7Th international users meeting at elettra

The third annual meeting of ANKA Users took place on September 23 to 24, 2004, at the University of Karlsruhe in Germany. The venue was chosen specifically to stimulate and strengthen the scientific ties between the university and the ANKA light source, which is located at the Karlsruhe Research Centre about ten miles from the university campus. A further impetus for this year's venue was the appointment of Tilo Baumbach in 2004 both as head of the ANKA facility and concurrently as professor in the Faculty of Physics at the university, where he heads the Laboratory for the Application of Synchrotron Radiation.     

Fourth ANKA and KNMF User Meeting 2012

On October 10–11, 2012, the ANKA synchrotron radiation facility and the Karlsruhe NanoMicro Facility (KNMF), both user research facilities at the Karlsruhe Institute of Technology (KIT) in Germany, hosted their fourth joint annual user meeting at the Ettlingen Castle. In the extraordinary ambiance of the baroque palace, the ANKA and KNMF directorates (represented by Clemens Heske and Jürgen Mohr, respectively) welcomed almost 200 participants representing universities, research facilities, and companies from 10 different countries. The meeting was kicked off by KIT Chief Science Officer Volker Saile, who emphasized the positive developments and increase in user numbers at both facilities.     

A portable ultrahigh‐vacuum system for advanced synchrotron radiation studies of thin films and nanostructures: EuSi2 nano‐islands

A portable ultrahigh‐vacuum system optimized for in situ variable‐temperature X‐ray scattering and spectroscopy experiments at synchrotron radiation beamlines was constructed and brought into operation at the synchrotron radiation facility ANKA of the Karlsruhe Institute of Technology, Germany. Here the main features of the new instrument are described and its capabilities demonstrated. The surface morphology, structure and stoichiometry of EuSi₂ nano‐islands are determined by in situ grazing‐incidence small‐angle X‐ray scattering and X‐ray absorption spectroscopy. A size reduction of about a factor of two of the nano‐islands due to silicide decomposition and Eu desorption is observed after sample annealing at 1270 K for 30 min.     

A review of optical measurements at the aerosol and cloud chamber AIDA

This paper provides a survey of recent studies on the optical properties of aerosol and cloud particles that have been conducted at the AIDA facility of Forschungszentrum Karlsruhe (Aerosol Interactions and Dynamics in the Atmosphere). Reflecting the broad accessible temperature range of the AIDA chamber which extends from ambient temperature down to 183 K, the investigations feature a broad diversity of research topics, such as the wavelength-dependence of the specific absorption cross sections of soot and mineral dust aerosols at room temperature, depolarization and infrared extinction measurements of ice crystal clouds generated at temperatures below 235 K, and the optical properties of polar stratospheric cloud constituents whose formation was studied in chamber experiments at temperatures well below 200 K. After reviewing the AIDA research activity of the past decade and introducing the optical instrumentation of the AIDA facility, this paper presents illustrative examples of ongoing and already published work on optical measurements of soot aerosols, mineral dust particles, and ice crystal clouds.     

Catalysis Workshop at ANKA

“Shining Synchrotron Light on Catalysts at Work – Opportunities and Limitations” was the title of the workshop that took place on October 8, 2010, in Karlsruhe (Germany) as part of the ANKA/KNMF user meeting. More than 80 German and international guests met at this event. Tilo Baumbach (director of ANKA, Karlsruhe) outlined in his warm welcome speech that ANKA is more than only an open facility to future catalysis research — it really wants to act as “catalyst” for studying the structure of catalysts and properties in catalytic reactors. Jan-Dierk Grunwaldt, as one of the three organizers of this workshop, also welcomed the workshop participants from academia and industry and outlined the importance of studying catalysts under reaction conditions: More than 95% of all chemical products have “seen” a catalyst in course of their production. New catalysts are required in energy conversion, as well as more efficient and new catalysts in fine chemistry and environmental technology. Since the catalytic structure is mostly correlated to the structure on the atomic level, information about it is of profound importance. This was already demonstrated by Thorsten Ressler in his talk “Catalysis and Synchrotron Radiation” on the main ANKA/KMNF user meeting the day before. ANKA, with its mid-hard X-ray, soft X-ray, and infrared beamlines and embedded in the scientific environment of the KIT, is an excellent place for catalysis research as Stefan Mangold (ANKA) demonstrated in his short overview, and it is developing more and more toward this direction.     

Electron scattering for exotic nuclei

A brand-new electron scattering facility, the SCRIT Electron Scattering Facility, will soon start its operation at RIKEN RI Beam Factory, Japan. This is the world’s first electron scattering facility dedicated to the structure studies of short-lived nuclei. The goal of this facility is to determine the charge density distributions of short-lived exotic nuclei by elastic electron scattering. The first collision between electrons and exotic nuclei will be observed in the year 2014.     

XAFS16 at KIT: Five Days of Cutting-Edge X-ray Science in Karlsruhe

The sixteenth international conference on X-ray Absorption Fine Structure, XAFS16, was held August 23–28, 2015, at the Karlsruhe Institute of Technology (KIT) in Germany. Since the first such meeting in 1981, the XAFS conference series has become the foremost international meeting covering developments and applications in X-ray absorption spectroscopy. Jointly organized by KIT, DESY (Hamburg), HZB (Berlin), and the European XFEL (Hamburg), under the auspices of the International X-ray Absorption Society (IXAS), the XAFS16 conference hosted over 550 participants (including more than 160 young scientists) from 37 different countries, establishing a new record for the number of participants. The local organization was provided by the KIT institutes INE, IKFT, and ITCP and the ANKA synchrotron facility, with Jan-Dierk Grunwaldt leading the local organizing committee.     

Experiments on the physics of charged particle beams at the VEPP-4M electron-positron collider

The VEPP-4M accelerator facility with a universal KEDR detector is designed to conduct experiments with colliding electron-positron beams. High-energy physics, nuclear physics, and studies using synchrotron radiation are the main directions of research with this facility. In addition, experiments on poorly explored issues in the physics of beams in the electron-positron storage ring and methodological studies to prepare an experiment aimed at testing corollaries of the CPT theorem for an electron and a positron are regularly conducted at the VEPP-4 facility. A number of works performed in recent years are described: studies to increase the accuracy of comparing the electron and positron spin precession frequencies by the resonant depolarization method; measurements of the count rate of Touschek electrons as a function of the beam energy in a wide range; comparison of the methods for measuring the beam energy spread; a study of the electron beam dynamics when a nonlinear betatron resonance is crossed.     

Low emittance lattice for the storage ring of the Turkish Light Source Facility TURKAY

The TAC(Turkish Accelerator Center) project aims to build an accelerator center in Turkey. The first stage of the project is to construct an Infra-Red Free Electron Laser(IR-FEL) facility. The second stage is to build a synchrotron radiation facility named TURKAY, which is a third generation synchrotron radiation light source that aims to achieve a high brilliance photon beam from a low emittance electron beam at 3 Ge V. The electron beam parameters are highly dependent on the magnetic lattice of the storage ring. In this paper a low emittance storage ring for TURKAY is proposed and the beam dynamic properties of the magnetic lattice are investigated.     

LEPTA project: Formation and injection of positron beam

The project of the Low-Energy Particle Toroidal Accumulator (LEPTA) has been developed and is put into operation at the Joint Institute for Nuclear Research (Dubna). The LEPTA facility is a small positron storage ring equipped with an electron cooling system. The project positron energy is 2?C4 keV. The main purpose of the facility is to generate an intense flux of positronium atoms (the bound state of the electron and positron). The LEPTA storage ring was commissioned in September 2004. The positron injector was designed in 2005?C2010, and the beam transport channel was constructed in 2011. The experiments on electron and positron injection from the injector into the accumulator were started in August 2011. The results are reported here.     

The ALTO project at IPN-Orsay

The availability of both a tandem deuteron beam and a linac electron beam, the latter converted into Bremsstrahlung, at the new ALTO facility at IPN-Orsay offers a unique opportunity to compare the performance of a laser ion guide under different regimes. The ALTO accelerator has delivered its first electron beam at the end of 2005 and a design for a gas-cell prototype is being studied.     

The Windowless Gaseous Tritium Source of KATRIN

The objective of KATRIN is the determination of the mass of the electron anti-neutrino with a sensitivity of 200 meV by investigating the kinematics of the electrons from tritium β decay. It is currently under construction at KIT (Karlsruhe Institute of Technology).A key component of the KATRIN experiment is the Windowless Gaseous Tritium Source (WGTS), in which molecular tritium decays with an activity of 10¹¹ Bq. A precise understanding of the properties of the WGTS is mandatory for the neutrino mass determination. In particular the gas dynamics is crucial since the measured energy spectrum is influenced by inelastic scattering of the decay electrons with the tritium molecules as well as Doppler broadening of the electron energy. Therefore parameters of the WGTS such as purity, temperature, density and velocity distributions of the tritium gas and the magnetic field strength inside the WGTS have to be modeled in detail.This talk gives an overview of the simulation and modeling program package currently in development which allows us to study the influence of the WGTS parameters on the measured electron energy spectrum.     

飞秒电子束装置的初步实验结果

 上海应用物理研究所建造并调试了一台飞秒电子束装置。这台装置主要由一把S波段热阴极微波电子枪、一台alpha磁铁和一根SLAC型加速管组成。这台装置可以产生能量为 20~30 MeV,峰值电流为100 A,微束团长度为250 fs的电子束。这篇文章报道了这台装置的调试和电子束团参数的测量。     

A new approach for a multistage depressed collector for gyrotrons

A feasibility study for a two-stage depressed gyrotron collector has been performed. A new approach for an adiabatic magnetic decompression of the hollow electron beam has been used. It permits control of the radius of the constant magnetic flux surface, which determines the radial extension of the electron beam. Independent of the value of the magnetic field around the beam. For this purpose, either solenoidal coils or a ferromagnetic insert can be placed inside the hollow electron beam. Thus, the radial dimensions of a multistage depressed collector of a high-power high-frequency gyrotron can be kept within limits given by technological constraints. The energy sorting of the electron beam is improved by using electrodes inside the hollow electron beam for controlling the potential distribution. The additional control electrodes make it possible to eliminate almost all of the effect of secondary electrons on the operation of the collector. In order to demonstrate the proposed approach, a compact two-stage depressed collector has been designed for a 1.5-MW coaxial cavity gyrotron operating at 165 GHz in the transverse electric (TE)_31,17 mode, which is under development at FZK, Karlsruhe, Germany. Including the effect due to secondary electrons, a collector efficiency of 73% has been calculated with an average and peak heat dissipation density of about 240 W/cm² and 500 W/cm², respectively. This results in an increase of the output gyrotron efficiency from 36.5% to 62.6% when internal radio frequency (RF)-losses inside the gyrotron tube of 15% are taken into account     

POLAREX Study of polarized exotic nuclei at millikelvin temperatures

POLAREX (POLARization of EXotic nuclei) is a new facility for the study of nuclear magnetic moments and decay modes of exotic nuclei using the established On-Line Nuclear Orientation (OLNO) method. A radioactive beam of interest is implanted into a ferromagnetic host foil held at a temperature of order 10mK in a ³He - ⁴He dilution refrigerator. The foil is magnetized by an applied magnetic field and the nuclear spins become polarized through the internal hyperfine field. The angular distribution of decay products from the polarized sample is measured. Accurate values of nuclear moment are obtained by NMR. The new facility will have access to neutron-rich nuclides produced at the ALTO facility (Linear Accelerator at Orsay Tandem) by fission induced by electrons from the linear electron accelerator. Basic concepts and initial tests are outlined.     

The status of KATRIN

KATRIN will have the capability to push the limit on the mass of the electron anti-neutrino to 200 meV (90% C.L.) by investigating the kinematics of the electrons from tritium β decay very close to the endpoint of the β spectrum. The importance of this experiment will be discussed in various contributions to this school. KATRIN is currently under construction at KIT (Karlsruhe Institute of Technology). This talk gives an overview over the status of KATRIN with emphasis on the aspects of KATRIN not covered by the talks following this one.     

Generalized Clifford algebras: Orthogonal and symplectic cases

The concept of the Clifford algebra of a bilinear form defined on a vector space, is generalized to include both orthogonal and symplectic forms. This new characterization is intimately tied to a particular anti-automorphism defined on the algebras which in the orthogonal case, provides a unified approach to the reversion and principle anti-involutions of an ordinary Clifford algebra. Most attention is concentrated on the physically important symplectic Clifford algebras, including the link between these and Lie superalgebras.Until February, 1982 at the Institüt für Theoretische Physik, Universität Karlsruhe, 75 Karlsruhe 1, Kaiserstr. 12, W. Germany.     

Ionospheric modification at twice the electron cyclotron frequency

In 2004, a new transmission band was added to the HAARP high-frequency ionospheric modification facility that encompasses the second electron cyclotron harmonic at altitudes between approximately 220 and 330 km. Initial observations indicate that greatly enhanced airglow occurs whenever the transmission frequency approximately matches the second electron cyclotron harmonic at the height of the upper hybrid resonance. This is the reverse of what happens at higher electron cyclotron harmonics. The measured optical emissions confirm the presence of accelerated electrons in the plasma.     

Commissioning of a multi‐beamline femtoslicing facility at SOLEIL

The investigation of ultrafast dynamics, taking place on the few to sub‐picosecond time scale, is today a very active research area pursued in a variety of scientific domains. With the recent advent of X‐ray free‐electron lasers (XFELs), providing very intense X‐ray pulses of duration as short as a few femtoseconds, this research field has gained further momentum. As a consequence, the demand for access strongly exceeds the capacity of the very few XFEL facilities existing worldwide. This situation motivates the development of alternative sub‐picosecond pulsed X‐ray sources among which femtoslicing facilities at synchrotron radiation storage rings are standing out due to their tunability over an extended photon energy range and their high stability. Following the success of the femtoslicing installations at ALS, BESSY‐II, SLS and UVSOR, SOLEIL decided to implement a femtoslicing facility. Several challenges were faced, including operation at the highest electron beam energy ever, and achievement of slice separation exclusively with the natural dispersion function of the storage ring. SOLEIL's setup also enables, for the first time, delivering sub‐picosecond pulses simultaneously to several beamlines. This last feature enlarges the experimental capabilities of the facility, which covers the soft and hard X‐ray photon energy range. In this paper, the commissioning of this original femtoslicing facility is reported. Furthermore, it is shown that the slicing‐induced THz signal can be used to derive a quantitative estimate for the degree of energy exchange between the femtosecond infrared laser pulse and the circulating electron bunch.