This paper presents the design, implementation, and experimental methods of the Delhi Penning trap (DPT) setup for the background-free study of electron-impact ionisation in the relativistic regime. The setup combines trapped ions with the electron beam of a free-electron laser. It employs a cryogenic cylindrical Penning trap that is devoted to the study of charge breeding of highly charged ions by electron-impact ionisation in the regime of relativistic electron energies in the range from 1 to 8 MeV. In particular, the experiment focuses on the ionisation cross sections in this yet sparsely explored energy regime, and on subsequent spectroscopy of the produced highly charged ions.

We discuss the confinement of an electron in a Penning trap as the realisation of a one-dimensional quantum-mechanical oscillator. In such a situation, the non-zero ground-state energy of the electron in the confining electric and magnetic fields of the trap (as compared to the classical zero of the energy of a free electron) plays a role in certain kinds of investigations, and can be directly measured with high precision in photo-detachment spectroscopy of confined atomic anions such as H − . We detail a concrete implementation of such a measurement and discuss its implications.

We have performed systematic measurements of the resistive cooling behavior of bunches of highly charged ions in a Penning trap after injection from an external source. In particular, we have been able to measure the exponential cooling rate of the axial center -of -mass motion and experimentally show its linear dependence on the ion number within the bunch, as expected from theory. The common center -of -mass energy of the ions is reduced by more than four orders of magnitude on the time scale of milliseconds while the single -ion cooling occurs on the scale of seconds, representing a highly effective way to remove the dominating part of the ion kinetic energy.

Microwave spectroscopy of confined particles in Penning traps is mainly applied to magnetic dipole transitions in various contexts. The strong magnetic field of the Penning trap gives rise to significant spin orientation energies and to Zeeman splitting of lines, which can be used for precision spectroscopy of magnetic dipole transitions and the determination of magnetic moments. Prominent examples are the precision measurements of the magnetic moments (g-factors) of the free (unbound) electron, proton and their anti-particles, as well as of the bound electron by Larmor frequency measurements, and in general the application to the Zeeman splitting of levels that occurs due to the presence of magnetic field used for confinement. We will discuss these applications in detail below.

Deviations from the idealised situation described in Chap. 6 as they are present in real Penning traps give rise to a number of effects. Some of these can be minimized by efforts to approach the ideal situation as closely as possible. Others are inherent to the situation and cannot be avoided or circumvented, and we will discuss them below. In particular in precision measurements, a number of imperfections may be of relevance. The most prominent imperfections in experimental setups are non-ideal electric and magnetic fields, misalignments of the trap axis with respect to the axis of the magnetic field and mechanical imperfections of trap electrodes. Such imperfections can in principle be avoided by appropriate choice of experimental parameters, in reality however, they are present and need to be taken into account in the analysis of the data. Let us have a look at the effects and their magnitudes.

We present a non-destructive electronic detector for stored charged particles in a Penning trap that uses a symmetric electrode arrangement for signal pickup and a resonator without tap. This system has advantageous off-resonance features which are demonstrated by means of detection and cooling measurements with highly charged ions in a cryogenic Penning trap. In particular, it allows for particle detection across a wide range of frequencies that is not concomitant with cooling and offers a novel way to tune a trap with the help of non-destructive measurements on large particle ensembles.

This chapter takes a look at the effects and possible implementations of specific magnetic field geometries, mainly of so-called 'magnetic bottles' which are a key ingredient to the application of the continuous Stern-Gerlach effect in Penning traps.

We present a systematic and quantitative investigation of the electrostatic anharmonicity in cylindrical Penning traps that is induced by the presence of radial holes for access to the trap center. The expected distortion of the electrostatic potential is studied as a function of the relative hole size, shape, arrangement, and number.

The oldest Penning trap geometry in use is the hyperbolic shape, which provides good confinement properties by design, however was difficult to machine to high precisions at the time of its introduction, and offers limited access for particles and laser beams. Thus, cylindrical designs were brought forward, including more open structures with open endcaps. Here, we briefly review the hyperbolic and the most important forms of cylindrical Penning traps.

This second edition is an updated and extended introduction to the world of Penning traps and provides an overview of the field.

We have developed and operated an electronic system for the non-destructive detection and cooling of charged-particle bunches that are captured and confined in a Penning trap, together with methods for the evaluation of corresponding measurements that allow for a detailed characterization of each individual particle bunch. Once calibrated, from a single measurement of the particles’ induced electronic signal as a function of time directly upon capture, the setup and method allow for a fast determination of the initial and final absolute particle energies, of the cooling rate, and of the absolute number of particles in the bunch. We demonstrate this with highly charged ions (Ne8+) that are injected into the Penning trap of the HILITE experiment.

We have developed and operated an electronic detection system for the non-destructive single-pass detection of bunches of charged particles in a beamline that allows for a measurement of their lateral position with respect to the central beamline axis on a shot-to-shot basis. It provides all features of our related development reported in Kiffer et al. (Rev Sci Instrum 90:113301, 2019), namely single-pass measurement of bunch length, kinetic energy and absolute charge, and is additionally designed to provide the lateral position of bunches with sub-mm accuracy. We show the setup, associated methods and provide characterizing measurements with bunches of highly charged ions in the keV regime of kinetic energy that demonstrate the capabilities and show a typical application.

"String theory and the real world: the visible sector, 2nd edition." Contemporary Physics, ahead-of-print(ahead-of-print), p. 1

"Synchrotron radiation: sources and applications to the structural and electronic properties of materials." Contemporary Physics, ahead-of-print(ahead-of-print), p. 1

"Relativity and cosmology: volume 5 of modern classical physics." Contemporary Physics, 62(2), p. 122

The discovery and in part also the further study of exoplanets have gained quite a lot of media attention in the last decade or so. The idea that stars other than our Sun may have planets as well, and that these ‘exoplanets’ may be Earth-like and located in the so-called ‘habitable zone’, possibly capable of supporting life, is centuries old. But proof and scientific study have been provided only fairly recently, with the vast majority of scientific results from the NASA Kepler mission, a space probe in an orbit around the Sun, much similar to Earth’s orbit. Named after German astronomer Johannes Kepler, it consists mainly of a large space telescope that has been in operation from 2009 to 2018. During that time, it has observed around half amillion stars and found some 2500 exoplanets, some of which have been shown to be Earth-like and in the habitable zones of their stars. Kepler,mainly being a large photometer, has used the slight periodic variation of the amount of light detected from a star (dimming) when a planet passes in front of it to study that planet. The present book The NASA Kepler Mission sets out to give a general account of this undertaking, from a discussion of the mission and its background to the technology of the probe and the methods of study, and to the variety of scientific results. It is part of the ‘AAS IOP Astronomy’ book series where the American Astronomical Society (AAS) have partnered with IOP Publishing ‘to create an exciting new collection of astronomy and astrophysics books to further the AAS mission to enhance and share humanity’s scientific understanding of the universe.’ The title of the book may as well be The NASA Kepler and K2 Missions (which actually is the title of the first chapter after the introduction), since the original Kepler mission encountered technical problems after about four years of operation, and had to be changed in order to make use of the instrument in spite of those problems, hence creating the so-called ‘K2’ mission, which is also covered in the current text. It consists of a thorough discussion of the mission (‘The NASAKepler and K2Missions’) and an account of the most prominent subjects of study (‘Exoplanets’) followed by the additional fields of study ‘Stellar Astrophysics with Kepler and K2’, ‘The Solar System as Observed by K2’ and ‘Extragalactic Studies from the Kepler/K2 Missions’. The text has been edited by Steve B. Howell from the NASA Ames Research Center, a central figure of the mission, and contains contributions by some twenty authors who were all involved in the various aspects of the mission. The text is nicely written in a somewhat personal style, easily accessible yet precise and fully referenced to scientific publications. It is supported by ample colour plots and pictures taken of and by the Kepler telescope. Rather than having each author contribute one chapter to the book, the individual contributions are short and nicely integrated into the main text by use of text boxes, which increases the readability. It is overall very accessible, also owing to the fact that no mathematics or formal scientific training is necessarily required to understand most of the material presented. The book itself is a hardback (ISBN 9780750322942) and well made regarding the paper, the print and the binding. It is also available as an e-book, in a ‘mobi’ version for mobile reading devices, and offers a ‘myprint’ option for those whose institutions have already bought the book electronically, thus making a print copy available at a price of typicallyUSD30. It can be recommended to anyone with a general interest in the engineering and science of space telescopes, or more specifically with the study of exoplanets by space-based photometry. It provides an interesting and informative read about the Kepler mission for interested laypersons to experts.

"Electrons in motion: attosecond physics explores fastest dynamics." Contemporary Physics, 62(2), p. 119

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