2,218 research outputs found
Isochronicity Correction in the CR Storage Ring
A challenge for nuclear physics is to measure masses of exotic nuclei up to
the limits of nuclear existence which are characterized by low production cross
sections and short half-lives. The large acceptance Collector Ring (CR) at FAIR
tuned in the isochronous ion-optical mode offers unique possibilities for
measuring short-lived and very exotic nuclides. However, in a ring designed for
maximal acceptance, many factors limit the resolution. One point is a limit in
time resolution inversely proportional to the transverse emittance. But most of
the time aberrations can be corrected and others become small for large number
of turns. We show the relations of the time correction to the corresponding
transverse focusing and that the main correction for large emittance
corresponds directly to the chromaticity correction for transverse focusing of
the beam. With the help of Monte-Carlo simulations for the full acceptance we
demonstrate how to correct the revolution times so that in principle
resolutions of dm/m=1E-6 can be achieved. In these calculations the influence
of magnet inhomogeneities and extended fringe fields are considered and a
calibration scheme also for ions with different mass-to-charge ratio is
presented.Comment: 6 figures, recised version May 201
Diels-Alder adduct isomerization studies using DSC and PMR methods
Model Diels-Alder (D-A) adducts of a different isomeric composition were synthesized using furfuryl acetate (FA) and maleimid (MI). The composition of synthesized isomers was analyzed using the proton-magnetic resonance method (PMR). The D-A adduct isomerization process was studied using the differential scanning calorimetry (DSC) method in the nonisothermal mode
Conceptual design of elliptical cavities for intensity and position sensitive beam measurements in storage rings
Position sensitive beam monitors are indispensable for the beam diagnostics
in storage rings. Apart from their applications in the measurements of beam
parameters, they can be used in non-destructive in-ring decay studies of
radioactive ion beams as well as enhancing precision in the isochronous mass
measurement technique. In this work, we introduce a novel approach based on
cavities with elliptical cross-section, in order to compensate for existing
limitations in ion storage rings. The design is aimed primarily for future
heavy ion storage rings of the FAIR project. The conceptual design is discussed
together with simulation results.Comment: Added definition of Uv and Pdiss in the introduction section. Added
Mode numbering in table 1 and figure 1 for more clarity. Corrected one wrong
figure reference. Other minor typo correction
Cyclic projectors and separation theorems in idempotent convex geometry
Semimodules over idempotent semirings like the max-plus or tropical semiring
have much in common with convex cones. This analogy is particularly apparent in
the case of subsemimodules of the n-fold cartesian product of the max-plus
semiring it is known that one can separate a vector from a closed subsemimodule
that does not contain it. We establish here a more general separation theorem,
which applies to any finite collection of closed semimodules with a trivial
intersection. In order to prove this theorem, we investigate the spectral
properties of certain nonlinear operators called here idempotent cyclic
projectors. These are idempotent analogues of the cyclic nearest-point
projections known in convex analysis. The spectrum of idempotent cyclic
projectors is characterized in terms of a suitable extension of Hilbert's
projective metric. We deduce as a corollary of our main results the idempotent
analogue of Helly's theorem.Comment: 20 pages, 1 figur
On differential equation on four-point correlation function in the Conformal Toda Field Theory
The properties of completely degenerate fields in the Conformal Toda Field
Theory are studied. It is shown that a generic four-point correlation function
that contains only one such field does not satisfy ordinary differential
equation in contrast to the Liouville Field Theory. Some additional assumptions
for other fields are required. Under these assumptions we write such a
differential equation and solve it explicitly. We use the fusion properties of
the operator algebra to derive a special set of three-point correlation
function. The result agrees with the semiclassical calculations.Comment: 5 page
Observation of Non-Exponential Orbital Electron Capture Decays of Hydrogen-Like Pr and Pm Ions
We report on time-modulated two-body weak decays observed in the orbital
electron capture of hydrogen-like Pr and Pm
ions coasting in an ion storage ring. Using non-destructive single ion,
time-resolved Schottky mass spectrometry we found that the expected exponential
decay is modulated in time with a modulation period of about 7 seconds for both
systems. Tentatively this observation is attributed to the coherent
superposition of finite mass eigenstates of the electron neutrinos from the
weak decay into a two-body final state.Comment: 12 pages, 5 figure
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