Ultra-Low-Emittance Light Sources

In this special issue, we delve into the subject of ultra-low-emittance storage ring light sources. While these go under various names, such as “diffraction-limited storage rings” and “ultimate storage rings,” perhaps the most universally applicable name is “fourth-generation storage rings” or 4GSRs. As this name suggests, these rings promise improvements in X-ray brightness that are comparable to those seen in the transition from second- to third-generation rings.     

Theory of crystalline beams

Coulomb crystals in storage rings have been studied theoretically but not observed experimentally. We review here some aspects of the theory of crystalline beams and show that the main requirement to achieve crystallization is not fulfilled by existing storage rings. This revised version was published online in July 2006 with corrections to the Cover Date.     

电子储存环直线节中的轫致辐射的剂量率的计算

电子储存环的电子束流与环中的残余气体碰撞会产生轫致辐射,这也是造成储存环中束流损失的主要原因之一.一直以来,由于各种原因,人们在辐射防护上并没有给予它足够的重视.本文通过一些经验公式对该轫致辐射进行了分析和计算:(1)该轫致辐射会导致较高的剂量率,尤其是在直线节;(2)影响剂量率的几个主要因素;(3)轫致辐射中的高能粒子占有很大的比例.     

Superconducting Wigglers

In low- and medium-energy storage rings for synchrotron radiation (SR) production, it is necessary to use high-performance insertion devices (IDs) in order to meet the increasing demand for high X-ray flux to perform life science and material science, since the maximum beam energy and beam current cannot be changed in storage rings without major rebuilds of the accelerator systems.     

The potential for neutrino physics at muon colliders and dedicated high current muon storage rings

Conceptual design studies are underway for muon colliders and other high-current muon storage rings that have the potential to become the first true “neutrino factories”. Muon decays in long straight sections of the storage rings would produce precisely characterized beams of electron and muon type neutrinos of unprecedented intensity. This article reviews the prospects for these facilities to greatly extend our capabilities for neutrino experiments, largely emphasizing the physics of neutrino interactions.     

Storage ring: An advanced tool in modern research

These introductory notes give a personal flavoured view on the developments, opportunities and perspectives of ion storage rings with cooling devices including some highlights of applications in various fields of research. First some historical remarks are made on the development of cooler rings and cooling techniques, highlighted by the observation of “orderliness” in cooled heavy ion beams. In the main part recent experimental highlights from storage rings in the fields of particle-, nuclear and atomic physics are reviewed. The lecture will end with a look at future projects and a dream. This revised version was published online in July 2006 with corrections to the Cover Date.     

Meeting Reports: Energy-Recovering Linacs for Next-Generation Light Sources

Energy-recovering linear accelerators (ERLs) have the potential of providing two orders of magnitude increase in brightness over third-generation sources while offering bunch lengths as low as tens of femtoseconds for timing experiments. ERLs are different from storage rings in that the electron bunches circulate once only. Thus they are not at equilibrium, and in particular can be packed much more tightly than in storage rings, resulting in brighter sources. However, dumping a 100 mA, 3 GeV beam that carries 300 MW of energy is not practical, so the energy is recovered, and the devices are in some sense energystorage rings.     

A Code for Bunch Lengthening Simulation

Bunch lengthening phenomenon is resulted from one of the most severe single bunch instabilities in storage rings. We develop a new code to calculate the single bunch length and energy spread in storage rings using FORTRAN. In this code, wake field is calculated using an analytical formula, which is different from the previous ones. The bunch length and energy spread under different bunch currents are calculated for BEPCII by using this code, and the tracking results are in good agreement with those from other codes. The calculated energy spread clearly shows that the longitudinal microwave instability threshold is around 65 mA for BEPCII storage ring.     

Free electron lasers in storage rings

In this paper we briefly describe the principle of the free electron laser in a storage ring and the results obtained recently at Orsay. We also discuss the expected performances of such a device in more modern storage rings.     

Beam extraction with electron pick-up

It is shown that electron pick-up from a cooling electron beam can be used to extract an ion beam from a storage ring. The technique is described and extraction times are estimated. A few applications for medium-energy ion storage rings are given.     

Trapping and focusing ground state atoms with static fields

Possibilities of trapping ground state atoms in static fields are studied. It is shown that it is impossible to trap ground state particles at rest using arbitrary combinations of electric, magnetic, and gravitational fields, a result which is a considerable generalization of Wing's theorem. Similarly, it is impossible to make a thin lens for ground state atoms using static fields. Confinement of ground state particles in dynamic equilibrium can be achieved. Axially symmetric storage rings with electric or magnetic fields are possible and should be experimentally feasible. Such storage rings have the important advantage that ground state particles can be confined, hence loss of atoms by two-body collisions is avoided.     

Generation of ultrashort coherent vacuum ultraviolet pulses using electron storage rings: a new bright light source for experiments

We demonstrate for the first time that seeded harmonic generation on electron storage rings can produce coherent optical pulses in the vacuum ultraviolet spectral range. The experiment is performed at Elettra, where coherent pulses are generated at 132 nm, with a duration of about 100 fs. The light source has a repetition rate of 1 kHz and adjustable polarization; it is very bright, with a peak power several orders of magnitude above that of spontaneous synchrotron radiation. Owing to high stability, the source is used in a test photoemission electron microscopy experiment. We anticipate that seeded harmonic generation on storage rings can lead to unprecedented developments in time-resolved femtosecond spectroscopy and microscopy.     

Renormalized Fokker-Planck equation for the problem of the beam-beam interaction in electron storage rings

It is shown that the beam-beam interaction in electron storage rings is equivalent to an additional source of noise for the particle betatron oscillations. A weak white noise acting upon a nonlinear oscillator causes a fast loss of coherence in its phase. This loss of coherence induces a broadening of the resonances, thus avoiding the problem of the divergent perturbative series which arises in the study of nonintegrable Hamiltonian systems. A “renormalized” Fokker-Planck equation is established which contains new diffusive terms corresponding to the presence of resonances. The solution of this equation is exhibited explicitly in a simplified case. This allows an analytical approach to the problem of the beam-beam instability, which sets an upper limit to the maximum attainable luminosity in storage rings.     

Compact IR synchrotron beamline design

Third‐generation storage rings are massively evolving due to the very compact nature of the multi‐bend achromat (MBA) lattice which allows amazing decreases of the horizontal electron beam emittance, but leaves very little place for infrared (IR) extraction mirrors to be placed, thus prohibiting traditional IR beamlines. In order to circumvent this apparent restriction, an optimized optical layout directly integrated inside a SOLEIL synchrotron dipole chamber that delivers intense and almost aberration‐free beams in the near‐ to mid‐IR domain (1–30 µm) is proposed and analyzed, and which can be integrated into space‐restricted MBA rings. Since the optics and chamber are interdependent, the feasibility of this approach depends on a large part on the technical ability to assemble mechanically the optics inside the dipole chamber and control their resulting stability and thermo‐mechanical deformation. Acquiring this expertise should allow dipole chambers to provide almost aberration‐free IR synchrotron sources on current and `ultimate' MBA storage rings.     

RI Beam Factory project at RIKEN

The RI Beam Factory is being proposed at RIKEN, which is a project to construct two superconducting ring cyclotrons (SRC-4 and SRC-6), experimental storage rings (MUSES) and experimental facilities. Heavy ions are to be accelerated to energies of up to 400 AMeV for light nuclei and 150 AMeV for the heaviest nuclei by the SRC-6 and up to 1400 AMeV in the MUSES. Wide varieties of radioactive nuclear beams are to be supplied as secondary beams. Electrons, stable nuclei, and highly charged ions in addition to radioactive nuclei can be stored in the storage rings. The MUSES provides various collision methods, such as colliding, merging, and internal target modes. A few of the selected new nuclear-physics opportunities are discussed briefly.     

How it All Started at DESY in 1964

To put it bluntly, synchrotrons and storage rings were originally not intended to become light sources for synchrotron radiation (SR). If particle physicists had not driven this development for their own needs, we would not yet have these sources available at their present level of sophistication. In 1964, when the then-6 GeV synchrotron DESY at the newly founded Hamburg institution of the same name started operating, SR was considered at best a nuisance. Accelerating an electron to 6 GeV was accompanied by a loss of 9.35 GeV on its way due to this radiation, and later, at 7.5 GeV, the loss amounted to 22.8 GeV. How could it then happen that today all of the DESY storage rings and linear accelerators are devoted to SR?     

Polarized beams at storage rings

This paper reviews modern techniques to accelerate polarized particles to high energy and to preserve their polarization in the storage rings. Possibilities of the bean polarization control are discussed for proton and electron machines.     

Birefringence induced by pp-wave modes in an electromagnetically active dynamic aether

The European Physical Journal C - We calculate the corrections for constant radial magnetic field in muon $${g}-2$$ and electric-dipole-moment experiments in storage rings. While the correction is...     

Applications of X-ray absorption spectroscopy in materials science: Status and new trends

X-ray absorption spectroscopy (XAS) is a local probe of the geometric and electronic structure of individual atomic species in condensed matter. With the availability of intense, polarized and highly collimated X-rays from storage rings the technique has found a widespread application in physics, chemistry, biology and geology. Multiple scattering of the photoelectron in the edge region and in shadowing configurations makes it possible to deduce higher correlations in the atomic arrangement besides the pair correlation obtained from standard EXAFS. This gives radial and angular information on the geometric structure. A promising new application is XAS under total external reflection with detection of the absorption by fluorescence. This allows in-situ investigations of solid-solid, solid-liquid and solid-gas interfaces. New dedicated storage rings with high brilliance will have a major impact on XAS in dispersive mode and for very dilute systems.     

One way only to synchrotron light sources upgrade?

The last decade has seen a renaissance of machine‐physics studies and technological advancements that aim to upgrade at least 15 synchrotron light sources worldwide to diffraction‐limited storage rings. This is expected to improve the average spectral brightness and transversally coherent fraction of photons by several orders of magnitude in the soft‐ and hard‐X‐ray wavelength range, at the expense of pulse durations longer than ～80 ps FWHM. This paper discusses the compatibility of schemes for the generation of sub‐picosecond photon‐pulse durations in synchrotron light sources with standard multi‐bunch user operation and, in particular, diffraction‐limited electron optics design. The question of this compatibility is answered taking into consideration the storage ring beam energy and the constraint of existing synchrotrons' infrastructure. An alternative scheme for the upgrade of medium‐energy synchrotron light sources to diffraction‐limited storage rings and the simultaneous production of picosecond‐long photon pulses in a high‐gain free‐electron laser scheme are illustrated.