530 Physik
Refine
Year of publication
- 2017 (6) (remove)
Document Type
- Article (6)
Language
- English (6) (remove)
Has Fulltext
- yes (6)
Is part of the Bibliography
- no (6)
Keywords
- Beam techniques (1)
- Collective flow (1)
- Fission (1)
- General relativity (1)
- General relativity equations & solutions (1)
- Low & intermediate energy heavy-ion reactions (1)
- Magnetohydrodynamics (1)
- Nuclear astrophysics (1)
- Nuclear reactions (1)
- Nucleon induced nuclear reactions (1)
- Nucleosynthesis in explosive environments (1)
- Quark-gluon plasma (1)
- Radiative capture (1)
- Relativistic heavy-ion collisions (1)
- Secondary beams (1)
- Transient & explosive astronomical phenomena (1)
- Unstable nuclei induced nuclear reactions (1)
Institute
- ELEMENTS (6) (remove)
When binary systems of neutron stars merge, a very small fraction of their rest mass is ejected, either dynamically or secularly. This material is neutron-rich and its nucleosynthesis provides the astrophysical site for the production of heavy elements in the Universe, together with a kilonova signal confirming neutron-star mergers as the origin of short gamma-ray bursts. We perform full general-relativistic simulations of binary neutron-star mergers employing three different nuclear-physics equations of state (EOSs), considering both equal- and unequal-mass configurations, and adopting a leakage scheme to account for neutrino radiative losses. Using a combination of techniques, we carry out an extensive and systematic study of the hydrodynamical, thermodynamical, and geometrical properties of the matter ejected dynamically, employing the WinNet nuclear-reaction network to recover the relative abundances of heavy elements produced by each configurations. Among the results obtained, three are particularly important. First, we find that, within the sample considered here, both the properties of the dynamical ejecta and the nucleosynthesis yields are robust against variations of the EOS and masses. Second, using a conservative but robust criterion for unbound matter, we find that the amount of ejected mass is ≲10−3 M⊙, hence at least one order of magnitude smaller than what normally assumed in modelling kilonova signals. Finally, using a simplified and gray-opacity model we assess the observability of the infrared kilonova emission finding, that for all binaries the luminosity peaks around ∼1=2 day in the H-band, reaching a maximum magnitude of −13, and decreasing rapidly after one day.
We investigate the effect of large magnetic fields on the (2 + 1)-dimensional reduced-magnetohydrodynamical expansion of hot and dense nuclear matter produced in √sNN = 200 GeV Au+Au collisions. For the sake of simplicity,we consider the casewhere themagnetic field points in the direction perpendicular to the reaction plane. We also consider this field to be external, with energy density parametrized as a two-dimensional Gaussian. The width of the Gaussian along the directions orthogonal to the beam axis varies with the centrality of the collision. The dependence of the magnetic field on proper time (τ ) for the case of zero electrical conductivity of the QGP is parametrized following Deng et al. [Phys. Rev. C 85, 044907 (2012)], and for finite electrical conductivity following Tuchin [Phys. Rev. C 88, 024911 (2013)].We solve the equations of motion of ideal hydrodynamics for such an external magnetic field. For collisions with nonzero impact parameter we observe considerable changes in the evolution of the momentum eccentricities of the fireball when comparing the case when the magnetic field decays in a conducting QGP medium and when no magnetic field is present. The elliptic-flow coefficient v2 of π− is shown to increase in the presence of an external magnetic field and the increment in v2 is found to depend on the evolution and the initial magnitude of the magnetic field.
Ion optical calculations for a storage ring at the present GSI facility for direct proton-induced reactions relevant for different astrophysical processes are presented. As an example case, the 59Cu(p,γ) and 59Cu(p,α) reactions are shown. The branching of these two reactions is important in X-ray burst scenarios, since it determines the breakout out of the major 56Ni waiting point.
One of the aims of the SPARC collaboration [1] at FAIR is to perform precision atomic physics expe- riments with highly charged heavy ions at the High Energy Storage Ring (HESR). An internal target is indis- pensably an integral part for many such experiments. Ions with different charge states, which are obtained as a result of interaction of an ion beam with the target, need to be effectively separated and detected. In this work we present ion optical studies unambiguously showing the feasibility of SPARC experiments at the HESR.
The 124Xe(p,γ) reaction has been measured for the first time at energies around the Gamow window by using stored ions at the ESR facility. The desired beam energies below 10 MeV/u introduce new experimental challenges like windowless ions detection under UHV conditions, extremely short beam lifetimes and efficient beam deceleration and cooling, all of which have been successfully met.
We discuss the possibility to build a neutron target for nuclear reaction studies in inverse kinematics utilizing a storage ring and radioactive ion beams. The proposed neutron target is a specially designed spallation target surrounded by a large moderator of heavy water (D2O). We present the resulting neutron spectra and their properties as a target. We discuss possible realizations at different experimental facilities.