Search results for "force"
showing 10 items of 3423 documents
Mirror and triplet displacement energies within nuclear DFT: : numerical stability
2017
Isospin-symmetry-violating class II and III contact terms are introduced into the Skyrme energy density functional to account for charge dependence of the strong nuclear interaction. The two new coupling constants are adjusted to available experimental data on triplet and mirror displacement energies, respectively. We present preliminary results of the fit, focusing on its numerical stability with respect to the basis size.
Neutral-current supernova-neutrino cross sections for 204,206,208Pb calculated by Skyrme quasiparticle random-phase approximation
2019
The present work constitutes a detailed study of neutral-current (NC) supernova-neutrino scattering off the stable even-even lead isotopes 204,206,208Pb. This is a continuation of our previous work [Almosly et al., Phys. Rev. C. 94, 044614 (2016)] where we investigated charged-current processes on the same nuclei. As in the previous work, we have adopted the quasiparticle random-phase approximation (QRPA) as the theory framework and use three different Skyrme interactions to build the involved nuclear wave functions. We test the Skyrme forces by computing the location of the lowest-order isovector spin-multipole giant resonances and comparing with earlier calculations. We have computed the …
Cuckoo's Eggs in Neutron Stars: Can LIGO Hear Chirps from the Dark Sector?
2018
We explore in detail the possibility that gravitational wave signals from binary inspirals are affected by a new force that couples only to dark matter particles. We discuss the impact of both the new force acting between the binary partners as well as radiation of the force carrier. We identify numerous constraints on any such scenario, ultimately concluding that observable effects on the dynamics of binary inspirals due to such a force are not possible if the dark matter is accrued during ordinary stellar evolution. Constraints arise from the requirement that the astronomical body be able to collect and bind at small enough radius an adequate number of dark matter particles, from the requ…
Extreme nuclear magnetic resonance: Zero field, single spins, dark matter….
2019
An unusual regime for liquid-state nuclear magnetic resonance (NMR) where the magnetic field strength is so low that the $J$-coupling (intramolecular spin-spin) interactions dominate the spin Hamiltonian opens a new paradigm with applications in spectroscopy, quantum control, and in fundamental-physics experiments, including searches for well-motivated dark-matter candidates. An interesting possibility is to bring this kind of "extreme NMR" together with another one---single nuclear spin detected with a single-spin quantum sensor. This would enable single-molecule $J$-spectroscopy.
Application of atomic and nuclear techniques to the study of inhomogeneities in electrodeposited α-particle sources
2002
Three α-particle sources made by different methods of electrodeposition were analysed using α-particle spectrometry, Rutherford backscattering (RBS), and atomic force microscopy (AFM) on several surface zones. The thickness and homogeneity of these sources was studied using RBS, and the results were analysed jointly with those obtained with α-particle spectrometry and AFM techniques. The comparison of the electrodeposition methods showed that the most homogeneous electrodeposited zones corresponded to the source made with a stirring cathode.
Nanostructuring and strengthening of LiF crystals by swift heavy ions: AFM, XRD and nanoindentation study
2012
Abstract Modifications of the structure and micromechanical properties of LiF crystals under high-fluence irradiation (10 11 –10 13 ions cm −2 ) with swift C, Ti, Au and U ions of the specific energy of 11.1 MeV/u have been studied. In the case of heavy ions (U, Au), the AFM and SEM results reveal the bulk nanostructure consisting of columnar grains with nano-scale dimensions (50–100 nm). For lighter C ions the structure enriched with prismatic dislocation loops has been observed. High-resolution XRD reciprocal space maps for nano-structured LiF expose a mosaic-type structure with low-angle boundaries between grains.
Skyrme effective pseudopotential up to next-to-next-to leading order
2013
The explicit form of the next-to-next-to-leading order ((NLO)-L-2) of the Skyrme effective pseudopotential compatible with all required symmetries and especially with gauge invariance is presented in a Cartesian basis. It is shown in particular that for such a pseudopotential there is no spin-orbit contribution and that the D-wave term suggested in the original Skyrme formulation does not satisfy the invariance properties. The six new (NLO)-L-2 terms contribute to both the equation of state and the Landau parameters. These contributions to symmetric nuclear matter are given explicitly and discussed.
Systematic T1 improvement for hyperpolarized 129xenon
2015
The spin-lattice relaxation time T1 of hyperpolarized (HP)-(129)Xe was improved at typical storage conditions (i.e. low and homogeneous magnetic fields). Very long wall relaxation times T(1)(wall) of about 18 h were observed in uncoated, spherical GE180 glass cells of ∅=10 cm which were free of rubidium and not permanently sealed but attached to a standard glass stopcock. An "aging" process of the wall relaxation was identified by repeating measurements on the same cell. This effect could be easily removed by repeating the initial cleaning procedure. In this way, a constant wall relaxation was ensured. The Xe nuclear spin-relaxation rate 1/T1(Xe-Xe) due to van der Waals molecules was invest…
MeV–GeV ion induced dislocation loops in LiF crystals
2014
Abstract Formation of prismatic dislocation loops and evolution of dislocation structure in LiF crystals irradiated with swift 238U and 36S ions of specific energy 11 MeV/u at fluences up to 1013 ions cm−2 has been investigated using chemical etching and AFM. It has been shown that prismatic dislocations are formed in the stage of track overlapping above threshold fluences Φ ≈ 109 U cm−2 and Φ ≈ 1010 S cm−2. The diameter of dislocation loops reaches 600–1000 nm for 238U ions and 200 nm for 36S ions. The dislocations created by 238U ions are arranged in rows along the direction of ion beam, whereas 36S ions create freely distributed dislocation loops each of them being oriented along the ion…
Constraining interactions mediated by axion-like particles with ultracold neutrons
2015
We report a new limit on a possible short range spin-dependent interaction from the precise measurement of the ratio of Larmor precession frequencies of stored ultracold neutrons and Hg199 atoms confined in the same volume. The measurement was performed in a ~1μT vertical magnetic holding field with the apparatus searching for a permanent electric dipole moment of the neutron at the Paul Scherrer Institute. A possible coupling between freely precessing polarized neutron spins and unpolarized nucleons of the wall material can be investigated by searching for a tiny change of the precession frequencies of neutron and mercury spins. Such a frequency change can be interpreted as a consequence o…