Beta decay of highly charged ions has attracted much attention in recent years. An obvious motivation for this research is that stellar nucleosynthesis proceeds at high temperatures where the involved atoms are highly ionized. Another important reason is addressing decays of well-defined quantum-mechanical systems, such as one-electron ions where all interactions with other electrons are excluded. The largest modifications of nuclear half-lives with respect to neutral atoms have been observed in beta decay of highly charged ions. These studies can be performed solely at ion storage rings and ion traps, because there high atomic charge states can be preserved for extended periods of time (up to several hours). Currently, all experimental results available in this field originate from experiments at the heavy-ion complex GSI in Darmstadt. There, the fragment separator facility FRS allows the production and separation of exotic, highly charged nuclides, which can then be stored and investigated in the storage ring facility ESR. In this review, we present and discuss in particular two-body beta decays, namely bound-state beta decay and orbital electron capture. Although we focus on experiments conducted at GSI, we will also attempt to provide general requirements common to any other experiment in this context. Finally, we address challenging but not yet performed experiments and we give prospects for the new radioactive beam facilities, such as FAIR in Darmstadt, IMP in Lanzhou and RIKEN in Wako.

Beta decay of highly charged ions

Beam Intensity Measurements.- Thermal Aspects.- Beam Profile Measurements.- Measurements with Capacitive or Inductive Pickups.- Measurements in Phase Spaces.- The Longitudinal Phase Plane.- The Electromagnetic Fields of Bunches.- Beam Loss Monitoring.- Some Interesting Specialized Aspects of Beam Diagnostics.

Beam instrumentation and diagnostics

A resonant pick-up for the detection of heavy ion Schottky noise was built into the ESR storage ring at GSI. A similar device will be installed at the cooler storage ring CSRe at IMP. Its purpose is a significant enhancement of the signal to noise ratio of Schottky spectra. A particular application of the new system is the measurement of circulating single ions. The resonator is based on a pillbox design. It is operated at air pressure, and is electromagnetically coupled to the vacuum tube of the storage ring via a cylinder-shaped ceramic gap. The resonant frequency can be changed by inserting plunger pistons. The resonator can easily be decoupled from the storage ring, if high beam impedances become a problem. The article describes the construction, electromagnetic properties of the pick-up as well as first experiments with heavy ion beams.

A fast and sensitive resonant Schottky pick-up for heavy ion storage rings

The theory and performance of electrodes used as kickers and pickups for charged‐particle beams are reviewed Specific devices such as striplines and travelling‐wave devices are discussed (AIP)

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Dynamic Devices A Primer on Pickups and Kickers

https://link.aps.org/pdf/10.1103/PhysRevAccelBeams.23.054701

Towards storage rings as quantum computers

A conceptual survey and exposition is presented of some fundamendal aspects of fluctuations and coherence, as well as the interplay between the two, in coasting charged‐particle beams—both continuous and bunched—in storage rings. A detailed study is given of the spectral properties of the incoherent phase‐space Schottky fluctuations, their propagation as waves in the beam, and the analytic complex coherent beam electromagnetic response or transfer function. The modification or distortion of these by collective interactions is examined in terms of simple regeneration mechanisms. Collective or coherent forces in the beam–storage‐ring system are described by defining suitable impedance functions or propagators, and a brief discussion of the coherent collective modes and their stability is provided, including a general and rigorous description of the Nyquist stability criterion. The nature of the critical fluctuations near an instability threshold is explored. The concept of Landau damping and its connection with phase‐mixing within the beam is outlined. The important connection between the incoherent fluctuations and the beam response, namely the Fluctuation–Dissipation relation, is revealed. A brief discussion is given of the information degrees of freedom, and effective temperature of the fluctuation signals. Appendices provide a short resume of some general aspects of various interactions in a charged‐particle between‐environment system in a storage ring and a general introduction to kinetic theory as applied to particle beams.

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Swapan Chattopadhyay

Papers

Some fundamental aspects of fluctuations and coherence in charged-particle beams in storage rings