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The generation of angular momentum (intrinsic spin) in fission fragments has recently attracted renewed attention. While several microscopic approaches reproduce the spin distribution qualitatively using projection techniques, the physical…

核理论 · 物理学 2025-12-03 G. Scamps , A. Guilleux , D. Regnier , A. Bernard

Actinide nuclei exhibit mass-asymmetric fission at low energy due to shell structure. The fission-fragment mass distributions produced at high energy tend to have a symmetric shape due to smearing of shell effects. On the other hand, the…

核理论 · 物理学 2025-10-22 S. Takagi , S. Harada , Y. Aritomo , K. Hirose , K. Nishio

Several sources of angular anisotropy for fission fragments and prompt neutrons have been studied in neutron-induced fission reactions. These include kinematic recoils of the target from the incident neutron beam and the fragments from the…

核理论 · 物理学 2020-09-02 A. E. Lovell , P. Talou , I. Stetcu , K. J. Kelly

We present the first fully unrestricted microscopic calculations of the primary fission fragment intrinsic spins and of the fission fragments' relative orbital angular momentum for $^{236}$U$^*$, $^{240}$Pu$^*$, and $^{252}$Cf using the…

核理论 · 物理学 2022-01-14 Aurel Bulgac , Ibrahim Abdurrahman , Kyle Godbey , Ionel Stetcu

We study the spin-down of a neutron star during its early stages due to the neutrino emission. The mechanism we consider is the subsequent collisions of the produced neutrinos with the outer shells of the star. We find that this mechanism…

高能天体物理现象 · 物理学 2014-11-20 Maxim Dvornikov , Claudio O. Dib

We investigate the time evolution of prompt fission $\gamma$ emission due to the presence of ns to ms isomers in the fragments produced in the neutron-induced fission of $^{233,235}$U and in the spontaneous fission of $^{252}$Cf.…

The inclusive energy distributions of fragments (4$\leq$Z$\leq$7) emitted in the reactions $^{16}$O (116 MeV) + $^{27}$Al, $^{28}$Si, $^{20}$Ne (145 MeV) + $^{27}$Al, $^{59}$Co have been measured in the angular range $\theta_{lab} $=…

This paper presents a theoretical description of the spin distributions of fragments from low-energy induced and spontaneous nuclear fission, expressed in an analytical form. The mechanism of pumping high spin values for deformed fission…

A wide variety of emulators have been developed for nuclear physics, particularly for use in quantifying and propagating parametric uncertainties to observables. Most of these methods have been used to emulate structure observables, such as…

核理论 · 物理学 2024-09-26 Karl Daningburg , A. E. Lovell , R. O'Shaughnessy

In quasi-fission, it is unclear what the interaction between the relative orbital angular momentum and the spin of the fragments is from a microscopic perspective. In macroscopic approaches, it is expected that the large value of the…

核理论 · 物理学 2024-11-19 Guillaume Scamps

Fissioning nuclei and fission fragments, nuclear fragments emerging from energetic collisions, or nuclei probed with various external fields can emit one or more pre-equilibrium neutrons, protons, and potentially other heavier nuclear…

核理论 · 物理学 2020-09-23 A. Bulgac

Fireballs of gamma-ray bursts are partially made of free neutrons. Their presence crucially changes the mechanism of the fireball deceleration by an external medium. At late stages of the explosion, neutrons fully decouple from ions and…

天体物理学 · 物理学 2009-11-07 Andrei M. Beloborodov

This study explores the role of nucleon exchange for the generation of the fission fragment angular momenta. For a number of typical fission cases, samples of 10,000 shape evolutions are generated by Langevin simulation and, subsequently,…

核理论 · 物理学 2026-03-31 Jorgen Randrup , Pavel Nadtochy , Christelle Schmitt , Katarzyna Mazurek

This paper presents recent experimental results on the yield of prompt fission $\gamma$ rays from the spontaneous fission of $^{252}$Cf. We use an ionization chamber to tag fission events and measure the masses and kinetic energies of the…

The spin-averaged structure function of the neutron, F_2^n, is extracted from recent deuteron data, taking into account the small but significant corrections due to nuclear effects in the deuteron. At small x, the F_2D/F_2p ratio measured…

核理论 · 物理学 2010-02-17 W. Melnitchouk , A. W. Thomas

The CGMF code implements the Hauser-Feshbach statistical nuclear reaction model to follow the de-excitation of fission fragments by successive emissions of prompt neutrons and $\gamma$ rays. The Monte Carlo technique is used to facilitate…

核理论 · 物理学 2021-08-09 P. Talou , I. Stetcu , P. Jaffke , M. E. Rising , A. E. Lovell , T. Kawano

We propose a novel method to extract the prompt neutron multiplicity distribution, $P(\nu)$, in fission reactions based on correlations between prompt neutrons, $\gamma$ rays, and fragment kinetic energy arising from energy conservation. In…

核理论 · 物理学 2019-11-21 A. E. Lovell , I. Stetcu , P. Talou , G. Rusev , M. Jandel

We report results from an experiment measuring the semi-inclusive reaction $d(e,e'p_s)$ where the proton $p_s$ is moving at a large angle relative to the momentum transfer. If we assume that the proton was a spectator to the reaction taking…

核实验 · 物理学 2019-08-14 A. V. Klimenko , S. E. Kuhn

Three-dimensional hydrodynamical simulations are presented for the direct head-on or off-center collision of two neutron stars, employing a basically Newtonian PPM code but including the emission of gravitational waves and their…

天体物理学 · 物理学 2007-05-23 Maximilian Ruffert , H. -Thomas Janka

Fission fragment angular distributions can provide an important constraint on fission theory, improving predictive fission codes, and are a prerequisite for a precise ratio cross section measurement. Available anisotropy data is sparse,…