Harald Kleines

KWS-1 high-resolution small-angle neutron scattering instrument at JCNS: current state

The KWS-1 small-angle neutron scattering (SANS) instrument operated by the Julich Centre for Neutron Science (JCNS) at the research reactor FRM II of the Heinz Maier-Leibnitz Zentrum in Garching near Munich has been recently upgraded. The KWS-1 instrument was updated, from its active collimation apertures to the detector cabling. Most of the parts of the instrument were installed for the first time, including a broadband polarizer, a large-cross-section radio-frequency spin flipper, a chopper and neutron lenses. A custom-designed hexapod in the sample position allows heavy loads and precise sample positioning in the beam for conventional SANS experiments as well as for grazing-incidence SANS under applied magnetic field. With the foreseen in situ polarization analysis the main scientific topic of the instrument tends towards magnetism. The performance of the polarizer and flipper was checked with a polarized 3He cell at the sample position. The results of these checks and a comparison of test measurements on a ferrofluid in a magnetic field with polarized and nonpolarized neutrons are presented.

SPHERES, Jülich's high-flux neutron backscattering spectrometer at FRM II

SPHERES is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Jülich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 μeV, a dynamic range of ±u200931 μeV, and a signal-to-noise ratio of up to 1750:1.

Performance Aspects of PROFINET IO

Recently, the complex PROFINET CBA (component based automation) has been supplemented by the simplified PROFINET IO standard. PROFINET CBA defines a vendor-independent engineering model covering plant-wide automation and uses a component/container approach. Contrary to this, PROFINET IO aims at decentral periphery scenarios. Analogous to PROFIBUS DP it is based on a modular device model. Functionally, PROFINET IO can be considered as an Ethernet-based fieldbus. It is expected that PROFINET IO will play a major role on the PLC market since it is a possible replacement for PROFIBUS DP. The paper introduces the PROFINET technology and discusses performance aspects. Measurement results are presented.

Integration of industrial automation equipment in experiment control systems via PROFIBUS-developments and experiences at Forschungszentrum Julich

PROFIBUS, being a national German (DIN 19245) and an European (EN 50170) standard, has become the most widely accepted modern fieldbus technology in Europe. It is expected to take a similar role on the world market, since the IEC standardisation efforts for a common international fieldbus failed recently. A major reason for its success is the technological and functional scalability based on a common core. Now, a wide range of PLCs as well as low cost process I/O is available (also from leading manufacturers like Siemens) which enable easy interfacing. ZEL, the central electronics facility of Forschungszentrum Julich, has decided to use predominantly industrial components (PLCs, I/Os, etc.) in the front end of slow control systems for physics experiments.

Measurement of real-time aspects of Simatic/spl reg/ PLC operation in the context of physics experiments

Today, most slow control systems for physics experiments at Forschungszentrum Ju/spl uml/lich are implemented with Programmable Logic Controller (PLC) technology and fieldbus systems. In many cases, even deterministic response is required from the PLCs. This raises the question about the real-time performance that can be expected from a PLC. Response-time measurements of Simatic/spl reg/ PLCs-manufactured by the world market leader Siemens-are presented. Influence of program structure and hardware configuration on performance and deterministic behavior of a PLC is discussed.

The new DAQ system for WASA at COSY

For the operation of the WASA (Wide Angle Shower Apparatus) detector system at the Cooler Synchrotron COSY in Forschungszentrum Julich (FZJ) a new DAQ system has been developed, which conforms to the third generation of the DAQ systems at COSY. This comprises new readout electronics based on an optimized parallel bus with LVDS technology and FPGA-controlled event and buffer management. The new DAQ system has been successfully commissioned in autumn 2006. Further developments aiming at performance optimizations are in progress. The implementation status is presented and performance issues are discussed.

New synchronisation system for experiments at COSY

To improve existing experiments at COSY a new DAQ system is currently under development. It is also well suited to the requirements of WASA at COSY after its transfer from CELSIUS. The DAQ modules are scattered to about 10..20 crates and are able to digitize and store several thousands events before a computer engagement is required. Therefore we need a purely hardware based synchronisation system. The synchronisation system consists of one master module and several output modules housed in a proprietary LVDS crate. It communicates over point to point links with the crate controllers

Development of a High Resolution TDC Module for the WASA Detector System Based on the GPX ASIC

A high resolution time to digital conversion (TDC) module has been developed for the time-stamping of plastics scintillator signals in the WASA detector system. The module is designed in 6U Eurocard form factor for a proprietary optimized backplane bus with LVDS technology. It provides 64 channels and is based on the GPX ASIC from acam-messelectronic gmbh. In the selected mode the GPX has 8 input channels with a resolution up to 81 ps. Design issues and preliminary results of the performance of the module are discussed.

Application of industrial standard process control equipment in neutron scattering experiments

Based on thorough experiences with distributed experiment control systems and fieldbus applications we are developing a control system especially targeted at neutron scattering experiments. Main characteristic is that front-end equipment and control machine are coupled by the industrial fieldbus standard PROFIBUS (DIN 19245, EN 50170). This significantly reduces the amount of cabling necessary. Further, it provides the proven error recovery and diagnostic features of an industrial fieldbus to the experiment control area. Front-end equipment comprises industrially available components like SIEMENS ET200 peripheral devices, PLCs and encoders (Heidenhain). For cost-sensitive stepper motor control a low-end motor controller from University of Gottingen is being interfaced directly to PROFIBUS. Widely available SIEMENS-SMP equipment can be coupled by a PROFIBUS-SMP interface developed at our institute. The controlling master is an Intel PC running a diskless Linux version, equipped with a home-made PROFIBUS controller in CompactPCI formfactor. As software interface to control applications the TACO framework developed at ESRF is employed. Device servers in terms of the TACO client-server architecture have been created, allowing access to the functions of the control system at different levels, from raw PROFIBUS accesses up to complete motor control with position encoder feedback.

Access to industrial process periphery via Java for process control (JFPC)

Using Java for real world I/O requires its availability in real-time (RT) systems. It is widely accepted that in a plain Java environment, RT characteristics get lost and the required programming interfaces are missing. So there are several ongoing standardization efforts for RT Java. An essential aspect (also important for non-RT systems) is the access to external I/Os. The Siemens product Java for process control (JFPC), which is based on the ideas of OLE for process control (OPC) addresses this aspect. It is available under the proprietary RT kernel RMOS and under Windows NT. Forschungszentrum Julich developed different JFPC providers in order to access industrial components via PROFIBUS DP using an experimental version of JFPC under Linux. The paper presents the status of the different standardization efforts for RT Java and the key features of JFPC. It describes the implementation of a JFPC provider for PROFIBUS DP and shows how it can be used to access industrial sensors and actuators. Experiences and performance results are discussed.