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The F-18, produced during nova explosions, is the main responsible for the 511 keV gamma-ray emitted during the outburst that could be detected with satellite missions or future gamma-ray telescopes. In spite of many experimental efforts, the amount of F-18 synthesized still suffers from large uncertainties concerning mainly the F-18(p, alpha)O-15 reaction. We report here on a new direct measurement of the F-18(p, alpha)O-15 cross section recently carried out at the RIB facility at Louvain-la-Neuve. Cross section data down to a center-of-mass energy of 400 keV have been obtained using an isobarically pure F-18 beam ( averaged intensity of the order of 10(6) pps) and a thin polyethylene target. The reaction products were detected using the multi-strip detector array LEDA. The cross section data are analysed in the framework of the R-matrix model. Our main aim is to determine the interference sign between three 3/2(+) resonances above threshold that can significantly affect the extrapolation of the F-18(p, alpha)O-15 cross section to the energies relevant for novae, and thus, the modeling of nova explosions.

In this paper we discuss recent work to further improve our superconducting (SC) ADS driver linac design. Our design assumes use of the 6.7-MeV LEDA RFQ as an injector to the SC driver linac. We have examined the feasibility of accelerating a 20-mA CW beam to 600 MeV using only 350-MHz SC multi-spoke resonator cavities operating at 4 K. Replacing the 2 K, 700-MHz SC elliptical cavity sections with spoke resonators has several advantages, including reduced cryo-plant operating cost and an improved real-estate accelerating gradient due to the longer active lengths of the 350-MHz cavities. We discuss the details of the new design layout and beam dynamics simulations, including effects due to operational and alignment errors. Preliminary cavity modelling results for the proposed five-gap spoke resonators are also discussed. This accelerator design would be appropriate as a driver linac for applications such as waste transmutation, fusion materials testing, etc.

Los Alamos has been an active participant in the development of high-intensity accelerators, including the RFQ, LAMPF with the innovation of a CCL structure, and more recently, LEDA with a 100-mA CW beam. Participation in technology development related to high-intensity applications such as transmutation of waste, and others, remains a strong interest at Los Alamos. Past efforts leading up to present programmes are discussed. These programmes include development of novel normal and superconducting structures, RF power systems, beam dynamics, beam diagnostics and general system considerations...

Recent surveys of the Local Group spiral Galaxies M31 and M33 with XMM-Newton yielded a large number of X-ray sources. As part of the effort to identify and classify the objects responsible for this X-ray emission, we have obtained optical spectra of the brightest optical counterparts of the identified X-ray sources, using the 1.3m Skinakas Telescope. Most of these objects are foreground star candidates. The purpose of the present study is to confirm this identification and to explore the compatibility between the optical spectral classification and the observed X-ray properties of the sources. We have obtained optical spectra for the 14 brightest optical counterparts of X-ray sources identified by XMM-Newton in the direction of M31 and for 21 optical counterparts in the direction of M33, using the 1.3m Skinakas telescope in Crete, Greece. All of the M31 sources and all but one of the M33 sources were confirmed to be foreground stars, of spectral types between A and M. One of the stars is a late M dwarf with H-alpha emission, a flare star, also displaying strong X-ray variability. One of the M~33 sources (lying within the D25 ellipse) corresponds to a previously known background galaxy, LEDA 5899., 9 pages, 12 figures, accepted in A&A

Eighteen carcasses were used for investigations of meat yield for pork prosciutto production (primal cut loin - M. longissimus lumborum et thoracis). Average weight of live pigs was 102 kg. Average weight of warm primary dressed carcasses was 87.6 kg, chilled - 86.1 kg (weight loss during chilling - 1.71%), whereas average carcass yield was 84.41%. Average shares of total meat yield for pork prosciutto production was - in chilled carcass weight 6.47% (left sides) and 6.60% (right sides); in crude loin weight - 42.12% (left sides) and 40.98% (right sides). U radu su izneseni podaci o prinosu mesa, pre svega osnovnog dela slabina i leđa (M. longissimus lumborum et thoracis), koje se koristi za proizvodnju svinjske pršute. Za ispitivanja je korišćeno 18 trupova svinja prosečne mase pre klanja 102 kg. Prosečna masa primarno obrađenih toplih trupova iznosila je 87,6 kg, a ohlađenih 86,1 kg (gubitak mase tokom hlađenja 1,71%), dok je prinos trupa iznosio 84,4%. Prosečan prinos obrađene muskulature slabina i leđa, u odnosu na masu ohlađene polutke, iznosio je 6,47% za leve i 6,60% za desne polutke; a u odnosu na masu neobrađenih leđa, 42,12% za leve i 40,98% za desne polutke.

Context. The detection, thanks to the INTEGRAL satellite, of a number of new hard X-ray sources calls for the identification of their nature by means of observations at longer wavelengths. Aims. In our continuing campaign to identify longer-wavelength counterparts of these newly-discovered hard X-ray sources detected by INTEGRAL, we observed the putative optical counterparts of seven southern sources at the South African Astronomical Observatory and at the European Southern Observatory. Methods. Optical spectroscopy was performed on all candidates of these X-ray sources. For two of these objects, optical photometry was also acquired. Results. These observations firmly established the nature of four of these sources: we found that IGR J10404-4625 (=LEDA 93974), 4U 1344-60 and IGR J16482-3036 are Active Galactic Nuclei (AGNs) at redshifts z = 0.0237, 0.013 and 0.0313, respectively, and that 2RXP J130159.6-635806 is a Galactic High-Mass X-ray Binary (HMXB). We also give possible optical identifications for three further objects, namely IGR J11215-5952, IGR J11305-6256 and IGR J16207-5129, which are consistent with being Galactic HMXBs. Physical parameters for these objects are also evaluated by collecting and discussing the available multiwavelength information. Conclusions. The detection of four definite or likely HMXBs out of seven objects in our sample further stresses INTEGRAL's crucial contribution in hunting this class of object. Also, the determination of the extragalactic nature of a substantial fraction of the INTEGRAL survey sources underlines the importance of hard X-ray observations for the study of background AGNs located beyond the 'Zone of Avoidance' of the Galactic Plane., 12 pages, 2 figures, 2 tables, accepted for publication on A&A, main journal. The quality of Fig. 1 was degraded to fit the arXiv uploads size limits. Abstract changed to comply with the new format of A&A abstracts; added a note in proof concerning IGR J11305-6256

We present a catalog of near-infrared properties of LEDA galaxies, using the full resolution images from the DENIS survey. The fluxes are integrated in eight homothetic ellipses defined by their proper axis ratio, position angle and major axis (up to twice the blue diameter at the isophote 25 mag arcsec-2) extracted from the LEDA database. From the curves of growth in I, J and Ks photometric bands, we estimated different apparent magnitudes and diameters (``total'', ``Kron'' and ``isophotal''). Isophotal parameters refer to the limiting surface brightnesses: 22.5 I mag arcsec-2, 21.0 J mag arcsec-2 and 20.0 Ks mag arcsec-2 for the three photometric bands, respectively. The result is a catalog of 753 153 objects (among which there are 508 224 galaxies, 34 449 probable galaxies and 210 480 galaxies to be confirmed). The catalog gives about (the figures vary, depending on the considered magnitude or diameter): 668 000 I-band magnitudes, 576 000 J-band magnitudes, 357 000 Ks-band magnitudes and 452 000 I-band diameters, 299 000 J-band diameters, 114 000 Ks-band diameters. The typical standard deviations for I, J and Ks magnitudes are 0.14, 0.15 and 0.25, respectively, for magnitudes limited at I=16, J=15 and Ks=14. The contamination by superimposed objects probably remains the major source of problems and could require future improvement. The completeness limits in magnitude are about: 15.5, 14.5 and 13 in I, J and Ks, respectively. Full Catalog illustrated in Table \ref{cata} is only available in electronic form at CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/430/751

We formally verify the result checker for priority queues that is implemented in LEDA. We have developed a method, based on the notion of implementation, which links abstract specifications to concrete implementations. The method allows non-determinism in the abstract specifications that the concrete implementations have to fill in. We have formally verified that, if the checker has not reported an error up to a certain moment, then the structure it checks has behaved like a priority queue up to that moment. For the verification, we have used the first-order theorem prover Saturate.

The ESA initiative for an international Moon Programme proposes a four phase approach to the end goal of establishing a man-tended scientific outpost on the Moon. The first phase of the programme calls for the detailed exploration of the moon to establish its chemical inventory and environment, to pave the way for future phases. The first mission of phase 1 is named LEDA “Lunar European Demonstration Approach”. It has the task of establishing within Europe the technology of soft landing a payload of about 200 kg on the lunar surface. LEDA will land close to the Lunar south pole. The proposed payload is a rover for remote investigation, a robotic arm for sample acquisition and a soil analysis and processing facility. The programme is financially very modest, an ESA medium size mission, and will be launched by ARIANE 5 in a shared launch configuration in 2002 to 2003.

Our work goes towards answering the growing need for the robust and efficient manipulation of curved objects in numerous applications. The kernel of the CGAL library provides several functionalities which are, however, mostly restricted to linear objects. We focus here on the arrangement of conic arcs in the plane. Our first contribution is the design, implementation and testing of a kernel for computing arrangements of circular arcs.A preliminary C++ implementation exists also for arbitrary conic curves. We discuss the representation and predicates of the geometric objects. Our implementation is targeted for inclusion in the CGAL library. Our second contribution concerns exact and efficient algebraic algorithms for the case of conics. They treat all inputs, including degeneracies, and they are implemented as part of the library SYNAPS 2.1.Our tools include Sturm sequences, resultants, Descartes' rule, andisolating points. Thirdly, our experiments on circular arcs show that our methods compare favorably to existing alternatives using CORE 1.6x and LEDA 4.5.

Estimating the domain of attraction (DA) of equilibrium points is a problem of fundamental importance in systems engineering. Several approaches have been proposed for the case of known polynomial systems allowing one to find the largest estimate of the DA (LEDA) for a given Lyapunov function (LF). However, the problem of estimating the robust DA (RDA), that is the DA guaranteed for all possible uncertainties in an uncertain system, it is still an unsolved problem. In this paper, some methods are proposed for dealing with such a problem in the case of systems depending polynomially in the state and in the uncertainty which is supposed to belong to a polytope. Specifically, the issue of estimating the robust LEDA (RLEDA), that is the intersection of all LEDAs in the uncertain system, is considered for common and parameter-dependent LFs, providing constant and parameter-dependent lower bounds through LMI optimizations. In order to obtain easy descriptions of the RLEDA in the case of parameter-dependent LFs, an LMI method for computing approximations with simple shape is presented.

As a predominant technique to estimate the cause and effect of Quality of Service (QoS) criteria in computer networks, simulations provide insight into how to most efficiently configure protocols to maximize the usage and to estimate the criteria for acceptable performance of network applications. This paper investigates the simulation of Genetic Algorithm-based network routing using Open Shortest Path First (OSPF) protocols. The simulator is implemented using LEDA (Library of Efficient Data types and Algorithms) [1] and the applicability of the library is examined in the context of Genetic Algorithms.

We argue that globular clusters (GCs) are good candidates for gravitational lenses in explaining quasar-galaxy associations. The catalog of associations (Bukhmastova 2001) compiled from the LEDA catalog of galaxies (Paturel 1997) and from the catalog of quasars (Veron-Cetty and Veron 1998) is used. Based on the new catalog containing 8382 pairs, we show that one might expect an increased number of GCs around irregular galaxies of types 9 and 10 from the hypothesis that distant compact sources are gravitationally lensed by GCs in the halos of foreground galaxies. The King model is used to determine the central surface densities of 135 GCs in the Milky Way. The distribution of GCs in central surface density was found to be lognormal., 22 pages, 4 figures

We are preparing the radio frequency quadrupole (RFQ) for the Low Energy Demonstration Accelerator (LEDA) to accelerate beam. The LEDA RFQ accelerates a 100-mA CW proton beam from 75 keV to 6.7 MeV. We report our experience with high-power RF conditioning the RFQ, first with one klystron and then with two klystrons. The RFQ will dissipate 1.2 megawatts of RF power at design fields. This 350-MHz CW RFQ has peak fields on the vane tips of 33 MV/m. The average power dissipation is 13 watts/cm/sup 2/ on the outer walls of the RFQ near the high energy end. The power from each klystron is split 4 ways to lower the stress on the RF windows. Each klystron can produce 1.3 megawatts of RF power.

The Low-Energy Demonstration Accelerator (LEDA) injector is designed to inject 75-keV, 110-mA, proton beams into the LEDA RFQ. The injector operation has been automated to provide long term, high availability operation using the Experimental Physics and Industrial Control System (EPICS). Automated recovery from spark-downs demands reliable spark detection and sequence execution by the injector controller. Reliable computer control in the high-energy transient environment required transient suppression and isolation of hundreds of analog and binary data lines connecting the EPICS computer controller to the injector and its power supplies and diagnostics. A transient suppression design based on measured and modeled spark transient parameters provides robust injector operation. This paper describes the control system hardware and software design, implementation and operational performance.

Beam diagnostic instrumentation is being developed for the LEDA, a 6.7-MeV, 100-mA-cw proton accelerator, presently being commissioned at the Los Alamos National Laboratory (LANL). This instrumentation will be the basis for much of the Accelerator Production of Tritium and the Spallation Neutron Source linac. Located in the LEDA injector and the high energy beam transport (HEBT) this initial instrumentation suite's purpose is to verify the RFQ pulsed and cw operation. The instrumentation include a series of DC, pulsed- and bunched-beam current measurements from which RFQ beam-transmission efficiency will be determined. Ionization-chamber beam loss measurements are mounted above the HEBT and provide input signals to a fast equipment protection system. Central beam phase and energy measurements provide RFQ longitudinal performance information. Beam position measurements provide information to properly center the beam within the HEBT beam pipe. Finally, two types of transverse profile measurements including a slow wire scanner and a video fluorescence monitor provide beam width and projection information in the LEDA HEBT. This paper will discuss these measurements developed for LEDA and summarize how they performed during RFQ verification experiments.

Initial commissioning of a 6.7-MeV 100-mA RFQ is underway. The RFQ is part of LEDA, the He injector for the Accelerator Production of Tritium (APT) project. To benchmark the RFQ performance, beam physics experiments will be done with low and high current beams for both pulsed and cw beam operation. Commissioning efforts thus far have been limited to low-current pulsed beam LEDA operation. Measurements to fully characterize the RFQ will ultimately include the dependence of RFQ beam transmission on RFQ vane voltage, input beam energy, input match, and input transverse centroids. Other commissioning measurements for the RFQ will include output beam energy, phase, noise, transverse profiles, and transverse RMS emittances. This paper contains initial LEDA RFQ commissioning results, including RFQ pulsed output beam currents up to 40 mA.

In modern industrial control, a relay experiment can be used for auto-tuning a PI controller. It gives the ultimate frequency and ultimate gain of the open loop system. Based on the ultimate gain and the ultimate frequency, the PI control parameters, the proportional gain, and the integration time, are determined. A relay experiment can be used to determine the sensitivity of a closed loop system against external disturbances. This paper addresses a method to estimate the sensitivity represented by the gain margin of a closed loop low-level RF (LLRF) control system based on the Matlab/Simulink model of the Low Energy Demonstration Accelerator (LEDA) RFQ. This paper discusses some of the modeling performed and our operational experience to date.

A vacuum control system has been developed for use on the Los Alamos National Laboratory continuous wave (cw) Low Energy Demonstration Accelerator (LEDA) proton injector. This paper summarizes hardware and software implementation to satisfy the following design criteria: (1) performs as a standalone system-no direct access to CPU/memory components by computer control hardware during normal operations, (2) has local (chassis) and remote control (EPICS & LabVIEW) capabilities, (3) is electrically isolated and filtered from electrical transients created from injector high voltage spark-downs to ground, and (4) incorporates fast protect and fail safe components.

The Low-Energy Demonstration Accelerator (LEDA) injector is designed to provide 75-keV, 110-mA, proton beams for the LEDA RFQ. After testing the LEDA injector using a 1.25-MeV, CW RFQ, we shortened the low-energy beam transport (LEBT) to 2.69 m, replaced the first LEBT solenoid with one that has a shorter length but the same focusing power, and installed and operated the LEDA injector in the beam tunnel. In this paper we use the TRACE, SCHAR, and PARMELA computer codes to model the proton beam for the as-installed LEBT and we compare the results of these simulations with the LEBT beam measurements. We use the computer code PARMTEQM to transport the SCHAR- and PARMELA- generated beams through the RFQ so that we can compare the predicted RFQ performance with the measured RFQ performance. For a 100-mA, 0.239-/spl pi/-mm-mrad input beam, PARMTEQM predicts the LEDA RFQ transmission will be 92.2%.

The learning design assistant LEDA provides an environment for the creation of structural register-transfer descriptions. LEDA's inputs constitute an algorithmic behavioral hardware description and a specification of the design goals. The designer uses LEDA as an extended design editor and selects a sequence of allocation operators called the design plan that create register-transfer components for a statement of the algorithm. LEDA's learning component creates from each plan a specific production rule which is generalized by use of an inductive learning mechanism that is tailored to the acquisition of design plans. Each time a rule matches on the selected statement LEDA proposes the execution of the corresponding design plan. In this way LEDA works as an apprentice system, adapts to the design style of the user, and supports the synthesis of the repeatedly occurring parts of algorithm descriptions. >

Multiparadigm programming is a term used to describe a style of software development that makes use of facilities originally designed in support of a number of different programming language paradigms. A conception of multiparadigm programming is illustrated by describing how various data structures can be implemented in Leda, a strongly typed compiled multiparadigm programming language. Specifically, a style of program development that draws upon features from a number of different programming language paradigms is illustrated. Aspects of imperative programming, object-oriented programming, functional programming, and logic (or relational) programming are used. It is shown how these various language paradigms can be integrated in a single problem domain, and how each can derive benefit from the others. The problem considered is the creation of a few simple data structures for lists and two-dimensional tables. The development of this example is used as a means to introduce Leda. >

International audience; We present the new catalog of principal galaxies (PGC2003). It constitutes the framework of the HYPERLEDA database that supersedes the LEDA one, with more data and more capabilities. The catalog is still restricted to confirmed galaxies, i.e. about one million galaxies, brighter than similar to 18 B-mag.In order to provide the best possible identification for each galaxy we give: accurate coordinates ( typical accuracy better than 2 arcsec), diameter, axis ratio and position angle. Diameters and axis ratios have been homogenized to the RC2 system at the limiting surface brightness of 25B - mag arcsec(-2), using a new method, the EPIDEMIC method. In order to provide the best designation for each galaxy, we collected the names from 50 catalogues. The compatibility of the spelling is tested against NED and SIMBAD, and, as far as possible we used a spelling compatible with both. For some cases, where no consensus exists between NED, SIMBAD and LEDA, we propose some changes that could make the spelling of names fully compatible.The full catalog is distributed through the CDS and can be extracted from HYPERLEDA.

Using well-defined selection criteria applied to the LEDA galaxy catalogue we have constructed a sample of elliptical galaxies that can be taken to lie in the field. Such criteria can easily be applied to theoretical simulations for direct comparison with observations. The variation of the number of `isolated' ellipticals with selection criteria is also investigated. A preliminary study of the environment of the field ellipticals shows that, in the mean, they are surrounded by a population of dwarf galaxies, out to projected radii of at least 500 kpc, with a radial density profile of $r^{-0.6\pm 0.2}$ and a luminosity function slope of $\alpha \sim -1.8$. The results are compared and contrasted to the satellite population around isolated spiral galaxies., Comment: 12 pages including 3 figures and 1 table, aastex preprint style, submitted to ApJ

Successful operation of the Accelerator Production of Tritium (APT) plant will require that accelerator downtime be kept to an absolute minimum. Over 230 separate 1 MW RF systems are expected to be used in the APT plant, making the efficiency and reliability of these systems two of the most critical factors in plant operation. The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for APT. The design of the RF systems used in LEDA has been driven by the need for high efficiency and extremely high system reliability. We present details of the high voltage power supply and transmitter systems as well as detailed descriptions of the waveguide layout between the klystrons and the accelerating cavities. The first stage of LEDA operations will use four 1.2 MW klystrons to test the RFQ and supply power to one test stand. The RFQ will serve as a power combiner for multiple RF systems. We present some of the unique challenges expected in the use of this concept.

Radio frequency (RF) windows are historically a point where failure occurs in input power couplers for accelerators. To obtain a reliable, high-power, 350 MHz RF window for the Low Energy Demonstration Accelerator (LEDA) project of the Accelerator Production of Tritium program, RF window prototypes from different vendors were tested. Experiments were performed to evaluate the RF windows by the vendors to select a window for the LEDA project. The Communications and Power Industries, Inc. (CPI) windows were conditioned to 445 kW in roughly 15 hours. At 445 kW a window failed, and the cause of the failure will be presented. The EEV windows were conditioned to 944 kW in 26 hours and then tested at 944 kW for 4 hours with no indication of problems.

This paper describes the beam-position measurement system being developed for the Low Energy Demonstration Accelerator (LEDA) and the Accelerator Production of Tritium (APT) projects at Los Alamos National Laboratory. The system consists of a beam-position monitor (BPM) probe, cabling, down-converter module, position/intensity module, on-line error-correction system, and the necessary control system interfaces. The modules are built on the VXI-interface standard and are capable of duplex data transfer with the control system. Some of the key, system parameters are: position-measurement bandwidth of at least 180 kHz, the ability to measure beam intensity, a beam-position measurement accuracy of less than 1.25 percent of the bore radius, a beam-current dynamic range of 46 dB, a total system dynamic range in excess of 75 dB, and built-in on-line digital-system-error correction.

A 20-MeV 100-mA-CW proton-accelerator, Low Energy Demonstration Accelerator (LEDA), is presently being developed, fabricated, and tested at Los Alamos National Laboratory (LANL). The beam diagnostic instrumentation for LEDA and the final 1700-GeV Accelerator Production of Tritium (APT) are classified into two categories: operation and characterization instrumentation. The operational instrumentation does not intercept or minimally-intercepts the beam and are sufficiently prompt and robust to provide accurate information to the operators and commissioners during full-current CW beam operation. The characterization instrumentation, primarily utilized during commissioning project-phases, operates under more traditional 100-mA-peak and approximately 0.1-mA-average beam-current conditions. This paper will review some of the LEDA and APT operational beam diagnostic instrumentation.

The computer codes TRACE and SCHAR model the Low-Energy Demonstration Accelerator (LEDA) low-energy beam transport (LEBT) for 75-keV, 110-mA, dc H/sup +/ beams. Solenoid-lens location studies verify that the proposed LEBT design gives a near-optimum match to the LEDA RFQ. The desired RFQ transmission (/spl ges/90%) and output emittance (/spl les/0.22 /spl pi/ mm mrad, transverse) are obtained when PARMTEQM transports the file for the SCHAR-generated optimum beam through the RFQ.

The codes PARMTEQM and RFQTRAK simulate the beam transport through the radio-frequency-quadrupole (RFQ) accelerator for the low-energy-demonstration accelerator (LEDA). They predict 95% transmission for a matched 110-mA proton beam with a normalized-RMS emittance of 0.02 mm mrad. RFQTRAK simulates the effects of arbitrary vane-tip misalignments. This RFQ includes some new features in its design. It consists of four resonantly coupled 2-m-long segments that make up its 8-m length. It has higher vane-gap voltages at the high-energy end than the low-energy end. The entrance end of the RFQ has lower transverse focusing strength to facilitate beam matching. The exit of the RFQ has a transition cell and a radial-matching section. The exit radial-matching section matches the beam into the following accelerator.

This paper describes the design and fabrication of a vacuum pumping system for the APT/LEDA (Low Energy Demonstration Accelerator) RFQ (Radio Frequency Quadrupole) linac. Resulted from the lost proton beam, gas streaming from the LEBT (Low Energy Beam Transport) and out-gassing from the surfaces of the RFQ cavity and vacuum plumbing, the total gas load will be on the order of 7.2/spl times/10/sup -4/ Torr-liters/sec, consisting mainly of hydrogen. The system is designed to pump on a continual basis with redundancy to ensure that the minimal "operating vacuum level" of 1/spl times/10/sup -6/ Torr is maintained even under abnormal conditions. Details of the design, performance analysis and the preliminary test results of the cryogenic pumps are presented.

This paper describes the specification, design and preliminary operation of the beam-position/intensity measurement module being built for the Low Energy Demonstration Accelerator (LEDA) and Accelerator Production of Tritium (APT) projects at Los Alamos National Laboratory. The module, based on the VXI footprint, is divided into three sections: first, the analog front-end which consists of logarithmic amplifiers, anti-alias filters, and digitizers; second, the digital-to-analog section for monitoring signals on the front panel; and third, the DSP, error correction, and VXI-interface section. Beam position is calculated based on the log-ratio transfer function. The module has four, 2-MHz, IF inputs suitable for two-axis position measurements. It has outputs in both digital and analog format for x- and y-position and beam intensity. Real-time error-correction is performed on the four input signals after they are digitized and before calculating the beam position to compensate for drift, offsets, gain nonlinearities, and other systematic errors. This paper also describes how the on-line error-correction is implemented digitally and algorithmically.

Beam diagnostics systems being designed for the Low Energy Demonstrator Accelerator (LEDA) at Los Alamos include beam synchronous-phase and beam energy measurements. The LEDA machine will utilize an RFQ front end operating at 350 MHz, followed by several 700-MHz DTL accelerating structures. Signals from cavity-field probes and beam image-current probes will be down-converted to 2 MHz for phase measurement in VXI modules. Each 2-MHz signal is sampled at 8 MHz with a 12-bit ADC and the resultant data stream is converted into I and Q components which update at a 2-MHz rate. The I and Q signals are then converted to a relative phase measurement. Each VXI module will contain four channels of phase measurement hardware which allow for two channels of differential-phase measurement. Low-noise AGC circuits will accommodate signal variations over a 64 dB dynamic range. An on-board calibration system provides a system absolute accuracy of /spl plusmn/1 degree. DSP filtering allows 200-kHz bandwidth measurements to be made with a resolution of

Multiparadigm programming languages have been envisioned as a vehicle for constructing large and complex heterogeneous systems, such as a stock market exchange or a telecommunications network. General-purpose multiparadigm languages, as opposed to hybrid multiparadigm languages, embody several prevalent programming paradigms without being motivated by a single problem. One such language is Leda, which embodies the foundational paradigms of imperative, functional, logic, and object-oriented programming. We explore aspects of solving complex problems using Leda, in order to illustrate the benefits of using a multiparadigm language in expressing solutions to complex systems. We claim that general-purpose multiparadigm programming languages like Leda greatly expedite solutions to a variety of complex problems.

Within the halo experiment presently being conducted at the Low Energy Demonstration Accelerator (LEDA) at Los Alamos National Laboratory, specific beam instruments that acquire horizontally and vertically projected particle-density distributions out to approximately 10/sup 5/:1 dynamic range are located throughout the 52-magnet halo lattice. We measure the core of the distributions using traditional wire scanners, and the tails of the distribution using water-cooled graphite scraping devices. The wire scanner and halo scrapers are mounted on the same moving frame whose location is controlled with stepper motors. A sequence within the Experimental Physics and Industrial Control System (EPICS) software communicates with a National Instruments LabVIEW virtual instrument to control the motion and location of the scanner/scraper assembly. Secondary electrons from the wire scanner 0.033-mm carbon wire and protons impinging on the scraper are both detected with a lossy-integrator electronic circuit. Algorithms implemented within EPICS and in Research System's Interactive Data Language subroutines analyze and plot the acquired distributions. This paper describes this beam profile instrument, describes our experience with its operation, compares acquired profile data with simulation, and refers to other detailed papers.

The LEDA RFQ is a 350-MHz continuous-wave (CW) radio-frequency quadrupole linac. LEDA is the low energy demonstration accelerator, a full power front-end prototype for the accelerator production of tritium (APT) linac. This machine has accelerated a 100-mA CW proton beam from 75 keV to 6.7 MeV. The 8-m-long RFQ accepts a dc, 75-keV, /spl sim/110-mA H/sup +/ beam from the LEDA injector, bunches the beam, and accelerates it to full energy with /spl sim/94% transmission. The output beam power is 670 kW. This RFQ consists of four 2-meter-long RFQs joined with resonant coupling to form an 8-meter-long RFQ. The resonant coupling improves the stability of both the longitudinal and transverse RF-field distribution in this long RFQ.

Two independent magnet and vacuum control systems were implemented in the Low-Energy Demonstration Accelerator (LEDA) facility. The first one, for the High-Energy Beam Transport (HEBT) in context of the Accelerator Production of Tritium (APT) project, used the in-house Experimental Physics and Industrial Control System (EPICS). The second one, for the high-power proton beam-halo experiment (HALO-Channel) as an extension to the existing accelerator, is based on commercial products (National Instruments, LabVIEW). This paper will evaluate our experience during implementation, operation, and maintenance of these systems. It will include a discussion of various problems encountered and solutions implemented.

The present configuration of the Low-Energy Demonstration Accelerator (LEDA) consists of a 75-keV proton injector, a 6.7-MeV 350-MHz cw radio-frequency quadrupole (RFQ) with associated high-power and low level rf systems, a 52-magnet periodic lattice followed by a short high-energy beam transport (HEBT) and high-power (670-kW cw) beam stop. The rms beam emittance was measured prior to the installation of the 52-magnet lattice, based on wire-scanner measurements of the beam profile at a single location in the HEBT. New measurements with additional diagnostic hardware have been performed to determine the rms transverse beam properties of the beam at the output of the 6.7-MeV LEDA RFQ. The 52-magnet periodic lattice also includes ten beam position monitors (BPMs) evenly spaced in pairs of two. The BPMs provide a measure of the bunched beam current that exhibits nulls at different locations in the lattice. Model predictions of the locations of the nulls and the strength of the bunched beam current are made to determine what information this data can provide regarding the longitudinal beam emittance.