Search results for " Ring"
showing 10 items of 478 documents
Associative rings whose adjoint semigroup is locally nilpotent
2001
The set of all elements of an associative ring R, not necessarily with a unit element, forms a semigroup R ad under the circle operation \({r\circ s}={r+s+rs}\) on R. The ring R is called radical if R ad is a group. It is proved that the semigroup R ad is nilpotent of class n (in sense of A. Mal'cev or B. H. Neumann and T. Taylor) if and only if the ring R is Lie-nilpotent of class n. This yields a positive answer to a question posed by A. Krasil'nikov and independently considered by D. Riley and V. Tasic. It is also shown that the adjoint group of a radical ring R is locally nilpotent if and only if R is locally Lie-nilpotent.
Relatively Orthocomplemented Skew Nearlattices in Rickart Rings
2015
AbstractA class of (right) Rickart rings, called strong, is isolated. In particular, every Rickart *-ring is strong. It is shown in the paper that every strong Rickart ring R admits a binary operation which turns R into a right normal band having an upper bound property with respect to its natural order ≤; such bands are known as right normal skew nearlattices. The poset (R, ≤) is relatively orthocomplemented; in particular, every initial segment in it is orthomodular.The order ≤ is actually a version of the so called right-star order. The one-sided star orders are well-investigated for matrices and recently have been generalized to bounded linear Hilbert space operators and to abstract Ric…
Towards laser cooling of fast Be+ ions in the storage ring TSR
1989
Publisher Summary This chapter presents a clear understanding of laser-ion interactions under storage ring conditions to prepare the basis of laser cooling of fast-stored ion beams. In addition, the method of laser-induced fluorescence provides precise data for beam properties such as absolute velocity, momentum spread, and lifetime. 9Be+ ions stored in a heavy-ion storage ring are a promising species for laser cooling down to temperatures several orders of magnitude less than those reached for protons by electron cooling at the Novosibirsk ring. Short cooling times and microkelvin temperatures can be envisaged, where the structure of the ion beam is dominated by Coulomb repulsion. The chap…
SPARC experiments at the high-energy storage ring
2013
The physics program of the SPARC collaboration at the Facility for Antiproton and Ion Research (FAIR) focuses on the study of collision phenomena in strong and even extreme electromagnetic fields and on the fundamental interactions between electrons and heavy nuclei up to bare uranium. Here we give a short overview on the challenging physics opportunities of the high-energy storage ring at FAIR for future experiments with heavy-ion beams at relativistic energies with particular emphasis on the basic beam properties to be expected.
First attempt of the measurement of the beam polarization at an accelerator with the optical electron polarimeter POLO
2005
The conventional methods for measuring the polarization of electron beams are either time consuming, invasive or accurate only to a few percent. We developped a method to measure electron beam polarization by observing the light emitted by argon atoms following their excitation by the impact of polarized electrons. The degree of circular polarization of the emitted fluorescence is directly related to the electron polarization. We tested the polarimeter on a test GaAs source available at the MAMI electron accelerator in Mainz, Germany. The polarimeter determines the polarization of a 50 keV electron beam decelerated to a few eV and interacting with an effusive argon gas jet. The resulting de…
Optimization of the Electron Emission From Carbon Nanotubes for Electron Cooling in ELENA
2021
Electron cooling is a process that guarantees beam quality in low energy antimatter facilities. In ELENA the electron cooler allows to reduce the emittance blow-up of the antiproton beam, thus delivering highly focused and bright beams at the unprecedented low energy of 100 keV to the experiments. In order to have a "cold" beam at such low energy, the electron gun of the cooler must emit a monoenergetic and relatively intense electron beam. Simulations have shown that efficient cooling can be achieved with a 5 mA electron beam having transverse energy spread of less than 100 meV and longitudinal energy spread of about 1 meV. A thermionic gun is currently used in operation, although it limit…
Parameterization of a comprehensive explicit model for single-ring infiltration
2021
International audience; Comprehensive infiltration models can simultaneously describe transient and steady-state infiltration behaviors, and therefore can be applied to a range of experimental conditions. However, satisfactory model accuracy re- quires proper parameterization, including estimating the transition time from transient to steady-state flow conditions (τcrit). This study focused on improving the estimation of two parameters – τcrit and a second constant called a – used in a comprehensive, explicit, two-term model for single ring infiltration (hereafter referred to as the SA model). Different studies have recommended that a should be as low as 0.45 to as high as 0.91. Furthermore…
Integrable systems and moduli spaces of curves
2016
This document has the purpose of presenting in an organic way my research on integrable systems originating from the geometry of moduli spaces of curves, with applications to Gromov-Witten theory and mirror symmetry. The text contains a short introduction to the main ideas and prerequisites of the subject from geometry and mathematical physics, followed by a synthetic review of some of my papers (listed below) starting from my PhD thesis (October 2008), and with some open questions and future developements. My results include: • the triple mirror symmetry among P 1-orbifolds with positive Euler characteristic , the Landau-Ginzburg model with superpotential −xyz + x p + y q + z r with 1 p + …
Self-dual modules over local rings of curve singularities
2006
Abstract Let C be a reduced curve singularity. C is called of finite self-dual type if there exist only finitely many isomorphism classes of indecomposable, self-dual, torsion-free modules over the local ring of C . In this paper it is shown that the singularities of finite self-dual type are those which dominate a simple plane singularity.
LSOM: A Link State protocol Over MAC addresses for metropolitan backbones using Optical Ethernet switches
2003
This paper presents a new protocol named "Link State Over MAC" (LSOM) for Optical Ethernet switches to allow the use of active loop topologies, like meshes, in Metropolitan Area Networks (MAN) or even Wide Area Networks (WAN) backbone. In this respect, LSOM is an alternative to a ring topology as proposed in draft IEEE 802.17 Resilient Packet Ring (RPR) or a tree topology using IEEE802. 1D Rapid Spanning Tree Protocol (RSTP). LSOM provides higher scalability and is able to achieve better bandwidth utilization and lower latency than RSTP and RPR. Simulation results for 4-node and 9-node topologies show that LSOM can improve throughput over RPR by a factor of up to 1.7. Furthermore, full free…