ELETTRA Storage Ring Research Articles

Upgrade of the Superconducting Multipole Wiggler Magnetic System for the ELETTRA Storage Ring

The article describes the magnetic system modernization of the wiggler installed at the ELETTRA storage ring in 2002. This work was made in Budker Institute of Nuclear Physycs SB RAS in 2017. Modernization touched, mainly, changes in the parameters of superconducting coils.

An IAEA multi-technique X-ray spectrometry endstation at Elettra Sincrotrone Trieste: benchmarking results and interdisciplinary applications.

The International Atomic Energy Agency (IAEA) jointly with the Elettra Sincrotrone Trieste (EST) operates a multipurpose X-ray spectrometry endstation at the X-ray Fluorescence beamline (10.1L). The facility has been available to external users since the beginning of 2015 through the peer-review process of EST. Using this collaboration framework, the IAEA supports and promotes synchrotron-radiation-based research and training activities for various research groups from the IAEA Member States, especially those who have limited previous experience and resources to access a synchrotron radiation facility. This paper aims to provide a broad overview about various analytical capabilities, intrinsic features and performance figures of the IAEA X-ray spectrometry endstation through the measured results. The IAEA-EST endstation works with monochromatic X-rays in the energy range 3.7-14 keV for the Elettra storage ring operating at 2.0 or 2.4 GeV electron energy. It offers a combination of different advanced analytical probes, e.g. X-ray reflectivity, X-ray absorption fine-structure measurements, grazing-incidence X-ray fluorescence measurements, using different excitation and detection geometries, and thereby supports a comprehensive characterization for different kinds of nanostructured and bulk materials.

A survey of the Italian research in solid state physics by infrared spectroscopy with electron-beam sources

Two beamlines for the use of InfraRed Synchrotron Radiation (IRSR) are presently working in Italy, at the ELETTRA storage ring in Trieste, and at the collider DAFNE in Frascati. A third facility, SPARC in Frascati, has been equipped for the extraction of Terahertz radiation with the aim to perform pump-probe time-domain experiments. Here we describe those apparata and we review the main results that the Italian groups have obtained therein, in recent years, in solid-state physics. We also describe the experiments performed in collaboration with the storage ring BESSY in Berlin, for the exploitation of Coherent Synchrotron Radiation, and the terahertz beam line recently implemented at SPARC, the Free Electron Laser of Laboratori Nazionali di Frascati

Experimental demonstration of frequency pulling in single-pass free-electron lasers

Frequency pulling is a well-known phenomenon in standard laser physics, leading to a shift of the laser frequency when the cavity and maximum gain frequencies are detuned. In this letter we present the first experimental demonstration of frequency pulling in single-pass free-electron lasers. Measurements are performed using the single-pass free-electron laser installed on the Elettra storage ring.

Infrared studies under pressure at the infrared beamline SISSI at ELETTRA

Transition metal oxides often display insulator to metal transitions (MIT) with conductivity jumps up to several orders of magnitude, which makes them very attractive both for technological applications and for the several fundamental issues they raise. Information about the mechanism inducing the MIT may be gained by means of infrared (IR) spectroscopy. We present here the capabilities of the IR synchrotron source SISSI (Synchrotron Infrared Source for Spectroscopy and Imaging), at the Italian storage ring ELETTRA. We demonstrate SISSI to be a powerful source for optical studies of pressure-induced insulator-to-metal transitions, reporting on V3O5 and (V0.989Cr0.011)2O3 as examples.

Advanced photoelectric effect experiment beamline at Elettra: A surface science laboratory coupled with Synchrotron Radiation

We report the main characteristics of the advanced photoelectric effect experiments beamline, operational at Elettra storage ring, featuring a fully independent double branch scheme obtained by the use of chicane undulators and able to keep polarization control in both linear and circular mode. The paper describes the novel technical solutions adopted, namely, (a) the design of a quasiperiodic undulator resulting in optimized suppression of higher harmonics over a large photon energy range (10-100 eV), (b) the thermal stability of optics under high heat load via cryocoolers, and (c) the end station interconnected setup allowing full access to off-beam and on-beam facilities and, at the same time, the integration of users' specialized sample growth chambers or modules.

Sub-picosecond coherent VUV source on the Elettra storage ring

Taking advantage of the storage ring free electron laser beamline at Elettra, we have implemented an experimental setup for the generation of sub-picosecond (ps) coherent optical pulses in the VUV range. The setup is based on the frequency up-conversion of a high-power external signal (provided by a Ti:Sapphire laser) and makes use of a relativistic electron bunch as resonating medium. The produced VUV pulses have peak power in MW range, variable polarization, high shot to shot stability and control of the timing parameters at the ps level. In this paper, we present the first characterization of the temporal and spectral features of the emitted light. The radiation can be exploited for new experiments in the fields of dynamical phenomena, non-linear physics, magnetism and biology.

Experimental Characterization of Nonlinear Harmonic Generation in Planar and Helical Undulators

We present an experimental characterization of the process of coherent harmonic generation in single-pass free electron lasers. The harmonic radiation is obtained by seeding the electron beam stored in the Elettra storage ring with a Ti:sapphire laser. Different methods for generating harmonics are compared between them, and a detailed characterization of the emitted light is performed for different polarizations. Our results also contribute to the debate about the possible presence of a coherent on-axis signal in helical undulators. In this respect, we provide an experimental confirmation of recent theoretical studies that predict no coherent on-axis signal.

Performance of SISSI, the infrared beamline of the ELETTRA storage ring

The results of pilot experiments carried out at the new infrared beamline SISSI (Source for Imaging and Spectroscopic Studies in the Infrared) operated at the synchrotron laboratory ELETTRA in Trieste, Italy, are presented and compared with the results obtained with conventional IR sources. The main figures of merit of the infrared synchrotron radiation (IRSR) such as brightness, spectral quality, and stability are discussed. Using a pinhole scanned across the IRSR beam, the effective beam size, the intensity, and the lateral distribution for different wavelengths are determined. The results obtained on geological and biological samples are used to illustrate how the broadband nature and high brightness of the IRSR beam allow IR spectroscopy experiments on diffraction-limited sample areas in both the mid-IR and far-IR regions.

Soft X‐ray excitation of luminescence in wide bandgap crystals doped with rare‐earth ions

AbstractLuminescence excitation spectra of wide bandgap oxide crystals were measured in the soft X‐ray range of excitation (300–750 eV) at the BEAR beamline of the electron storage ring Elettra (Trieste). We give a special attention to changes of the light yield in the vicinity of the absorption K‐edge of oxygen. The excitation spectra of two well‐known scintillators YAG‐Yb and LuAP‐Ce (chemical formulae are Y3Al5O12:Yb (15%) and LuAlO5:Ce (0.4%)) reveal a non‐proportional change of the quantum yield and a different response to the jump of absorption coefficient at the 1sO edge for certain emission bands. The analysis of experimental data shows that both the surface loss and interaction effects between secondary electronic excitations (EEs) can influence the energy conversion process in crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Experimental studies on transient beam loading effects in the presence of a superconducting third harmonic cavity

In the framework of the SUPER-3HC project, an idle superconducting third harmonic cavity is installed in the ELETTRA storage ring in order to lengthen the bunch, thus improving the Touschek Lifetime. An improvement of more than a factor three of the beam lifetime is obtained, and the induced Landau damping renders ELETTRA longitudinally stable for the first time. The paper describes the performed studies and the experimental results, showing a strong correlation between the presence of an empty gap in the filling pattern of the ring and the third harmonic cavity induced Landau damping of the longitudinal instabilities, the bunch lengthening modulation along the bunch train and the beam lifetime improvement. Finally, an experimental investigation on the bunch profile overstretching, leading to find a low overstretching threshold below which the beam lifetime continues to increase, is presented.

Facility Updates: Fermi @ Elettra: A Free Electron Laser for EUV and Soft X-ray Radiation

Sincrotrone Trieste has received funding and has begun the final refinement of technical parameters as well as the construction of a new Free Electron Laser (FEL) called Fermi. The new light source will be located adjacent to the existing Elettra storage ring and will use the linac that presently injects electrons into this light source. The linac will shortly become fully available to the Fermi project as a new dedicated full energy injection system is also being built for Elettra. Why are VUV and X-ray FELs so important and how do they work? Most readers will know that in a bending magnet, synchrotron radiation is created by the incoherent emission of each electron as it moves in a magnetic field.

Software of the standalone control system for 49-pole superconducting wiggler

The paper describes the software of the standalone control system for 49-poles superconducting wiggler with magnetic field 3.5 T. This wiggler was fabricated in Budker INP for ELETTRA Storage Ring (Trieste, Italy). The description of instrumentation is brief. Unlike this, the software description is more detailed, as software basically determines functional capabilities of standalone system. Described software consists of two parts: embedded part operating in VME controller and high-level part operation on host machine. Embedded part is the main part of the software. It provides the interactions with the hardware and realizes all algorithms for MSCW control. Host software organizes user interface.

The synchrotron infrared beamline SISSI at ELETTRA

The infrared synchrotron radiation emitted from a bending magnet of the third generation storage ring ELETTRA is studied in detail by ray-tracing techniques. Constant magnetic-field and edge infrared emissions are taken into account in the project of the bending vacuum chamber and on the beamline design. Moreover the gain in flux and brightness with respect to a conventional source of the infrared radiation are calculated and discussed.

The infrared synchrotron radiation beamline at the third generation light source ELETTRA

The synchrotron radiation emitted in the infrared range from a bending magnet of the third generation storage ring ELETTRA is studied in detail by simulation techniques. Edge effects are taken into account. Preliminary experimental checks on an existing port for beam diagnostics are reported. The design of the infrared beamline under construction, including an evaluation of the tolerance on mirror parameters and of thermal distortions, is presented. Finally, the gain in flux and brightness with respect to a conventional source and the polarization degree of the infrared radiation are calculated and discussed.

Broad band impedance measurements on the electron storage ring ELETTRA

In the design of the vacuum chamber of a storage ring, special care has to be taken to keep the impedance as low as possible, in order to not degrade the quality of the circulating beam. Since the start of the commissioning of the Italian synchrotron light source ELETTRA in 1993, several low gap insertion vacuum chambers with internal aperture of 14 mm have been installed into the storage ring. Monitoring of their individual impedances and effects has been carried out with measurements on the electron beam after each new installation. The subsequent evolutions of the total longitudinal and transverse impedances are presented in this paper. Furthermore, in contradiction with the foreseen single-bunch effect, noticeable excitations of particular narrow band longitudinal coupled multibunch instabilities as a function of the position of the blades of the vertical scraper have been observed. In order to achieve a deeper insight of the phenomenon, an exhaustive characterization of both the longitudinal and transverse impedances of the scraper has been carried out.

Operation and performance of a free electron laser oscillator down to 190 nm

We present recent results obtained by the European Free Electron Laser (FEL) project at the ELETTRA storage ring. Coherent and tunable light was produced in the ultraviolet down to below 190 nm, the shortest lasing wavelength obtained so far with a FEL oscillator. The performance of the FEL is described, together with a series of technical solutions that have been adopted on it. These solutions increase its validity as a source for applications, and demonstrate the potential of FEL oscillators to become sources with features in the vacuum ultraviolet.

Double photoionization of He at 80 eV excess energy in the equal-energy-sharing condition

The high flux of the gas-phase beamline at the Elettra storage ring, Trieste (Italy), and the efficiency of a multicoincidence end station have been combined to measure the triple-differential cross section (TDCS) for the double photoionization (DPI) of He at excess energies $E=20$ and 80 eV. The TDCS has been measured in the equal-energy-sharing kinematics, in which the kinetic energies of the two photoelectrons are equal ${(E}_{1}{=E}_{2}=E/2).$ The experiments are compared with the predictions of a many-body Coulomb wave method and a convergent close-coupling calculation. The symmetrized gerade amplitudes of the He (DPI) extracted by the experiments as well as by the two calculations have been fitted by a Gaussian function. The results support the validity of the parametrization of the gerade amplitude via only one parameter, the full width at half maximum ${\ensuremath{\vartheta}}_{1/2},$ of the Gaussian function, up to 80 eV above threshold.

Complementary TDCS for thephoto-double ionization of He at 40 eV above the threshold inunequal energy-sharing conditions

Photo-double ionization (PDI) of helium at 40 eV above the threshold has been studied for unequal energy-sharing in thecomplementary kinematics obtained in two measurements by theinterchange of the kinetic energies E1↔E2 of the two photoelectrons. Thetriple differential cross sections (TDCS) were measured inthe plane perpendicular to the photon direction using the multicoincidence end-station of the gas-phase photoemissionbeam-line of the Elettra storage ring. The measured TDCSs werecompared with previous experimental results using a practicalparametrization proposed by Cvejanovic and Reddish (2000 J. Phys. B: At. Mol. Opt. Phys. 33 4691) and with predictions of the 3C and convergentclose-coupling calculations. Satisfactory agreement with theprevious experimental data was found. The comparison with thetwo theoretical models shows that the TDCSs is the complementarykinematics still present a challenge for PDI theory.

An advanced KB mirror pair for microfocusing

A new range of micro-focusing mirrors based on KB pairs has been developed by SESO for Beamline Nanospectroscopy at the Elettra Storage Ring in Trieste, Italy. Both the focusing and the aspheric shape are adjustable with stepper motors. The goal of the beamline is to have a high photon density spot with a variable size in the experimental chamber over the whole soft X-ray range. The estimated dimension of the final spot should be smaller than 4 μm 2 FWHM, with a photon density of the order of 10 13 photons/s μm 2; this may be achieved only by accepting an angular divergence on these mirrors of between 5 and 10 mrad. This condition can be fulfilled only with elliptical (or plane elliptical) mirrors with very limited residual slope errors (below 1 μrad RMS) that are able to correct even small focal distance errors.