[Show abstract][Hide abstract] ABSTRACT: The European XFEL is a 3.4 km long X-ray Free Electron Laser in the final construction and commissioning phase in Hamburg. It will produce 27000 bunches per second at 17.5 GeV. Early 2015 a first electron beam was produced in the RF-photo-injector and the commissioning of consecutive sections will follow during this and next year. The huge number and variety of devices for the accelerator, beam line, experiment, cryogenic and facility systems pose a challenging control task. Multiple systems, including industrial solutions, must be interfaced to each other. The large number of bunches requires a tight time synchronization (down to picoseconds) and high performance data acquisition systems. Fast feedbacks from front-ends, the DAQs and online analysis system with a seamless integration of controls are essential for the accelerator and the initially 6 experimental end stations. It turns out that the European XFEL will be the first installation exceeding 2500 FPGA components in the MicroTCA form factor and will run one of the largest PROFIBUS networks. Many subsystem prototypes are already successfully in operation. An overview and status of the XFEL control system will be given.
[Show abstract][Hide abstract] ABSTRACT: The collaboration work between the Stockholm University and DESY in Hamburg regarding the European XFEL is among other things aiming towards to provide access methods to the accelerator control system for the European XFEL project with the possibility of a secure and reliable access from remote places. The requested expansion of the control system has been designed as an extra layer for control and data transmissions integrated with systems for authentication and authorization. This makes it possible to have these remote access methods working side by side with more conventional access methods in the control system. This gives you the possibility to access the control system remotely with traditional, already in use rich clients implemented in Java and expanded with an extra layer for the remote communication or you can use other clients in the future, e.g. web applications. A key focus here is to implement these requirements and at the same time achieve good performance in a secure and reliable way. In this paper we will discuss how we implement these requirements, what parameters and security measures we are using in order to implement a reliable, secure and easy to use secured access layer and how it is integrated to the accelerator control system. The system is designed as a Service-Oriented Architecture (SOA) and implemented with the latest web service technology available at present in order to connect the different nodes such as control system nodes, application servers and different clients for control and monitoring with quality of service (QoS). The architecture and the chosen access security manager (OpenSSO) for authentication and authorization will be described in its parts and how they are integrated. We will present our experiences of the architecture so far, what design choices we have found suitable in order to meet the requirements of a modern control system and what performance we have achieved when transporting data and commands in a reliable wa- .
[Show abstract][Hide abstract] ABSTRACT: Embedded devices for control and monitoring are becoming more powerful as technology evolves. It is common that these embedded devices are communicating through a local area network with other, sometimes more powerful, nodes for receiving and distributing commands and data gathering. This distributed system can then be connected to other systems over the Internet for data exchange, remote control and monitoring. It is essential in such complex environment that the users are authorized and authenticated as users of the system, and that these security credentials can be easily managed. But this is not enough since not all commands are suitable to be executed in every status of a complex system and by all users from all locations. The wrong command pattern or security policy could potentially cause great damage to the system being controlled. We are developing a system allowing remote monitoring and control of the European XFEL projects accelerators control system DOOCS (see doocs.desy.de). This remote system uses a service oriented architecture based on web services for communication between its nodes. The interface to the underlying classical accelerator control system will be implemented on a central server, whereby any remote access can be audited and controlled. To meet the mentioned requirements for security and safe control patterns, we found it necessary to add a security layer. We decided to implement the OpenSSO package from Sun in our distributed system for authentication and authorization, to make certain that only authorized users can execute commands according to the allowed policy, based on user credentials, location and system status.
No preview · Article · Oct 2009 · IEEE Nuclear Science Symposium conference record. Nuclear Science Symposium
[Show abstract][Hide abstract] ABSTRACT: Remote control systems are becoming more and more important to give us the flexibility to control facilities, provide assistance and intervene in case of problems at any time and from every place. As a global operating group CALICE  with approx. 220 members worldwide is dependent on using a remote control system for shifts and monitoring of the data taking. CALICE has at present installed its detector at Fermilab, Chicago, where will run test beam experiments for the next year. The components of the remote control system and kind of use are presented here.
[Show abstract][Hide abstract] ABSTRACT: The European X-ray Free Electron Laser Project (XFEL), to be built at the DESY laboratory in Hamburg, Germany, will have a highly complex system for data acquisition and control. To allow access to the low level, embedded subsystems of the accelerator by high level applications (e.g. web browsers), we have developed a facade based architecture serving as an interface service, which acts as a bridge between the native DOOCS (distributed object oriented control system) communication layers and the web service oriented world. The aim of the first stage of the project is to show that such a gateway between the classical hardware oriented control system architecture and the modern service oriented web technologies is not only possible but also offers new ways for configuring and managing the huge amount of hardware components of this unique facility. The architectural layout of this novel integration between two such opposed worlds together with the first performance results will be presented.
No preview · Article · Oct 2008 · IEEE Nuclear Science Symposium conference record. Nuclear Science Symposium
[Show abstract][Hide abstract] ABSTRACT: Free electron LASer in Hamburg (FLASH) at DESY is a user facility with laser-like radiation source in the VUV and soft X-ray range. It is also a pilot facility for the future XFEL. A fast data acquisition system (DAQ) to support the accelerator operation and the user experiments was developed. The system collects data from hundreds of ADC channels in the range of 1 M up to 2 G samples per second. In addition it allows collecting images from digital video cameras. All the data is collected in a shared memory of a central multiprocessor computer. Several processes are used to calculate e.g., the orbit, energy or photon flux, or are used as feedback loops to improve the stability of the linac. A long time archiving of the collected data from the accelerator and from the FEL experiments on a 24 TB disk and finally on a tape is provided. The whole system is integrated in the DOOCS control system of FLASH. It is a novel approach to combine a fast DAQ system with a accelerator control system.
Full-text · Article · Mar 2008 · IEEE Transactions on Nuclear Science
[Show abstract][Hide abstract] ABSTRACT: The Free Electron Laser in Hamburg (FLASH(1)) at DESY is a user facility. It produces laser light of short wavelengths from the extreme ultraviolet down to soft X- rays. To study, monitor and document the machine performance and parameters and also to collect the results of the user experiment measurements a fast data acquisition (DAQ (2)) system has been developed. A shared memory based buffer manager is the heart of the system. It arranges collected data as events for every LINAC shot. All events can be read by different consumers simultaneously. LINAC feedback and monitoring processes as well as experiment middle layer servers are typical clients of the buffer manager. Any client can also generate its own data and insert it into the same event or produce its own one. The paper will focus on the detailed implementation of the buffer manager and its main features. The experience and the achieved performance will be covered as well.
[Show abstract][Hide abstract] ABSTRACT: We report results on the performance of a free-electron laser operating at a wavelength of 13.7 nm where unprecedented peak and average powers for a coherent extreme-ultraviolet radiation source have been measured. In the saturation regime, the peak energy approached 170 νJ for individual pulses, and the average energy per pulse reached 70 νJ. The pulse duration was in the region of 10 fs, and peak powers of 10 GW were achieved. At a pulse repetition frequency of 700 pulses per second, the average extreme-ultraviolet power reached 20 mW. The output beam also contained a significant contribution from odd harmonics of approximately 0.6% and 0.03% for the 3rd (4.6 nm) and the 5th (2.75 nm) harmonics, respectively. At 2.75 nm the 5th harmonic of the radiation reaches deep into the water window, a wavelength range that is crucially important for the investigation of biological samples.
[Show abstract][Hide abstract] ABSTRACT: Future accelerators and experiments are operated by large international collaborations and typically by dispersed teams of experts. The facilities will be operated over many years and even decades. It will be prohibitive to maintain a complete staff of experts at the site. The load of regular visits of the site is tremendously eased when experts can take action remotely. The demand for reliable remote monitoring and control is thus paramount. This paper describes a comprehensive solution which is being provided by the GANMVL-collaboration within EuroTeV. An important feature of the toll is that the implementation details are well hidden from the user to increase the public acceptance. The tools employed are based on web-browsers granting access to VNC, to VRVS and in the future EVO, to facility internal web-pages, to cameras and allow to control instruments. They include Single Sign On authentication so that security requirements can be met. Using standard interfaces the user need not be concerned with the technology of the instruments. The paper will include a demonstration of the current status of development.
[Show abstract][Hide abstract] ABSTRACT: Many scientific disciplines ranging from physics, chemistry and biology to material sciences, geophysics and medical diagnostics need a powerful X-ray source with pulse lengths in the femtosecond range [1-4]. This would allow, for example, time-resolved observation of chemical reactions with atomic resolution. Such radiation of extreme intensity, and tunable over a wide range of wavelengths, can be accomplished using high-gain free-electron lasers (FEL)[5-10]. Here we present results of the first successful operation of an FEL at a wavelength of 32 nm, with ultra-short pulses (25 fs FWHM), a peak power at the Gigawatt level, and a high degree of transverse and longitudinal coherence. The experimental data are in full agreement with theory. This is the shortest wavelength achieved with an FEL to date and an important milestone towards a user facility designed for wavelengths down to 6 nm. With a peak brilliance exceeding the state-of-the-art of synchrotron radiation sources  by seven orders of magnitude, this device opens a new field of experiments, and it paves the way towards sources with even shorter wavelengths, such as the Linac Coherent Light Source  at Stanford, USA, and the European X-ray Free Electron Laser Facility  in Hamburg, Germany.
Full-text · Article · Nov 2005 · The European Physical Journal D
[Show abstract][Hide abstract] ABSTRACT: The VUV-FEL is a free electron laser user facility being commissioned at DESY. It is based on the TTF-FEL, which was in operation until end of 2002 providing a photon beam for two pilot experiments in the wavelength range of 80 to 120 nm. In its final configuration, the new VUV-FEL is designed to produce SASE FEL radiation with a wavelength down to 6 nm with high brilliance. The commissioning started in fall 2004, and in January 2005 succeeded in first lasing in the SASE mode at a wavelength of 32 nm with a radiation power close to saturation. This is a major milestone of the facility and of SASE FELs in general. This contribution reports on the present electron linac driving the FEL, on properties of the electron beam and on the characterization of the FEL photon beam.
[Show abstract][Hide abstract] ABSTRACT: For the VUV-FEL (Vacuum-Ultraviolet Free Electron Laser) at DESY a 1 GeV superconducting LINAC (1) is used and presently being commissioned. The control system of the LINAC consists of 900 fast and 500 slow data channels producing up to 100 MByte/s of data depending on the LINAC operation mode. To study, control and archive the machine status and performance, a data acquisition system (DAQ) has been developed which allows storing machine parameters together with user experiment data. The system will provide the ability to correlate easily the accelerator status with experimental data on a bunch-by-bunch basis. The paper gives an overview on the architecture of the DAQ system and describes its main components in more detail.
[Show abstract][Hide abstract] ABSTRACT: The Free-Electron Laser (FEL) at the TESLA Test Facility at DESY operates in the self-amplified spontaneous emission mode and generates sub-100-fs radiation pulses in the vacuum ultraviolet spectral region. During operation in the saturation regime, radiation pulses with GW peak power are produced. The statistical properties of the FEL radiation have been studied for different amplification regimes as well as behind a narrow-band monochromator and found to be in good agreement with the results of numerical simulations. Information about the spectral and temporal structure of the FEL radiation has been deduced from the statistical properties. The pulse duration of the FEL radiation can be varied by tailoring the electron bunch that drives the FEL.
Full-text · Article · Jul 2003 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: Two 2×7-cell Nb superstructures have been tested with beam during the last TESLA Test Facility (TTF) linac run in summer 2002. The structures have been operated at 2 K in the standard TTF cryomodule and have been installed in the linac after the injector. We report on the bunch-to-bunch energy stability test which showed that energy stored in the superstructure could be refilled in the time between two passing bunches. The goal to keep the bunch-to-bunch energy stability below 5·10<sup>-4</sup> has been achieved.
[Show abstract][Hide abstract] ABSTRACT: After three years of preparation, two superstructures, each made of two superconducting 7-cell weakly coupled subunits, have been installed in the TESLA Test Facility linac (TTF) for the cold- and beam test. The energy stability, the HOMs damping, the frequency and the field adjustment methods were tested. The measured results confirmed expectation on the superstructure performance and proved that alternative layout for the 800 GeV upgrade of the TESLA collider, as it was proposed in TDR, is feasible. We report on the test and give here an overview of its results which are commented in more detail elsewhere in these Proceedings.