43842936
Study of the Energy Modulated Electron Cyclotron Resonance Ion Source for the Coupled RFQ-SFRFQ Cavity
The coupled RFQ and SFRFQ cavity has been manufactured and tested recently. According to the beam dynamic design, the input He beam within 120° phase width is designed for the cavity to achieve over 98% transmission efficiency. An energy modulated electron cyclotron resonance (ECR) ion source was proposed and simulated. To achieve the 1% energy modulation on the 30keV direct current (DC) beam, two simplified RF power feeding structures for beam bunching were studied. The simulations show positive results as well as the bunched beam is achieved by the energy modulated ECR ion source.
53520183
Multidimensionally constrained relativistic mean-field study of triple-humped barriers in actinides
Background: Potential energy surfaces (PES's) of actinide nuclei are characterized by a two-humped barrier structure. At large deformations beyond the
119112485
Multidimensionally constrained relativistic mean field model and applications in actinide and transfermium nuclei
We present some results of potential energy surfaces of actinide and transfermium nuclei from multidimensionally constrained relativistic mean field (MDC-RMF) models. Recently we developed multidimensionally constrained covariant density functional theories (MDC-CDFT), in which all shape degrees of freedom beta with even mu are allowed, and the functional can be one of the following four forms: the meson exchange or point-coupling nucleon interactions combined with the nonlinear or density-dependent couplings. In MDC-RMF models, the pairing correlations are treated with the BCS method. With MDC-RMF models, the potential energy surfaces of even-even actinide nuclei were investigated and the effect of triaxiality on the fission barriers in these nuclei was discussed. The nonaxial reflection-asymmetric beta(32) shape in some transfermium nuclei with N = 150, namely Cm-246, Cf-248, Fm-250 and No-252, were also studied.
6082134
Description and comparison of algorithms for correcting anisotropic magnification in cryo-EM images.
Single particle electron cryomicroscopy (cryo-EM) allows for structures of proteins and protein complexes to be determined from images of non-crystalline specimens. Cryo-EM data analysis requires electron microscope images of randomly oriented ice-embedded protein particles to be rotated and translated to allow for coherent averaging when calculating three-dimensional (3D) structures. Rotation of 2D images is usually done with the assumption that the magnification of the electron microscope is the same in all directions. However, due to electron optical aberrations, this condition is not met with some electron microscopes when used with the settings necessary for cryo-EM with a direct detector device (DDD) camera. Correction of images by linear interpolation in real space has allowed high-resolution structures to be calculated from cryo-EM images for symmetric particles. Here we describe and compare a simple real space method, a simple Fourier space method, and a somewhat more sophisticated Fourier space method to correct images for a measured anisotropy in magnification. Further, anisotropic magnification causes contrast transfer function (CTF) parameters estimated from image power spectra to have an apparent systematic astigmatism. To address this problem we develop an approach to adjust CTF parameters measured from distorted images so that they can be used with corrected images. The effect of anisotropic magnification on CTF parameters provides a simple way of detecting magnification anisotropy in cryo-EM datasets.
118632272
Multidimensionally-constrained relativistic mean-field models and potential-energy surfaces of actinide nuclei
Background: Many different shape degrees of freedom play crucial roles in determining the nuclear ground state and saddle point properties and the fission path. For the study of nuclear potential energy surfaces, it is desirable to have microscopic and self-consistent models in which all known important shape degrees of freedom are included. Purpose: By breaking both the axial and the spatial reflection symmetries simultaneously, we develop multidimensionally-constrained relativistic mean field (MDC-RMF) models. Methods: The nuclear shape is assumed to be invariant under the reversion of x and y axes, i.e., the intrinsic symmetry group is V-4 and all shape degrees of freedom beta(lambda mu) with even mu, such as beta(20), beta(22), beta(30), beta(32), beta(40), ..., are included self-consistently. The single-particle wave functions are expanded in an axially deformed harmonic oscillator (ADHO) basis. The RMF functional can be one of the following four forms: the meson exchange or point-coupling nucleon interactions combined with the nonlinear or density- dependent couplings. The pairing effects are taken into account with the BCS approach. Results: The one-, two, and three-dimensional potential energy surfaces of Pu-240 are illustrated for numerical checks and for the study of the effect of the triaxiality on the fission barriers. Potential energy curves of even-even actinide nuclei around the first and second fission barriers are studied systematically. Besides the first ones, the second fission barriers in these nuclei are also lowered considerably by the triaxial deformation. This lowering effect is independent of the effective interactions used in the RMF functionals. Further discussions are made about different predictions on the effect of the triaxiality between the macroscopic-microscopic and MDC-RMF models, possible discontinuities on PES's from self-consistent approaches, and the restoration of broken symmetries. Conclusions: MDC-RMF models give a reasonably good description of fission barriers of even-even actinide nuclei. It is important to include both the nonaxial and the reflection asymmetric shapes simultaneously for the study of potential energy surfaces and fission barriers of actinide nuclei and of those in unknown mass regions such as, e.g., superheavy nuclei.
92987620
Vertices, vortices & interacting surface operators
A bstractWe show that the vortex moduli space in non-abelian supersymmetric $ \mathcal{N} = \left( {{2},{2}} \right) $ gauge theories on the two dimensional plane with adjoint and anti-fundamental matter can be described as an holomorphic submanifold of the instanton moduli space in four dimensions. The vortex partition functions for these theories are computed via equivariant localization. We show that these coincide with the field theory limit of the topological vertex on the strip with boundary conditions corresponding to column diagrams. Moreover, we resum the field theory limit of the vertex partition functions in terms of generalized hypergeometric functions formulating their AGT dual description as interacting surface operators of simple type. Analogously we resum the topological open string amplitudes in terms of q-deformed generalized hypergeometric functions proving that they satisfy appropriate finite difference equations.
326670
Limits on sizes of fundamental particles and on gravitational mass of a scalar
We review the experimental limits on mass of excited fundamental particles and contact interaction energy scale parameters Λ for QCD, QED and electroweak reactions. In particular we have focused on the QED reaction measuring the differential cross-sections for the process e+e−→γγ(γ) at the energies from 91 GeV to 202 GeV using the data collected with the L3 detector from 1991 to 1999. With a global fit we set lower limits at 95% CL on Λ>1687 GeV, which restricts the characteristic QED size of the interaction region to Re<1.17×10−17 cm. All the interaction regions are found to be smaller than the Compton wavelength of the fundamental particles. This constraint is used to estimate a lower limit on the size of a fundamental particle related to gravitational interaction, applying the model of self-gravitating particle-like structure with the de Sitter vacuum core. It gives rτ⩾2.3×10−17 cm and re⩾1.5×10−18 cm, if leptons get masses at the electroweak scale, and rτ⩾3.3×10−27 cm,re⩾4.9×10−26 cm, as the most stri...
119135529
Orbifold Vortex and Super Liouville Theory
We study the nonabelian vortex counting problem on $\mathbb{C}/\mathbb{Z}_p$. At first we calculate vortex partition functions on the orbifold space using localization techniques, then we find how to extract orbifold vortex partitions function from orbifold linear quiver instanton partition functions. Finally, we study the AGT like relation between orbifold SU(2) vortices and $\mathcal{N} = 1$ super Liouville theory in the mixed R/NS sector by fixing the dictionary among parameters in the common hypergeometric functions system.