1,278 research outputs found
Penning traps as a versatile tool for precise experiments in fundamental physics
This review article describes the trapping of charged particles. The main
principles of electromagnetic confinement of various species from elementary
particles to heavy atoms are briefly described. The preparation and
manipulation with trapped single particles, as well as methods of frequency
measurements, providing unprecedented precision, are discussed. Unique
applications of Penning traps in fundamental physics are presented.
Ultra-precise trap-measurements of masses and magnetic moments of elementary
particles (electrons, positrons, protons and antiprotons) confirm
CPT-conservation, and allow accurate determination of the fine-structure
constant alpha and other fundamental constants. This together with the
information on the unitarity of the quark-mixing matrix, derived from the
trap-measurements of atomic masses, serves for assessment of the Standard Model
of the physics world. Direct mass measurements of nuclides targeted to some
advanced problems of astrophysics and nuclear physics are also presented
The Ramsey method in high-precision mass spectrometry with Penning traps: Experimental results
The highest precision in direct mass measurements is obtained with Penning
trap mass spectrometry. Most experiments use the interconversion of the
magnetron and cyclotron motional modes of the stored ion due to excitation by
external radiofrequency-quadrupole fields. In this work a new excitation
scheme, Ramsey's method of time-separated oscillatory fields, has been
successfully tested. It has been shown to reduce significantly the uncertainty
in the determination of the cyclotron frequency and thus of the ion mass of
interest. The theoretical description of the ion motion excited with Ramsey's
method in a Penning trap and subsequently the calculation of the resonance line
shapes for different excitation times, pulse structures, and detunings of the
quadrupole field has been carried out in a quantum mechanical framework and is
discussed in detail in the preceding article in this journal by M. Kretzschmar.
Here, the new excitation technique has been applied with the ISOLTRAP mass
spectrometer at ISOLDE/CERN for mass measurements on stable as well as
short-lived nuclides. The experimental resonances are in agreement with the
theoretical predictions and a precision gain close to a factor of four was
achieved compared to the use of the conventional excitation technique.Comment: 12 pages, 14 figures, 2 table
High-accuracy Penning trap mass measurements with stored and cooled exotic ions
The technique of Penning trap mass spectrometry is briefly reviewed
particularly in view of precision experiments on unstable nuclei, performed at
different facilities worldwide. Selected examples of recent results emphasize
the importance of high-precision mass measurements in various fields of
physics
Relation Between a Three Parameter Formula for Isotope Shifts and Staggering Parameters
It is noted that the staggering parameters used to describe even-odd effects
for isotope shifts can in some cases exhibit very rapidly varying behavior as a
function of neutron number. On the other hand a three parameter formula (3P)
with fixed coefficients can explain the same behaviour
Robustness of spatial Penning trap modes against environment-assisted entanglement
The separability of the spatial modes of a charged particle in a Penning trap
in the presence of an environment is studied by means of the positive partial
transpose (PPT) criterion. Assuming a weak Markovian environment, described by
linear Lindblad operators, our results strongly suggest that the environmental
coupling of the axial and cyclotron degrees of freedom does not lead to
entanglement at experimentally realistic temperatures. We therefore argue that,
apart from unavoidable decoherence, the presence of such an environment does
not alter the effectiveness of recently suggested quantum information protocols
in Penning traps, which are based on the combination of a spatial mode with the
spin of the particle.Comment: 11 pages, 2 figure
Emergent Collectivity in Nuclei and Enhanced Proton-Neutron Interactions
Enhanced proton-neutron interactions occur in heavy nuclei along a trajectory
of approximately equal numbers of valence protons and neutrons. This is also
closely aligned with the trajectory of the saturation of quadrupole
deformation. The origin of these enhanced p-n interactions is discussed in
terms of spatial overlaps of proton and neutron wave functions that are
orbit-dependent. It is suggested for the first time that nuclear collectivity
is driven by synchronized filling of protons and neutrons with orbitals having
parallel spins, identical orbital and total angular momenta projections,
belonging to adjacent major shells and differing by one quantum of excitation
along the z-axis. These results may lead to a new approach to symmetry-based
theoretical calculations for heavy nuclei.Comment: 6 pages, 4 figure
Observation of Spin Flips with a Single Trapped Proton
Radio-frequency induced spin transitions of one individual proton are
observed for the first time. The spin quantum jumps are detected via the
continuous Stern-Gerlach effect, which is used in an experiment with a single
proton stored in a cryogenic Penning trap. This is an important milestone
towards a direct high-precision measurement of the magnetic moment of the
proton and a new test of the matter-antimatter symmetry in the baryon sector
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