nuclei with proton numbers $Z\ge104$, including unknown elements such as $Z=119, 120, 122$, and/or $124$, depending on mass models, may emerge as an equilibrium composition at bottom layers of the outer crust for $B\gtrsim 10^{18}$ G, which are extremely neutron-rich ($N\approx 260$-$287$, i.e., $N/Z\approx 2.2$-$2.4$). We point out that those extremely neutron-rich superheavy nuclei locate around the next neutron magic number $N=258$ after $N=184$, underlining importance of nuclear structure calculations under such really exotic, extreme conditions. We demonstrate how the superstrong magnetic field substantially alters crustal properties of neutron stars, which may have detectable consequences., Comment: 7 pages, 4 figures (main texts) + 15 pages, 3 figures, 21 tables (supplement) - Submitted to Physical Review Letters

The International Linear Collider (ILC) is on the table now as a new global energy-frontier accelerator laboratory taking data in the 2030s. The ILC addresses key questions for our current understanding of particle physics. It is based on a proven accelerator technology. Its experiments will challenge the Standard Model of particle physics and will provide a new window to look beyond it. This document brings the story of the ILC up to date, emphasizing its strong physics motivation, its readiness for construction, and the opportunity it presents to the US and the global particle physics community., Comment: 356 pages, Large pdf file (40 MB) submitted to Snowmass 2021; v2 references to Snowmass contributions added, additional authors; v3 references added, some updates, additional authors

Background: In the solid crust of neutron stars, a variety of crystalline structure may exist. Recently the band theory of solids has been applied to the inner crust of neutron stars and significance of the entrainment between dripped neutrons and the solid crust was advocated. Since it influences interpretations of various phenomena of neutron stars, it has been desired to develop deeper understanding of the microphysics behind. Purpose: The purpose of the present article is to propose a fully self-consistent microscopic framework for describing time-dependent dynamics of neutron star matter, which allows us to explore diverse properties of nuclear matter, including the entrainment effect. Results: As the first application of the time-dependent self-consistent band theory for nuclear systems, we investigate the slab phase of nuclear matter with various proton fractions. From a dynamic response of the system to an external force, we extract the collective mass of a slab, associated with entrained neutrons as well as bound nucleons. We find that the extracted collective mass is smaller than a naive estimation based on a potential profile and single-particle energies. We show that the reduction is mainly caused by "counterflow" of dripped neutrons towards the direction opposite to the motion of the slabs. We interpret it as an "anti-entrainment" effect. As a result, the number of effectively bound neutrons is reduced, indicating an enhancement of the number density of conduction neutrons. We demonstrate that those findings are consistent with a static treatment in the band theory of solids. *shortened due to the arXiv's word limit., Comment: 19 pages, 10 figures, 3 tables; v2 - A figure (Fig. 10) has been added. Version accepted for publication in Physical Review C

We present results of collisions of $^{90}$Zr+$^{90}$Zr and $^{96}$Zr+$^{96}$Zr obtained within time-dependent density functional theory (TDDFT) extended to superfluid systems, known as time-dependent superfluid local density approximation (TDSLDA). We discuss qualitatively new features occurring in collisions of two superfluid nuclei at energies in the vicinity of the Coulomb barrier. We show that a \textit{solitonic excitation} -- an abrupt pairing phase distortion -- reported previously [P.~Magierski et al., Phys. Rev. Lett. \textbf{119}, 042501 (2017)], increases the barrier for capture generating effective repulsion between colliding nuclei. Moreover we demonstrate that pairing field leads to qualitatively different dynamics at the Coulomb barrier which manifests itself in a slower evolution of deformation towards a compact shape. Last but not least, we show that magnitude of pairing correlations can be dynamically enhanced after collision. We interpret it as a dynamically induced $U(1)$ symmetry breaking, which leads to large-amplitude oscillations of pairing field and bear similarity to the pairing Higgs mechanism., Comment: 13 pages (including supplemental material), 6 figures

We report the first direct measurement of differential transfer cross sections using a Recoil Mass Spectrometer. Absolute differential $1p$ and $2p$-stripping cross sections at $\theta_\mathrm{c.m.}=180^\circ$ have been determined for the system $^{16}$O+$^{142}$Ce by detecting the heavier target-like ions at the focal plane of the Heavy Ion Reaction Analyzer. Focal plane spectra have been compared with the results of a semi-microscopic Monte-Carlo simulation to unambiguously identify the transfer channels. Transmission efficiency of the target-like ions through the spectrometer has also been estimated using the simulation. The methodology adopted in this work can be applied to other recoil separators. The measured excitation functions for the reactions $^{142}\mathrm{Ce(}^{16}\mathrm{O,}^{15}\mathrm{N)}^{143}\mathrm{Pr}$ and $^{142}\mathrm{Ce(}^{16}\mathrm{O,}^{14}\mathrm{C)}^{144}\mathrm{Nd}$ have been compared with coupled reaction channel calculations. An excellent matching between measurement and theory has been obtained. For $1p$-stripping, major contribution to the cross section has been found to be the transfer of a proton from $^{16}\mathrm{O}$ to the $2d_{\frac{5}{2}}$ excited state of $^{143}\mathrm{Pr}$, leaving behind $^{15}\mathrm{N}$ in the $1p_{\frac{1}{2}}$ ground state. Transfer of a cluster of two protons from $^{16}\mathrm{O}$ to the $2^{+}$ excited state of $^{144}\mathrm{Nd}$, resulting in $^{14}\mathrm{C}$ in the $0^{+}$ ground state, appears to be the most probable cause for $2p$-stripping. Measured transfer probabilities for $1p$ and $2p$ channels have been compared with Time-Dependent Hartree-Fock calculations. Proton stripping channels are found to be more favourable compared to neutron pick-up channels. However, the theory overpredicts measurement hinting at the need for extended approaches with explicit treatment of pairing correlations in the calculations.

Quantized vortices carry the angular momentum in rotating superfluids, and are key to the phenomenon of quantum turbulence. Advances in ultra-cold atom technology enable quantum turbulence to be studied in regimes with both experimental and theoretical control, unlike the original contexts of superfluid helium experiments. While much work has been performed with bosonic systems, detailed studies of fermionic quantum turbulence are nascent, despite wide applicability to other contexts such as rotating neutron stars. In this paper, we present the first large-scale study of quantum turbulence in rotating fermionic superfluids using an accurate orbital based time-dependent density functional theory (DFT) called the superfluid local density approximation (SLDA). We identify two different modes of turbulent decay in the dynamical equilibration of a rotating fermionic superfluid, and contrast these results with a computationally simpler orbital-free DFT, which we find can qualitatively reproduce these decay mechanisms if dissipation is explicitly included. These results demonstrate that one-body dissipation mechanisms intrinsic to fermionic superfluids play a key role differentiating fermionic from bosonic turbulence, but also suggest that simpler orbital-free theories may be corrected so that these more efficient techniques can be used to model extended physical systems such as neutron superfluids in neutron stars., Comment: 13 pages, 8 figures. Accompanying movies can be found at http://wlazlowski.fizyka.pw.edu.pl/supplement/sm-rotating-turbulence/

Background: Microscopic mean-field approaches have been successful in describing the most probable reaction outcomes in low-energy heavy-ion reactions. However, those approaches are known to severely underestimate dispersions of observables around the average values that has limited their applicability. Recently it has been shown that a quantal transport approach based on the stochastic mean-field (SMF) theory significantly improves the description, while its application has been limited so far to fragment mass and charge dispersions. Purpose: In this work, we extend the quantal transport approach based on the SMF theory for relative kinetic energy dissipation and angular momentum transfer in low-energy heavy-ion reactions. Results: As the first application of the proposed formalism, we consider the radial linear momentum dispersion, neglecting the coupling between radial and angular momenta. We analyze the total kinetic energy (TKE) distribution of binary reaction products in the $^{136}$Xe+$^{208}$Pb reaction at $E_\mathrm{c.m.}=526$ MeV and compare with experimental data. From time evolution of single-particle orbitals in TDHF, the radial diffusion coefficient is computed on a microscopic basis, while a phenomenological treatment is introduced for the radial friction coefficient. By solving the quantal diffusion equation for the radial linear momentum, the dispersion of the radial linear momentum is obtained, from which one can construct the TKE distribution. We find that the calculations provide a good description of the TKE distribution for large values of energy losses, TKEL $\gtrsim$ 150 MeV. However, the calculations underestimate the TKE distribution for smaller energy losses. Further studies are needed to improve the technical details of calculations. (Shortened due to the word limit), Comment: 17 pages, 6 figures, 2 tables (plus 5 figures in Appendix); v2 - Version accepted for publication in Physical Review C, with additional analysis on DD-TDHF in Appendix C

Background: In recent years, substantial efforts have been made for the study of multinucleon transfer reactions at energies around the Coulomb barrier both experimentally and theoretically, aiming at the production of unknown neutron-rich heavy nuclei. It is crucial to provide reliable theoretical predictions based on microscopic theories with sufficient predictive power. Purpose: This paper aims to clarify the applicability of the quantal diffusion approach based on the stochastic mean-field (SMF) theory for multinucleon transfer processes. Isotope production cross sections are evaluated for the reactions of $^{64}$Ni+$^{208}$Pb at $E_{c.m.}$=268 MeV and $^{58}$Ni+$^{208}$Pb at $E_{c.m.}$=270 MeV and are compared with available experimental data. Methods: Three-dimensional time-dependent Hartree-Fock (TDHF) calculations are carried out for a range of initial orbital angular momenta with Skyrme SLy4d functional. Quantal diffusion equations, derived based on the SMF theory, for variances and covariance of neutron and proton numbers of reaction products are solved, with microscopic drift and diffusion coefficients obtained from the time evolution of occupied single-particle orbitals in TDHF. Secondary deexcitation processes, both particle evaporation and fission, are simulated by a statistical model, GEMINI++. Results: We find that the quantal diffusion approach reproduces the measured cross sections for abundant reaction products, including both projectile-like and target-like fragments, as well as fragments of transfer-induced fission. The results underline the importance of beyond mean-field effects in describing multinucleon transfer processes. We emphasize that the quantal diffusion description does not involve any adjustable parameters, once an energy density functional is given. Possible future directions are discussed. (Shortened due to the word limit), Comment: 26 pages, 12 figures (plus 4 figures, 2 tables in Appendix); v2 - Version accepted for publication in Physical Review C; Supplemental movies can be found at https://www.youtube.com/playlist?list=PLKTmRVRArzsQUKpMiOXAzliVSgzjD0ZG2

Time-dependent Hartree--Fock (TDHF) method has been applied to various low-energy nuclear reactions, such as fusion, fission, and multinucleon transfer reactions. In this Mini Review, we summarize recent attempts to bridge a microscopic nuclear reaction theory, TDHF, and a macroscopic aspect of nuclear reactions through nucleus--nucleus potentials and energy dissipation from macroscopic degrees of freedom to microscopic ones obtained from TDHF in various colliding systems from light to heavy mass regions., Comment: 11 pages, 2 figures; accepted for publication in Research Topic "Advances in Time-Dependent Methods for Nuclear Structure and Dynamics" in Frontiers in Physics

Time-dependent Hartree-Fock (TDHF) theory has been a powerful tool in describing a variety of complex nuclear dynamics microscopically without empirical parameters. In this contribution, recent advances in nuclear dynamics studies with TDHF and its extensions are briefly reviewed, along the line with the study of multinucleon transfer (MNT) reactions. The latter lies at the core of this Research Topic, whose application for production of extremely neutron-rich nuclei has been extensively discussed in recent years. Having in mind the ongoing theoretical developments, it is envisaged how microscopic theories may contribute to the future MNT study., Comment: 13 pages, 1 figure; An invited mini review to be published in: Research Topic "Structure, Reaction and Production Mechanism of Extremely Neutron-Rich Nuclei" (ed.) N. Wang, A. Bonaccorso, and S.-G. Zhou, in Frontiers in Physics, section Nuclear Physics

Cold atoms experiments offer invaluable information on superfluid dynamics, including decay cascades of topological defects. While the cascade properties are well established for Bose systems, our understanding of their behavior in Fermi counterparts is very limited, in particular in spin-imbalanced systems, where superfluid (paired) and normal (unpaired) particles naturally coexist giving rise to complex spatial structure of the atomic cloud. Here we show, based on a newly developed microscopic approach, that the decay cascades of topological defects are dramatically modified by the spin-polarization. We demonstrate that decay cascades end up at different stages: "dark soliton", "vortex ring" or "vortex line", depending on the polarization. We reveal that it is caused by sucking of unpaired particles into the soliton's internal structure. As a consequence vortex reconnections are hindered and we anticipate that quantum turbulence phenomenon can be significantly affected, indicating new physics induced by polarization effects., Comment: Published version. Manuscript with included Supplementary Material. Movies available at http://www.if.pw.edu.pl/~gabrielw/supplement/1/supplement.html

Multinucleon transfer processes in low-energy heavy ion reactions have attracted increasing interest in recent years aiming at production of new neutron-rich isotopes. Clearly, it is an imperative task to further develop understanding of underlying reaction mechanisms to lead experiments to success. In this paper, from systematic time-dependent Hartree-Fock calculations for the $^{238}$U+$^{124}$Sn reaction, it is demonstrated that transfer dynamics depend strongly on the orientations of $^{238}$U, quantum shells, and collision energies. Two important conclusions are obtained: (i) Experimentally observed many-proton transfer from $^{238}$U to $^{124}$Sn can be explained by a multinucleon transfer mechanism governed by enhanced neck evolution in tip collisions; (ii) Novel reaction dynamics are observed in tip collisions at energies substantially above the Coulomb barrier, where a number of nucleons are transferred from $^{124}$Sn to $^{238}$U, producing transuranium nuclei as primary reaction products, that could be a means to synthesize superheavy nuclei. Both results indicate the importance of the neck (shape) evolution dynamics, which are sensitive to the orientations, shell effects and collision energies, for exploring possible pathways to produce new unstable nuclei., Comment: 10 pages, 3 figures; v2 - Version accepted for publication in PRC as a Rapid Communication

Recently, we have reported a novel role of pairing in low-energy heavy ion reactions at energies above the Coulomb barrier, which may have a detectable impact on reaction outcomes, such as the kinetic energy of fragments and the fusion cross section [arXiv:1611.10261, arXiv:1702.00069]. The phenomenon mimics the one studied experimentally with ultracold atomic gases, where two clouds of fermionic superfluids with different phases of the pairing fields are forced to merge, inducing various excitation modes of the pairing field. Although it originates from the phase difference of the pairing fields, the physics behind it is markedly different from the so-called Josephson effect. In this short contribution, we will briefly outline the results discussed in our recent papers and explain relations with the field of ultracold atomic gases., Comment: 5 pages, 3 figures, Account of an invited talk given at the International Conference on heavy-ion collisions at near-barrier energies (FUSION17), Hobart, Tasmania, Australia, Feb. 20-24, 2017

Background: At the forefront of the nuclear science, production of new neutron-rich isotopes is continuously pursued at accelerator laboratories all over the world. To explore the currently-unknown territories in the nuclear chart far away from the stability, reliable theoretical predictions are inevitable. Purpose: To provide a reliable prediction of production cross sections taking into account secondary deexcitation processes, both particle evaporation and fission, a new method called TDHF+GEMINI is proposed, which combines the microscopic time-dependent Hartree-Fock (TDHF) theory with a sophisticated statistical compound-nucleus deexcitation model, GEMINI++. Results: The method is applied for multinucleon transfer processes in low-energy heavy ion reactions. It is shown that the inclusion of secondary deexcitation processes, which are dominated by neutron evaporation in the present systems, substantially improves agreement with the experimental data. The magnitude of the evaporation effects is very similar to the one observed in GRAZING calculations. TDHF+GEMINI provides better description of the absolute value of the cross sections for channels involving transfer of more than one protons, compared with the GRAZING results. However, there remain discrepancies between the measurements and the calculated cross sections, indicating a limit of the theoretical framework that works with a single mean-field potential. Possible causes of the discrepancies are discussed. Conclusions: In order to perfectly reproduce experimental cross sections for multinucleon transfer processes, one should go beyond the standard self-consistent mean-field description. Nevertheless, the proposed method will provide valuable information to optimize production mechanisms of new neutron-rich nuclei through its microscopic, non-empirical predictions. (Shortened due to the word limit), Comment: 13 pages, 10 figures, 1 table, v3 - Version accepted for publication in PRC

We investigate the role of the pairing field dynamics in low-energy heavy ion reactions within the nuclear time-dependent density functional theory extended to superfluid systems. Recently, we have reported on unexpectedly large effects associated with the relative phase of the pairing field of colliding nuclei on the reaction outcomes, such as the total kinetic energy and the fusion cross section [P. Magierski, K. Sekizawa, and G. Wlaz{\l}owski, arXiv:1611.10261 [nucl-th]]. We have elucidated that the effects are due to creation of a "domain wall" or a "solitonic structure" of the pairing field in the neck region, which hinders energy dissipation as well as the neck formation, leading to significant changes of the reaction dynamics. The situation nicely mimics the one extensively studied experimentally with ultracold atomic gases, where two clouds of superfluid atoms possessing different phases of the pairing field are forced to merge, creating various topological excitations, quantum vortices and solitons, as well as Josephson currents. In this paper, we present unpublished results for a lighter system, namely, $^{44}$Ca+$^{44}$Ca. It is shown that the pairing effects on the fusion hindrance are rather small in lighter systems, due to a strong tendency towards fusion, which is consistent with an earlier study., Comment: 8 pages, 2 figures, Proceedings of the 26th International Nuclear Physics Conference (INPC2016), Adelaide, Australia, Sep. 11-16, 2016

Recent experiments revealed intriguing similarities in the $^{64}$Ni+$^{207}$Pb, $^{132}$Xe+$^{208}$Pb, and $^{238}$U+$^{238}$U reactions at energies around the Coulomb barrier. The experimental data indicate that for all systems substantial energy dissipation takes place, in the first stage of the reaction, although the number of transferred nucleons is small. On the other hand, in the second stage, a large number of nucleons are transferred with small friction and small consumption of time. To understand the observed behavior, various reactions were analyzed based on the microscopic time-dependent Hartree-Fock (TDHF) theory. From a systematic analysis for $^{40,48}$Ca+$^{124}$Sn, $^{40}$Ca+$^{208}$Pb, $^{40}$Ar+$^{208}$Pb, $^{58}$Ni+$^{208}$Pb, $^{64}$Ni+$^{238}$U, $^{136}$Xe+ $^{198}$Pt, and $^{238}$U+$^{238}$U reactions, we find that TDHF reproduces well the measured trends. In addition, the Balian-V\'en\'eroni variational principle is applied to head-on collisions of $^{238}$U+$^{238}$U, and the variance of the fragment masses is compared with the experimental data, showing significant improvement. The underlying reaction mechanisms and possible future studies are discussed., Comment: 16 pages, 2 figures, Proceedings of the XXIII Nuclear Physics Workshop ,,Marie & Pierre Curie", Kazimierz Dolny, Poland, Sep. 27 - Oct. 2, 2016; v3 - Version accepted for publication in Acta Physica Polonica B

We demonstrate, within symmetry unrestricted time-dependent density functional theory, the existence of new effects in low-energy nuclear reactions which originate from superfluidity. The dynamics of the pairing field induces solitonic excitations in the colliding nuclear systems, leading to qualitative changes in the reaction dynamics. The solitonic excitation prevents collective energy dissipation and effectively suppresses fusion cross section. We demonstrate how the variations of the total kinetic energy of the fragments can be traced back to the energy stored in the superfluid junction of colliding nuclei. Both contact time and scattering angle in non-central collisions are significantly affected. The modification of the fusion cross section and possibilities for its experimental detection are discussed., Comment: Manuscript with included Supplemental online material, published version

We investigate the dynamics of a quantized vortex and a nuclear impurity immersed in a neutron superfluid within a fully microscopic time-dependent three-dimensional approach. The magnitude and even the sign of the force between the quantized vortex and the nuclear impurity have been a matter of debate for over four decades. We determine that the vortex and the impurity repel at neutron densities, 0.014 fm$^{-3}$ and 0.031 fm$^{-3}$, which are relevant to the neutron star crust and the origin of glitches, while previous calculations have concluded that the force changes its sign between these two densities and predicted contradictory signs. The magnitude of the force increases with the density of neutron superfluid, while the magnitude of the pairing gap decreases in this density range., Comment: 4 pages, 2 figures, Talk given at the 14th International Symposium on "Nuclei in the Cosmos" (NIC-XIV), June 19-24, 2016, Toki Messe, Niigata, Japan

The nature of the interaction between superfluid vortices and the neutron star crust, conjectured by Anderson and Itoh in 1975 to be at the heart vortex creep and the cause of glitches, has been a long-standing question in astrophysics. Using a qualitatively new approach, we follow the dynamics as superfluid vortices move in response to the presence of "nuclei" (nuclear defects in the crust). The resulting motion is perpendicular to the force, similar to the motion of a spinning top when pushed. We show that nuclei repel vortices in the neutron star crust, and characterize the force as a function of the vortex-nucleus separation., Comment: supplemental materials included

Background: Multinucleon transfer (MNT) and quasifission (QF) processes are dominant processes in low-energy collisions of two heavy nuclei. They are expected to be useful to produce neutron-rich unstable nuclei. Nuclear dynamics leading to these processes depends sensitively on nuclear properties such as deformation and shell structure. Purpose: We elucidate reaction mechanisms of MNT and QF processes involving heavy deformed nuclei, making detailed comparisons between microscopic time-dependent Hartree-Fock (TDHF) calculations and measurements for the $^{64}$Ni+$^{238}$U reaction. Methods: Three-dimensional Skyrme-TDHF calculations are performed. Particle-number projection method is used to evaluate MNT cross sections from the TDHF wave function after collision. Results: Fragment masses, total kinetic energy (TKE), scattering angle, contact time, and MNT cross sections are investigated for the $^{64}$Ni+$^{238}$U reaction. They show reasonable agreements with measurements. At small impact parameters, collision dynamics depends sensitively on the orientation of deformed $^{238}$U. In tip (side) collisions, we find a larger (smaller) TKE and a shorter (longer) contact time. In tip collisions, we find a strong influence of quantum shells around $^{208}$Pb. Conclusions: It is confirmed that the TDHF calculations reasonably describe both MNT and QF processes in the $^{64}$Ni+$^{238}$U reaction. Analyses of this system indicates the significance of the nuclear structure effects such as deformation and quantum shells in nuclear reaction dynamics at low energies., Comment: 14 pages, 10 figures; v2 - Additional calculations were performed and results shown in Sec.III B have been revised. Version accepted for publication in PRC, selected as Editors' Suggestion. See also Supplemental Material at http://link.aps.org/supplemental/10.1103/PhysRevC.93.054616 for movies of the reactions

Time-dependent Hartree-Fock (TDHF) theory has achieved a remarkable success in describing and understanding nuclear many-body dynamics from nucleons' degrees of freedom. We here report our investigation of multinucleon transfer (MNT) processes employing the TDHF theory. To calculate transfer probabilities for channels specified by the number of protons and neutrons included in reaction products, a particle-number projection (PNP) method has been developed. The PNP method is also used to calculate excitation energies of reaction products. Combined use of the PNP method with a statistical model, we can evaluate MNT cross sections taking account of effects of particle evaporation. Using these methods, we evaluate MNT cross sections for $^{40,48}$Ca+$^{124}$Sn, $^{40}$Ca+$^{208}$Pb, and $^{58}$Ni+$^{208}$Pb reactions. From systematic analyses, we find that cross sections for channels with a large reaction probability are in good agreement with experimental data. However, the agreement becomes less accurate as the number of transferred nucleons increases. Possible directions to improve the description are discussed., Comment: To be published in the ebook "Progress of time-dependent nuclear reaction theory" honoring Prof. Joachim Maruhn's retirement

We theoretically investigate multinucleon transfer (MNT) processes in $^{238}$U+$^{124}$Sn reaction at $E_\mathrm{lab}=5.7$ MeV/$A$ using the time-dependent Hartree-Fock (TDHF) theory. For this reaction, measurements of MNT processes have been reported, showing substantial MNT cross sections accompanying more than ten protons. From the calculation, we find that the amount of transferred nucleons depends much on the relative orientation between the deformation axis of $^{238}$U and the relative vector connecting centers of $^{238}$U and $^{124}$Sn nuclei. We find a formation of thick neck when the $^{238}$U collides from its tip with $^{124}$Sn. However, the neck formation is substantially suppressed when $^{238}$U collides from its side. We have found that a large number of protons are transferred in the tip collision. This is caused by the breaking of the neck and subsequent absorption of nucleons in the neck region. We thus conclude that the measured MNT processes involving about ten protons originate from the neck breaking dynamics in the tip collisions of a deformed $^{238}$U nucleus., Comment: 4 pages, 2 figures, Poster given at 2nd Conference of Advances in Radioactive Isotope Science (ARIS2014), June 1-6, 2014, Tokyo, Japan

Background: The time-dependent Hartree-Fock (TDHF) theory has been successful in describing low-energy heavy ion collisions. Recently, we have shown that multinucleon transfer processes can be reasonably described in the TDHF theory combined with the particle-number projection technique. Purpose: In this work, we propose a theoretical framework to analyze properties of reaction products in TDHF calculations. Methods: TDHF calculation in three-dimensional Cartesian grid representation combined with particle number projection method. Results: We develop a theoretical framework to calculate expectation values of operators in the TDHF wave function after collision with the particle-number projection. To show how our method works in practice, the method is applied to $^{24}$O+$^{16}$O collisions for two quantities, angular momentum and excitation energy. The analyses revealed following features of the reaction: The nucleon removal proceeds gently, leaving small values of angular momentum and excitation energy in nucleon removed nuclei. Contrarily, nuclei receiving nucleons show expectation values of angular momentum and excitation energy which increase as the incident energy increases. Conclusions: We have developed a formalism to analyze properties of fragment nuclei in the TDHF theory combined with the particle-number projection technique. The method will be useful for microscopic investigations of reaction mechanisms in low-energy heavy ion collisions as well as for evaluating effects of particle evaporation on multinucleon transfer cross sections., Comment: 10 pages, 6 figures; v2 - Version accepted for publication in PRC

We present a microscopic calculation of multi-nucleon transfer reactions employing the time-dependent Hartree-Fock (TDHF) theory. In our previous publication [Phys. Rev. C 88, 014614 (2013)], we reported our analysis for the multi-nucleon transfer processes for several systems. Here we discuss effects of particle evaporation processes on the production cross sections. Since particle evaporation processes may not be described adequately by the TDHF calculations, we evaluate them using a statistical model. As an input of the statistical model, excitation energies of the final fragments are necessary. We evaluate them from the TDHF wave function after collisions, extending the particle number projection technique. From the calculation, the particle evaporation effects are found to improve descriptions of the production cross sections. However, the production cross sections are still underestimated for processes where a number of protons are transferred. Possible origins of the discrepancy are discussed., Comment: 4 pages, 1 figure, Talk given at VI International Conference FUSION14, Feb. 24-28, 2014, New Delhi, India

Multinucleon transfer processes in heavy-ion reactions at energies slightly above the Coulomb barrier are investigated in a fully microscopic framework of the time-dependent Hartree-Fock (TDHF) theory. Transfer probabilities are calculated from the TDHF wave function after collision using the projection operator method which has recently been proposed by Simenel (C. Simenel, Phys. Rev. Lett. 105, 192701 (2010)). We show results of the TDHF calculations for transfer cross sections of the reactions of $^{40,48}$Ca+$^{124}$Sn at $E_{lab}=$ 170, 174 MeV, $^{40}$Ca+$^{208}$Pb at $E_{lab}=$ 235, 249 MeV, and $^{58}$Ni+$^{208}$Pb at $E_{lab}=$ 328.4 MeV, for which measurements are available. We find the transfer processes show different behaviors depending on the $N/Z$ ratios of the projectile and the target, and the product of the charge numbers, $Z_P Z_T$. When the projectile and the target have different $N/Z$ ratios, fast transfer processes of a few nucleons towards the charge equilibrium of the initial system occur in reactions at large impact parameters. As the impact parameter decreases, a neck formation is responsible for the transfer. A number of nucleons are transferred by the neck breaking when two nuclei dissociate, leading to transfers of protons and neutrons in the same direction. Comparing cross sections by theory and measurements, we find the TDHF theory describes the transfer cross sections of a few nucleons reasonably. As the number of transferred nucleons increases, the agreement becomes less accurate. The TDHF calculation overestimates transfer cross sections accompanying a large number of neutrons when more than one proton are transferred. Comparing our results with those by other theories, we find the TDHF calculations give qualitatively similar results to those of direct reaction models such as GRAZING and Complex WKB., Comment: 24 pages, 27 figures; v2 - a figure and a reference added, some figures are revised. Version accepted for publication in PRC