Evaporative cooling and coherent axial oscillations of highly charged ions in a penning trap

Externally, in an electron beam ion trap, generated Ar16+ ions were retrapped in a Penning trap and evaporatively cooled in their axial motion. The cooling was observed by a novel extraction technique based on the excitation of a coherent axial oscillation which yields short ion bunches of well-defined energies. The initial temperature of the ion cloud was decreased by a factor of more than 140 within 1?s, while the phase-space density of the coldest extracted ion pulses was increased by a factor of up to about 9.     

Production of highly charged argon ions from a room temperature electron beam ion trap

In this work, highly charged ions have been extracted from the advanced Electron Beam Ion Source (EBIS-A) developed in a scientific cooperation between the Dresden University of Technology and the DREEBIT GmbH Dresden. The charge state distributions of ions extracted from the EBIS-A are measured in the pulse and leaky modes under different operation conditions. Ar¹⁶⁺ ions with current of 2 pA are produced and extracted in the leaky mode. 3×10⁵ Ar¹⁸⁺ ions per pulse are extracted in the pulse mode. The ion charge state distribution is a     

Production of highly charged argon ions from a room temperature electron beam ion trap

In this work.highly charged ions have been extracted from the advanced Electron Beam Ion Source (EBIS-A) developed in a scientific cooperation between the Dresden University of Technology and the DREEBIT GmbH Dresden.The charge state distributions of ions extracted from the EBIS-A are measured in and extracted in the leaky mode.3×105 Ar18+ ions per pulse are extracted in the pulse mode.The ion charge state distribution is a function of the ionization time.     

PENTATRAP: a novel cryogenic multi-Penning-trap experiment for high-precision mass measurements on highly charged ions

The novel five-Penning-trap mass spectrometer Pentatrap is developed at the Max-Planck-Institut für Kernphysik (MPIK), Heidelberg. Ions of interest are long-lived highly charged nuclides up to bare uranium. Pentatrap aims for an accuracy of a few parts in 10¹² for mass ratios of mass doublets. A physics program for Pentatrap includes Q-value measurements of β-transitions relevant for neutrino physics, stringent tests of quantum electrodynamics in the regime of extreme electric fields, and a test of special relativity. Main features of Pentatrap are an access to a source of highly charged ions, a multi-trap configuration, simultaneous measurements of frequencies, a continuous precise monitoring of magnetic field fluctuations, a fast exchange between different ions, and a highly sensitive cryogenic non-destructive detection system. This article gives a motivation for the new mass spectrometer Pentatrap, presents its experimental setup, and describes the present status.     

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.     

电子束离子阱中高价态离子演化过程的数值模拟

讨论了电子束离子阱(EBIT)中决定高价态离子演化过程的主要物理机制.对EBIT中高价态离 子的演化过程进行了详细的数值计算并与实验进行了比较.讨论了EBIT各种不同的运行参数 对平衡时高价态离子相对丰度和温度的影响. 关键词： 电子束离子阱 高价态离子 数值模拟     

Paul阱中一维两离子系统的能带结构

利用熟知的级数截断方法，设计数值程序计算了线形Paul阱中库仑关联的两离子系统Schrdinger方程的精确解，得到接近目前离子阱实验能够实现的阱频下系统分立的运动态波函数和能谱，它们对应于阱频值的一个无穷可数的点集.在该点集内两相邻点之间连续变化阱频，由量子微扰法得到以精确分立谱为基础的能带结构，包括较宽的能隙和较窄的带宽.能带结构的存在将影响以该系统为基础的量子逻辑操作和激光边带冷却等问题，应该在实验研究中加以考虑.     

Resonant electron impact excitation of highly charged Fe ions studied with a compact electron beam ion trap

We present extreme ultraviolet spectra of 3s3p–3s3d transitions in Fe¹⁴⁺ observed with a compact electron beam ion trap. The contributions of indirect excitation via a metastable state and resonant excitation are studied by observing the electron energy dependence of the spectra for the energy range of 60–210 eV. The results indicate that the 3s3d ¹D₂ level is directly excited from the 3s² ground state whereas the 3s3d ³D₃ level has a large contribution of the indirect excitation via the 3s3p ³P₂ metastable state. Comparisons with the theoretical excitation cross sections including MNn resonant excitations show good qualitative agreement with the experimental results for the electron energy dependent features.     

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.     

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.     

Axial resonances of Ar + ions observed in a linear Paul trap

Non-neutral plasmas composed of 10⁶ to 10⁷ Ar⁺ ions were confined in a linear Paul trap which had a non-harmonic electrostatic potential in axial direction. Axial resonances were observed by applying additional RF electric field and detecting axially ejected ions. It was found that the resonance frequencies shifted as a function of the ion number, the amplitude of additional RF electric field, and the applied electrostatic potential for the axial confinement.      

Beta decay of highly charged ions

Ion storage rings and ion traps provide the very first opportunity to address nuclear beta decay under conditions prevailing in hot stellar plasmas during nucleosynthesis, i.e. at high atomic charge states. Experiments are summarized that were performed in this field during the last decade at the ion storage-cooler ring ESR in Darmstadt. Special emphasis is given to the first observation of bound-state beta decay, where the created electron remains bound in an inner orbital of the daughter atom. The impact of this specific ‘stellar’ decay mode for s-process nucleosynthesis as well as for nuclear ‘eon clocks’ is outlined. Finally, a new technique, single-ion decay spectroscopy, is presented, where one observes two-body beta decay characteristics (i.e. orbital electron capture or bound-state beta decay) of highly charged, single ions for well-defined nuclear and atomic quantum states of both the mother – and the daughter – ion.     

Hyperfine structure of highly charged ions

¹⁹⁷Au Mössbauer spectra from Au/TM (TM = Fe, Co, Ni) multilayers consist mainly of two components. One component shows a large hyperfine magnetic field due to the hybridization at the interface between Au and ferromagnetic layers. The other component is nonmagnetic arising from the middle part of the Au layers. From the fractional area of the magnetic components in each spectrum, the Au atoms in 0.4 nm Au layers are perturbed by the Fe and Ni layers, and Co layers perturb 0.3 nm Au layers at the interface.     

Paul 阱中共面三离子的量子力学问题

对Paul阱中共面三离子体系作了研究,通过分析其总角动量L=2时的情形单体密度和形状密度,确定了体系的结构和内部运动情况,并与总角动量L=0和经典情形进行了比较。     

Structure and dynamics of highly charged heavy ions studied with the electron beam ion trap in Tokyo

In this paper, we present the structure and the dynamics of highly charged heavy ions studied through dielectronic recombination (DR) observations performed with the Tokyo electron beam ion trap. By measuring the energy dependence of the ion abundance ratio in the trap at equilibrium, we have observed DR processes for open shell systems very clearly. Remarkable relativistic effects due to the generalized Breit interaction have been clearly shown in DR for highly charged heavy ions. We also present the first result for the coincidence measurement of two photons emitted from a single DR event.     

New experimental initiatives using very highly charged ions from an “electron beam ion trap”

A short review of the experimental program in highly-charged heavy ion physics conducted at the Lawrence Livermore National Laboratory Electron Beam Ion Trap (EBIT) facility is presented. The heavy-ion research, involving ions up to fully stripped U⁹²⁺, includes precision x-ray spectroscopy and lifetime studies, electron impact ionization and excitation cross section measurements. The investigations of ion-surface interactions following the impact of high-Z highly charged ions on surfaces are aimed to study the neutralization dynamics effecting the ion and the response of the surface as well. The combination of an EBIT% with a cryogenic Penning Trap (“RETRSP”) allows to conduct experiments with ultra cold (e.g. 10 K) very highly charged ions. These studies of charge exchange processes, Coulomb crystals and measurements of hyperfine transitions using laser spectroscopy are in progress.     

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.     

Precision laser spectroscopy of highly charged ions

Recently, intense beams of highly charged ions have become available at heavy ion cooler rings. The obstacle for producing these highly interesting candidates is the large binding energy of K-shell electrons in heavy systems in excess of 100 keV. One way to remove these electrons is to strip them off by passing the ion through material. In the cooler ring, the ions are cooled to a well defined velocity. At the SIS/ESR complex it is possible to produce, store, and cool highly charged ions up to bare uranium with intensities exceeding 10⁸ atoms in the ring. This opens the door for precision laser spectroscopy of hydrogenlike-heavy ions, e.g.²⁰⁹Bi⁸²⁺, and allows to examine the interaction of the single electron with the large fields of the heavy nucleus, exceeding any artificially produced electric and magnetic fields by orders of magnitude. In the electron cooler the interaction of electrons and highly charged ions otherwise only present in the hottest plasmas can be studied.