Dynamics of charged particles in a Penning trap

An automodel solution of self-consistent equations for an ellipsoidal cluster of Coulomb particles in a Penning trap is obtained.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 18–21, July, 1994.     

Parametric excitation of oscillations of charged particle bunches in a Penning trap

A self-similar solution is obtained for the self-consistent hydrodynamic equations describing the motion of an ellipsoid of charged particles in a Penning trap and in an rf trap. The conditions are determined for which a small periodic variation of the confining magnetic field in the Penning trap drives oscillations of the bunch. Zh. Tekh. Fiz. 67, 27–29 (January 1997)     

Production and investigation of multiply charged metal clusters in a Penning trap

Singly charged gold cluster ions from a laser-vaporization source are transferred into a Penning trap and subjected to electron bombardment. The charged reaction products are analyzed by time-of-flight mass spectrometry after axial ejection from the trap. They include singly charged cluster fragments, multiply charged clusters of the initial size and multiply charged cluster fragments. The multiply charged clusters are selected and further investigated by collision induced dissociation. Two types of reactions can be distinguished: Dissociation into several charged fragments and evaporation of neutrals. Several features of multiply charged clusters relevant for future investigations are reviewed.This work comprises part of the dissertation of J. Ziegler.     

Operation of a planar Penning trap

We demonstrate experimentally the confinement of electrons in a novel planar Penning trap. Measurement of the eigenfrequencies of the trapped electron cloud exhibits similar behaviour as in conventional 3-dimensional penning traps. The trap may be of future use in quantum computing schemes using single cold electrons.     

Motional frequencies in a planar Penning trap

A Penning trap consisting of concentric ring electrodes on a substrate and a magnetic field perpendicular to the substrate plane has been loaded with electrons. In order to demonstrate the performance of the trap we have measured the motional frequencies of the trapped electrons. Frequencies, line shape and width agree well with simulations. Miniaturization of the device is at hand which opens novel possibilities for application in quantum computing. Contribution presented at the TCP06, Vancouver Island, 2006-09-21     

Formation of fullerene dianions in a Penning trap

Fullerene dianions in the range C₇₀^2- to C₉₀^2- have been created by subjecting trapped fullerene monoanions to low energy electrons in a Penning trap. The dianion production was found to be a function of the trapping-potential depth and the time of interaction between the simultaneously stored monoanions and electrons. Under similar conditions the dianion yield depends on the size of the fullerenes with more than 10% of the trapped C₉₀^- ions forming dianions while the corresponding relative yield for C₇₀^2- was less than 0.1%. The large difference can be explained by the repulsive Coulomb barrier and the second electron affinity of the fullerenes.     

Adiabatic cooling of antiprotons in a Penning trap

An antiproton cloud cooled at 4.2 K in a Penning trap can be further cooled by adiabatic reduction of the trap magnetic and electric fields. It will be shown that the temperature can be reduced by two orders of magnitude. This cooling method may be useful to obtain ultra-low energy antiprotons for the measurement of their gravitational properties and the production of ultra-low energy antihydrogen atoms.     

A Penning trap for g-factor measurements in highly charged ions by laser-microwave double-resonance spectroscopy

Precise determination of bound-electron g-factors in heavy highly-charged ions (e.g. Bi^82?+?, U^91?+?) provides a stringent test of bound-state QED in extreme fields. With a laser-microwave double-resonance technique we will probe the microwave transitions between the Zeeman sub-levels of the hyperfine structure in highly charged ions. From this the bound electron g-factor g_J can be determined. We present the experimental progress of this novel method to measure the g-factor of the bound electron in highly charged ions.     

Cooling of short-lived, radioactive, highly charged ions with the TITAN cooler Penning trap

TITAN is an on-line facility dedicated to precision experiments with short-lived radioactive isotopes, in particular mass measurements. The achievable resolution on mass measurement, which depends on the excitation time, is limited by the half life of the radioactive ion. One way to bypass this is by increasing the charge state of the ion of interest. TITAN has the unique capability of charge-breeding radioactive ions using an electron-beam ion trap (EBIT) in combination with Penning trap mass spectrometry. However, the breeding process leads to an increase in energy spread, ??E, which in turn negatively influences the mass uncertainty. We report on the development of a cooler Penning trap which aims at reducing the energy spread of the highly charged ions prior to injection into the precision mass measurement trap. Electron and proton cooling will be tested as possible routes. Mass selective cooling techniques are also envisioned.     

Determination of the helium-4 mass in a Penning trap

The determination of the rotational quadrupole alignment of diatomic molecules via REMPI detection is investigated. In this process a high focal intensity usually increases the detection probability. At high intensities the AC Stark effect may cause a splitting of the normally degenerate m_J sublevels of a rotational state J beyond the spectral width of the exciting radiation. This leads to a selective detection of only certain m_J states with the consequence that deduced alignment factors can be misleading. From the theoretical considerations line profiles are explicitly calculated for dynamic polarizabilities which represent the B ¹Σ⁺ _u←X ¹Σ⁺ _g transition of H₂, in order to fit an experimental (3+1) REMPI spectrum and to predict (1+1') line shapes as a function of laser intensity. It is further shown that the deduced quadrupole alignment factor A ₀ ⁽²⁾ is significantly changed by the second order AC Stark effect when the intensities are chosen high enough to observe asymmetric broadened line profiles. Different combinations of relative linear polarizations of the exciting and ionizing laser beams are discussed. Received 1st August 2000 and Received in final form 2 May 2001     

Instabilities of an electron cloud in a Penning trap

We have measured the storage instabilities of electrons in a Penning trap at low magnetic fields. These measurements are carried out as a function of the trapping voltage, for different magnetic fields. It is seen that these instabilities occur at the same positions when the trapping voltage is expressed as a percentage of the maximum voltage, given by the stability limit. The characteristic frequencies at which these instabilities occur, obey a relation that is given by n _zω _z + n ₊ω ₊ + n _-ω _- = 0, where ω _z, ω ₊ and ω _- are the axial, perturbed cyclotron and the magnetron frequencies of the trapped electrons respectively, and the n's are integers. The reason for these instabilities are attributed to higher order static perturbations in the trapping potential. Received 5 August 2002 / Received in final form 14 October 2002 Published online 17 December 2002 RID="a" ID="a"Present address: Dept. of Physics, Rampurhat College, Rampurhat, Birbhum, West Bengal, India. RID="b" ID="b"e-mail: werth@mail.uni-mainz.de     

Solitary waves in a long structure of charged particles confined in the linear Paul trap

This paper demonstrates the possibility of generation of density waves in the form of individual humps in a long structure of the one-component Coulomb system of dust particles confined in the linear Paul traps in air under normal conditions Our numerical simulations by particle-in-cell method support this possibility. Physical possibility of analogous the hump density waves (caustics) is discussed by V.I. Arnold in his book ‘Catastrophe Theory’ and is caused by the nonuniform velocity distribution of dust particles.     

Half-open Penning trap with efficient light collection for precision laser spectroscopy of highly charged ions

We have conceived, built and operated a ’half-open’ cylindrical Penning trap for the confinement and laser spectroscopy of highly charged ions. This trap allows fluorescence detection employing a solid angle which is about one order of magnitude larger than in conventional cylindrical Penning traps. At the same time, the desired electrostatic and magnetostatic properties of a closed-endcap cylindrical Penning trap are preserved in this configuration. We give a detailed account on the design and confinement properties, a characterization of the trap and show first results of light collection with in-trap produced highly charged ions.     

Temperature measurement of a single ion in a Penning trap

The present work is concerned with the association of a temperature to a single ion stored in a Penning ion trap. Several methods are described which allow to determine the temperature by measurements of the ions cyclotron and axial trapping frequencies. Recent results of a measurement on a hydrogen-like carbon ion ¹²C^{5 +} by use of mode coupling are presented and possible further applications are discussed.Received: 8 July 2004, Published online: 6 December 2004PACS: 07.20.-n. Thermal instruments and apparatus - 07.20.Dt. Thermometers - 42.50.Lc Quantum fluctuations - 42.50.Vk Mechanical effects of light on ions     

Status of the Penning trap project in Munich

The MLLTRAP at the Maier-Leibnitz-Laboratory (Garching) is a new Penning trap facility designed to combine several novel technologies to decelerate, charge breed, cool, bunch and purify the reaction products and perform high-accuracy nuclear and atomic mass measurements. It is now in the commissioning phase, achieving a mass-resolving power of about 10⁵ in the purification trap for stable ions.     

Analysis of the merger between plasma vortices in a Penning trap

In the paper, the interaction between a finite-size vortex of constant density and a weak, pointlike vortex in a Penning trap is studied analytically. A suitable Fourier representation for the contour of the finite vortex is considered and a model for small perturbations, which is linear with respect to the Fourier coefficients, is deduced. The resonance condition for the surface modes and a sufficient condition for the merger of the vortices not to occur are obtained. The validity of the analytic results is checked with a contour dynamics code making use of a new methodology developed by the authors. Numerical results referred to a case of strongly-interacting vortices are also reported.Received: 18 April 2003, Published online: 12 August 2003PACS: 52.27.Jt Nonneutral plasmas - 52.35.We Plasma vorticity - 47.32.Cc Vortex dynamicsA. DAngola: Present address: Universitá della Basilicata, Dipartimento di Ingegneria e Fisica dellambiente, Contrada Macchia Romana, 85100 Potenza, Italy.