Source Projects Research Articles

Design and practices at four European synchrotron radiation facilities

The European Directive 96/29/Euratom of 13/05/1996, based on the ICRP 60 Recommendations, defines basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionising radiation. Member states of the European Union have had to integrate these basic standards in their national legislation. Synchrotron radiation facilities are affected by this new radiation protection legislation. In the UK, the Daresbury Synchrotron Radiation Source (SRS) operates under the Ionising Radiations Regulations 1999, and the third generation Diamond Light Source (DLS) project is largely benefiting from their experience. In France, the ESRF case is presently being used to define detailed prescriptions, that will also apply to future sources in this country, for example the third generation light source Synchrotron Soleil, presently under construction. This paper summarises general policies and practices of these four SR facilities: SRS, European Synchrotron Radiation Facility (ESRF), DLS and Synchrotron Soleil.

The Spallation Neutron Source (SNS) project: a fertile ground for radiation protection and shielding challenges

The Spallation Neutron Source facility presently under construction in the USA consists of a front end, a linac, an accumulator ring, a target station and a neutron instrument hall, producing pulsed neutron beams driven by a proton beam of 1 GeV energy and 1.4 MW power with a repetition rate of 60 Hz. The layout of the facility and the radiation protection and shielding concept of the facility is laid out in numerous examples in a walk from the proton beam generation to the neutron utilisation.

The design and testing of a solid phantom for the verification of a commercial 3D seed reconstruction algorithm

Background and purposeTo test the implementation of a new solid phantom and to study the accuracy and the reliability of 3D seed reconstruction algorithms in prostate seed implants. Patients and methodsA solid phantom, the Kiel-phantom, to simulate prostate implants was designed. Several measurements were performed with this phantom to test the three-film seed reconstruction using a commercial planning system. ResultsPrecision of better than 0.1mm (SD) were found for seed combinations when source projections do not overlap. If seeds overlapped from two or more gantry angles, the software showed serious miscomputations with seed displacements of more than 30.0mm. ConclusionsSystematic measurements were carried out which demonstrated that the solid phantom can be an advantageous tool to increase the quality assessment for seed planning systems.

The Internet Chair

A pivot (swivel, rotating) chair is considered as an input/output device, an information appliance. The input modality is orientation tracking, which can dynamically select transfer functions used to spatialize audio in a rotation-invariant soundscape. In groupware situations, like teleconferencing or chat spaces, such orientation tracking can also be used to twist iconic representations of a seated user, avatars in a virtual world, enabling social situation awareness via coupled visual displays, soundscape-stabilized virtual source locations, and direction-dependent projection of non-omnidirectional sources. Using its audio output modality, the system can present unencumbered binaural sound with soundscape stabilization for multichannel sound image localization.

Modelling the accuracy of image data reprojection

Data transformation and reprojection are required for integrating remotely sensed data and geographical information system data into one map projection. At global or continental scales, the reprojection procedure may bring significant distortion of original pixel values. This research investigated a scale factor model to explain the amount of distortion. Specifically, model results were compared with experimental results. Six possible reprojections among the Equal-area Cylindrical projection, the Mollweide projection, and the Sinusoidal projection were tested. Results showed that reprojection accuracy could be explained using the ratios of scale factor changes along vertical and horizontal axes between source and target projections. The reprojection accuracy was the reciprocal of the maximum scale factor change either along the vertical or horizontal axis. However, the model accuracy was very sensitive to the skew effect that leads to significant increase of accuracy. Spatial autocorrelation and the number of unique pixels were found to affect the accuracy of reprojection. Considering the increasing use of global and continental datasets, this research suggests that reprojection of raster image data should be performed very carefully.

AUSTRON and its notable new features

The 10 Hz/0.5 MW AUSTRON neutron spallation source is dedicated for high-resolution structural and dynamical investigations of condensed matter and for new fundamental research with neutrons. New magnetic focusing and bunching systems are under development, which create additional intensity-gain factors of 10–20. Clean-room conditions including vibration, temperature and humidity control will improve the standard of neutron optical and neutron reflectometry experiments considerably. Narrow band neutron perfect crystal resonators and storage systems are foreseen for a novel beam tailoring. A dedicated new ultra-cold neutron station will open a new horizon for experiments in the sub-neV region. Recently, the project secured additional support of the Austrian Governmental Board for Research and Technological Development, which recommended the forced continuation of the project, the installation of a professional project group and the cooperation with the European Spallation Source (ESS) project and with the neighboring countries.

Source separation based processing for integrated Hall sensor arrays

Integrated arrays of Hall-type magnetic sensors are generally subject to significant crosstalk due to poor spatial selectivity of very closely spaced sensors. In this paper, we explore blind source separation as a signal processing technique to unmix a number of magnetic sources that impinge on the array. The processing consists of two stages: the first one estimates the source number and projects the observations on the signal subspace; the second stage is a source separation algorithm. Experimental results from a silicon array of Hall sensors, interfaced with a DSP, demonstrate real-time separation of two magnetic sources even under ill-conditioning of the mixing matrix.

The GNU GaMa Project - Adjustment of Geodetic Networks

The development of Free Software is a well established and successful phenomenon which could hardly exist without the Internet, where groups of programmers scattered all around the world are developing software. The idea of Free Software is highly attractive to talented creative students and can stimulate and support their profesional activities. The GNU GaMa [4] for adjusting of geodetic networks, with input data described in XML, is given here as a concrete example. Free Software [3] (or Open Source) projects need not be limited to software development but can generally cover any professional project based on free information exchange; a suggested example is the planned collection of model geodetic networks described in XML.

NSSA announces shull prize in neutron science at american conference on neutron scattering

The Neutron Scattering Society of America (NSSA) organized the first American Conference on Neutron Scattering (ACNS) from June 23–27, 2002 in Knoxville, TN. Attended by over 400 scientists and engineers from thirteen countries, the multi-disciplinary ACNS was sponsored by the national neutron centers with assistance from the National Science Foundation and the U.S. Department of Energy (DOE). The conference, the largest on neutron science ever held in the US., included more than 250 papers in the fields of biology, soft condensed matter, magnetism, instrumentation, fundamental neutron physics, chemistry, and industrial applications, all with the common thread of neutrons for research. The ACNS also served as a national meeting for present and potential users of the neutron research centers at Argonne, Chalk River, Los Alamos, National Institute for Standards and Technology (NIST), and Oak Ridge, and provided an opportunity to gain insight into the capabilities and available instrumentation at these facilities. Tours of the Spallation Neutron Source (SNS) Project and the High Flux Isotope Reactor at Oak Ridge National Laboratory were also available.

The ESS project is ready for a decision

The European Spallation Source (ESS) project entered a new phase with the presentation of the project at the ESS European Conference at the former House of Parliament in Bonn from May 16–17, 2002. The scientific case, the maturity of the proposed technical solution, and the backing by European users were clearly demonstrated at this meeting. It was attended by about 900 participants from twenty different European countries. The largest group of participants was scientists (about 750), but politics, industry, and the press were also well represented.

Beijing hosts the first moderator-target planning meeting

The First Moderator-Target Planning Meeting for the Chinese Spallation Neutron Source (CSNS) Project took place from April 21–26, 2002, at The Institute of Physics, Chinese Academy of Sciences, Beijing, China. The idea of a Chinese Spallation Neutron Source for basic research germinated after a delegation led by Professor Yong-Xiang Lu, the President of the Chinese Academy of Sciences (CAS), visited the ISIS facility in July 2000. Subsequently, in 200 I, CAS and other organizations of scientific branches sponsored three meetings, which resulted in the submission of a proposal for a feasibility study of CSNS. The proposal was granted on the eve of 2002, hence began Phase I of the CSNS Project, charging the Institute of Physics (IoP) and Institute of High Energy Physics (IoHEP), both belonging to CAS, to complete a full design and feasibility study by 2003.

ESS plans taking shape

The European Spallation Source (ESS) project aims for a decision in 2003 to build a unique third generation neutron source, according to a schedule which will allow start of operation in 2010. That the ESS is in a very active state became evident at the 7th ESS General Meeting held at Seggau Castle in Styria, Austria, from September 26–29, 2001. About 130 participants and more than fifty oral presentations dealt with the design and technical aspects of the facility. The meeting focused on the progress of the ESS project and the efforts required to achieve the milestones. The first day was devoted to the pre-sentation of the American and Japanese projects, which are already under construction, and to an extensive overview of the status of the ESS project. The second day con-centrated on detailed technical pre-sentations and discussions of the ESS study. It was arranged in three parallel sessions-accelerator and ring, target stations and instrumentation. Leading experts in the fields chaired these sessions and presented summaries of them on the last day of the meeting. Science and science-political issues were also discussed.

The SNS Target Station Preliminary Title I Shielding Analyses

The Department of Energy (DOE) has given the Spallation Neutron Source (SNS) project approval to begin Title I design of the proposed facility to be built at Oak Ridge National Laboratory (ORNL). During the conceptual design phase of the SNS project, the target station bulk-biological shield was characterized and the activation of the major target station components was calculated. Shielding requirements were assessed with respect to weight, space, and dose-rate constraints for operating, shutdown, and accident conditions utilizing the SNS shield design criteria, DOE Order 5480.25, and requirements specified in 10 CFR 835. Since completion of the conceptual design phase, there have been major design changes to the target station as a result of the initial shielding and activation analyses, modifications brought about due to engineering concerns, and feedback from numerous external review committees. These design changes have impacted the results of the conceptual design analyses, and consequently, have required a re-investigation of the new design. Furthermore, the conceptual design shielding analysis did not address many of the details associated with the engineering design of the target station. In this paper, some of the proposed SNS target station preliminary Title I shielding design analyses will be presented. The SNS facility (with emphasis on the target station), shielding design requirements, calculational strategy, and source terms used in the analyses will be described. Preliminary results and conclusions, along with recommendations for additional analyses, will also be presented.

Spallation neutron source symposium held in Washington

An important step towards the construction of a new neutron source for the Unitedstates tookplaceonMarch3 and 4,1998. About 250 attendees representing all of the major US neutron scattering facilities joined forces to present a convincing case for the importance of neutron scattering research for science, education and industry. The $1.3 billion Spallation Neutron Source (SNS) project will be built by a consortium of Department of Energy (DOE) laboratories, Oak Ridge National Laboratory (ORNL), Brookhaven National Laboratory (BNL), Argonne National Laboratory (ANL). Los Alamos National Laboratory (LANL) and Lawrence Berkeley National Laboratory (LBNL). LBNL will be responsible for designing and building the SNS's front-end system, which includes an ion source, beam formation and control hardware, and low-energy beam transport and acceleration systems. LANL will be responsible for the linac, which accelerates the H-beam from 2.5 to 1000 million electron volts. ANL and ORNL will be responsible for developing the neutron scattering instrumentation and moderator designs. BNL will be responsible for the accumulator ring structure, which bunches and intensities the ion beam for delivery onto the mercury target to produce the pulsed neutron beams. ORNL will be responsible for the coordination, installation and operation of the new source, project management, conventional construction, and design and construction of the liquid mercury target.

Code-based analysis of the development effort of a large scale courseware project

This paper investigates proposed code-based measures for multimedia courseware as part of an on-going program of research into effort estimation models. The proposed code-based size measures are analysed using source code and project data from WinEcon courseware written in the ToolBook authoring language. Statistical analysis of a priori, ToolBook specific and portable subsets of 47 code measurements are presented along with proposed predictive models of courseware development effort based on a priori, best subset and portable subset modelling assumptions.

Local interstellar matter and interstellar bubbles

Abstract Giant bubbles in nearby galaxies and our Galaxy are observed in optics, radio, and X-rays and have different sizes and origins. The largest ones inside the region occupied by the spiral structure have diameters less than 300-400 pc. The Cygnus Superbubble is not an entity, but represent a result of projection of many sources onto the sky. X-ray emission from bubbles blown by stellar winds has been predicted in the 1960s. The first Einstein data did not indicate any X-ray flux from Sh308 and RCW58. The most promising stellar wind nebula for X-ray observations is NGC 6888 and processing Einstein archival data reveals a soft X-ray emission whose flux is about 1/10 of the predicted one. A more careful modelling reduces the discrepancy down to a factor of 2 or 3. The local stellar matter is an old giant bubble around the Sco-Cen stellar association. There are many cold and warm gas clouds inside the bubble. The Sun is probably isolated from the bubble by the Local Cloud. Loop I is an old SNR inside th...

Vibration analysis of the photon shutter designed for the advanced photon source

Abstract The photon shutter is a critical component of the beamline front end for the 7 GeV Advanced Photon Source (APS) project, now under construction at Argonne National Laboratory (ANL). The shutter is designed to close in tens of milliseconds to absorb up to 10 kW heat load (with high heat flux). Our shutter design uses innovative enhanced heat transfer tubes to withstand the high heat load. Although designed to be lightweight and compact, the very fast movement of the shutter gives rise to concern regarding vibration and dynamic sensitivity. To guarantee long-term functionality and reliability of the shutter, the dynamic behavior should be fully studied. In this paper, the natural frequency and transient dynamic analysis for the shutter during operation are presented. Through analysis of the vibration characteristics, as well as stress and deformation, several options in design were developed and compared, including selection of materials for the shutter and structural details.

Optimising a High-Current Injector to Incorporate a Fast Beam Kicker

In addition to the requirement that the beam current limit imposed by space charge forces be as high as possible, provision should also be made in the injector for fast switching of the high-power beam. The intolerableness of beam losses in a high-current linear accelerator, such as proposed for the German spallation neutron source (SNQ) project, requires that the beam switching occurs cleanly between the beam bunches. The method of accomplishing this technically demanding beam switching is limited by the constraints on the injector chain such as the final energy and operating frequency. These boundary conditions, plus the choice of ion source voltage also come to bear on the current limit in the injector. In the SNQ the injector is asked to supply 200 mA of protons at 200 MHz at an energy of 2 MeV, while the ion source voltage has been chosen to be 50 keV. In order to satisfy all the constraints on the injector and at the same time deliver the maximum current, a frequency jump becomes necessary. The requirements for rf power efficiency in the high-energy linac also demand that all rf buckets be filled. A funneling scheme has been proposed for the SNQ wheremore » this can be achieved by doubling the current and bunch frequency from a pair of injectors operating at half the frequency. A new technique is also put forward in this paper for debunching a beam at an intermediate energy between two RFQ accelerators allowing an arbitrarily large frequency transition to be made between the two RFQ's and raising the current limit even further.« less

Recovered-sulfur: a constraint or a relief for future hydrocarbon related energy technologies?

Summary All over the world where large tonnages of recovered sulfur are being produced as a result of sweetening operations at existing and coming natural-gas-exploitation projects a first order oversupply problem has to be overcome. This problem will be the more overstressed by the probability of more sulfur being recovered as a result of world environmental legislation targeted at power-plant stack-gas emissions and by the expected growth of recovered sulfur supplied following commercialization of projects for synthetic natural gas, coal liquefaction and other alternative energy sources. For the past two years a programme has been underway of the Netherlands Organization for Applied Scientific Research in assessing sulfur related subjects with interfaces to energy, materials, pollution and implementation. Sulfur proved to be a promising composite-filler with extraordinary characteristics as far as recycling, water resistance, handling etc. is concerned. For both a near and a far future an energy technology based on sulfur related primary energy resources seems possible for the so-called underdeveloped as well as the developed countries.