4,786 research outputs found
Heavy ion plasma confinement in an RF quadrupole trap
The confinement of an electron free plasma in a pure quadrupole RF electric trap was considered. The ultimate goal was to produce a large density of mercury ions, in order to realize a trapped ion frequency standard using the hyperfine resonance of 199 Hg(+) at 40.7 GHz. An attempt was made to obtain an iodine plasma consisting of equal numbers of positive and negative ions of atomic iodine, the positive iodine ions, being susceptible to charge-exchange with mercury atoms, will produce the desired mercury ions. The experiment showed that the photoproduction of ions pairs in iodine using the necessary UV radiation occurs with a small cross-section, making it difficult to demonstrate the feasibility of space charge neutralization in a quadrupole trap. For this reason it was considered expedient to choose thallium iodide, which has a more favorable absorption spectrum (in the region of 2000 to 2100 A). The results indicate that, although the ionic recombination is a serious limiting factor, a considerable improvement can be obtained in practice for the density of trapped ions, with a considerable advantage in lifetimes for spectroscopic purposes. The ion pair formation by photoionization is briefly reviewed
The Electrostatic Ion Beam Trap : a mass spectrometer of infinite mass range
We study the ions dynamics inside an Electrostatic Ion Beam Trap (EIBT) and
show that the stability of the trapping is ruled by a Hill's equation. This
unexpectedly demonstrates that an EIBT, in the reference frame of the ions
works very similar to a quadrupole trap. The parallelism between these two
kinds of traps is illustrated by comparing experimental and theoretical
stability diagrams of the EIBT. The main difference with quadrupole traps is
that the stability depends only on the ratio of the acceleration and trapping
electrostatic potentials, not on the mass nor the charge of the ions. All kinds
of ions can be trapped simultaneously and since parametric resonances are
proportional to the square root of the charge/mass ratio the EIBT can be used
as a mass spectrometer of infinite mass range
A Three Dimensional Lattice of Ion Traps
We propose an ion trap configuration such that individual traps can be
stacked together in a three dimensional simple cubic arrangement. The isolated
trap as well as the extended array of ion traps are characterized for different
locations in the lattice, illustrating the robustness of the lattice of traps
concept. Ease in the addressing of ions at each lattice site, individually or
simultaneously, makes this system naturally suitable for a number of
experiments. Application of this trap to precision spectroscopy, quantum
information processing and the study of few particle interacting system are
discussed.Comment: 4 pages, 4 Figures. Fig 1 appears as a composite of 1a, 1b, 1c and
1d. Fig 2 appears as a composite of 2a, 2b and 2
Evidence of sympathetic cooling of Na+ ions by a Na MOT in a hybrid trap
A hybrid ion-neutral trap provides an ideal system to study collisional
dynamics between ions and neutrals. This system provides a general cooling
method that can be applied to optically inaccessible species and can also
potentially cool internal degrees of freedom. The long range polarization
potentials () between ions and neutrals result in large
scattering cross sections at cold temperatures, making the hybrid trap a
favorable system for efficient sympathetic cooling of ions by collisions with
neutral atoms. We present experimental evidence of sympathetic cooling in a
hybrid trap of \ce{Na+} ions, which are closed shell and therefore do not have
a laser induced atomic transition, by equal mass cold Na atoms in a
magneto-optical trap (MOT).Comment: 7 figure
Quantum Dynamics without the Wave Function
When suitably generalized and interpreted, the path-integral offers an
alternative to the more familiar quantal formalism based on state-vectors,
selfadjoint operators, and external observers. Mathematically one generalizes
the path-integral-as-propagator to a {\it quantal measure} on the space
of all ``conceivable worlds'', and this generalized measure expresses
the dynamics or law of motion of the theory, much as Wiener measure expresses
the dynamics of Brownian motion. Within such ``histories-based'' schemes new,
and more ``realistic'' possibilities open up for resolving the philosophical
problems of the state-vector formalism. In particular, one can dispense with
the need for external agents by locating the predictive content of in its
sets of measure zero: such sets are to be ``precluded''. But unrestricted
application of this rule engenders contradictions. One possible response would
remove the contradictions by circumscribing the application of the preclusion
concept. Another response, more in the tradition of ``quantum logic'', would
accommodate the contradictions by dualizing to a space of
``co-events'' and effectively identifying reality with an element of this dual
space.Comment: plainTeX, 24 pages, no figures. To appear in a special volume of {\it
Journal of Physics A: Mathematical and General} entitled ``The Quantum
Universe'' and dedicated to Giancarlo Ghirardi on the occasion of his 70th
birthday. Most current version is available at
http://www.physics.syr.edu/~sorkin/some.papers/ (or wherever my home-page may
be
Simple microwave field imaging technique using hot atomic vapor cells
We demonstrate a simple technique for microwave field imaging using alkali
atoms in a vapor cell. The microwave field to be measured drives Rabi
oscillations on atomic hyperfine transitions, which are detected in a spatially
resolved way using a laser beam and a camera. Our vapor cell geometry enables
single-shot recording of two-dimensional microwave field images with 350 {\mu}m
spatial resolution. Using microfabricated vapor cell arrays, a resolution of a
few micrometers seems feasible. All vector components of the microwave magnetic
field can be imaged. Our apparatus is simple and compact and does not require
cryogenics or ultra-high vacuum
About the dynamics and thermodynamics of trapped ions
This tutorial introduces the dynamics of charged particles in a
radiofrequency trap in a very general manner to point out the differences
between the dynamics in a quadrupole and in a multipole trap. When dense
samples are trapped, the dynamics is modified by the Coulomb repulsion between
ions. To take into account this repulsion, we propose to use a method,
originally developed for particles in Penning trap, that model the ion cloud as
a cold fluid. This method can not reproduce the organisation of cold clouds as
crystals but it allows one to scale the size of large samples with the trapping
parameters and the number of ions trapped, for different linear geometries of
trap.Comment: accepted for publication in the "Modern Applications of Trapped Ions"
special issu
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