A New Concept for Time-of-Flight Mass Spectrometry with Slowed-down Short-Lived Isotopes

A new concept for direct mass measurements of short-lived nuclei with an electrostatic time-of-flight mass spectrometer is described. The spectrometer can be coupled to an in-flight separator such as SHIP or FRS via a gas stopping cell and a gas-filled linear Paul trap. The time required for mass measurement is of the order of a few milliseconds allowing one to investigate nuclei with these short half-lives. A mass-resolving-power m/Δm _FWHM=50 000 has been reached. First results of the range-focusing technique are presented, which is under development for the efficient stopping and extraction of relativistic exotic nuclei. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Influence of Proton Irradiation on Properties of Glass with ITO Coating

Optics and Spectroscopy - Changes in the surface morphology and optical properties of the samples of K208 glass with an ITO film are studied after the effect of protons with an energy of 20 keV and...     

Approximation of the Jacobian matrix in (m, 3)-methods of solving stiff systems

A theorem is proved which states that the maximal order of accuracy in L-stable (m, k)-methods with Jacobian matrix freezing is equal to four.     

Formation of the double addition products of donor-acceptor cyclopropanes with 2-pyrazolines in the presence of Lewis acids

A reaction of excess of cyclopropane-1,1-dicarboxylates substituted at position 2 with 2-pyrazolines in the presence of 3 equiv. of GaCl₃ at 5 °C selectively resulted in the cyclopropanes double addition products, viz., N-substituted 1,2-diazabicyclo[3.3.0]octanes. In this case, the first molecule of the starting cyclopropane formed the bicyclic system, whereas the second added at the N-H bond of the adduct formed. When catalytic amount of Sc(OTf)₃ was used in this reaction instead of GaCl₃ at 40 °C, besides the corresponding 1,2-diazabicyclo[3.3.0]-octanes, another type of cyclopropane double addition products, viz., N-alkyl-2-pyrazolines, was formed, in which the alkyl chain was assembled from two molecules of the starting cyclopropane. A plausible mechanism for the transformations observed was suggested.     

4-Phenylspiro[2.2]pentane-1,1-dicarboxylate: synthesis and reactions with EtAlCl2 and 4,5-diazaspiro[2.4]hept-4-ene derivative

1. Download : Download high-res image (79KB)
2. Download : Download full-size image

     

Feeble Fish in Time-Dependent Waters and Homogenization of the G-equation

We study the following control problem. A fish with bounded aquatic locomotion speed swims in fast waters. Can this fish, under reasonable assumptions, get to a desired destination? It can, even if the flow is time dependent. Moreover, given a prescribed sufficiently large time t , it can be there at exactly the time t . The major difference from our previous work is the time dependence of the flow. We also give an application to homogenization of the G-equation. © 2019 Wiley Periodicals, Inc.     

On the Branching Ratios of the B0 → J/ψη(η′, π0) and Bs → J/ψη(η′) Decays

JETP Letters - We developed phenomenological approach that successfully describes experimental data on the branching ratio of B-meson decays with production of η(η′) mesons.