PC-based Acquisition System Research Articles

Data Formats and Analysis Codes–New Software for μSR

Abstract Originally investigated as a candidate common data format, NeXus was an easy choice when ISIS developed the present PC-based acquisition system. After over ten years of use there was a clear need to revisit the original instrument definition to improve utility, and this work is discussed in the paper. Using NeXus has opened up the possibility of accessing analysis codes developed by the wider scientific community. The application of Mantid for analysing muon data is particularly interesting, as this offers the muon community access to an analysis framework that is attracting broad international support. Recently, we have worked with the Mantid development team to program an interface for manipulating muon data that has confirmed the platform as an ideal tool for μSR analysis.

Allegria: a new interface to the ERD program

As a new PC-based acquisition system has been installed to replace the VAX-based system of the elastic recoil detection by time-of-flight (ERD-TOF) and gas-counter ERD setups at University of Montréal, a new analysis software has been developed. It includes a calculation of the energy calibration involving pulse height defects corrections for each element. It has been further improved to process a number of different ERD or Rutherford backscattering spectrometry (RBS) spectra in a single run and now incorporates stopping power calculations based on SRIM-2003 parameters. The application comes with a graphical interface that is used to extract mass separated spectra from event-list files. A second application allows the user to input the experimental parameters and prepares a command file that is passed to the ERD program. The latter iteratively converts the energy spectra into depth profiles for each mass. Resulting atomic fractions are normalized to one of the elements, typically the substrate or one of its components. Some examples of analysis for both TOF and gas counter ERD measurements are presented and discussed. The program and source code will be made available to the ion beam analysis community under GNU licensing conditions.

Accessing TJ-II data with remote procedure call

A new software, based on the de facto standard Open Network Computing Remote Procedure Call (ONC RPC) has been developed for TJ-II database access. This software solution replaces a previous development based on Berkeley sockets in which the client implementation had the drawback that was platform dependent. From the user point of view, the access to the TJ-II database can be done from codes running in the central server or from any other computer in the network in exactly the same way. From the development point of view, the ONC RPC tools allow to generate source code for the clients in an easy and flexible manner, thus reducing the work needed to maintain/upgrade the library for different platforms. The access to the database is managed by a concurrent server program, running on the central server, which implements each access routine as a service on the network. This allows controlling the accesses to the database. A client library has been developed to provide connection with the data server. This library implements a client routine per service, that interchanges parameters between client and server programs using External Data Representation. The client library has been installed in different UNIX and UNIX-like platforms, including ALPHA AXP/Digital UNIX, Sparc/SOLARIUS, INTEL/LINUX and CRAY/UNICOS and in Windows (NT/95/98) platforms. The support for Windows platforms allows autonomous PC-based acquisition systems to integrate experimental data into the data base. A basic in-house developed identification system is used to control client connections. An access policy has been defined in order to assign different permissions to different clients.

Integrated Data Acquisition and Instrument Control for Local and Remote Operation of Electron Microscopes Equipped With Imaging Detectors and Spectrometers

Abstract The continuing remarkable progress of computer technology is dramatically changing how electron optical instrumentation is being used. Instead of concentrating on taking just one spectrum or one image at a time, it now has become possible to design complete experiments aimed at solving the problems at hand more rapidly and more directly. We have designed a PC-based acquisition system that aims to innovate and simplify both TEM and STEM operation. The first advance this system represents is integrated data acquisition from all detectors commonly found on electron microscopes: TV and slow-scan CCD cameras, different flavors of STEM detectors, and EDX, CL, Auger and EELS spectrometers. The new system allows experiments combining microscope control with the acquisition capabilities of all these detectors. The second advance is the implementation of “live” processing. Most common processing tasks can be executed on-the-fly, even at video-rate acquisition speeds.

Flow cytometry signal processing and data acquisition with a personal computer using an RTI-800 multifunction A/D I/O board

The design and implementation of a data management system, consisting of a real-time data processing and a PC-based acquisition system, for measurement of flow cytometric data is described. The data processing system makes use of an erasable programmable logic device for implementation of dedicated control logic. The signal processing system is used for measuring the peak heights of 8 analog signals and simultaneous digital measurement of the time of flight. Four window discriminators are used for data selection and sorting applications. The data acquisition system is based on an MS-DOS PC with a slightly modified commerical A/D I/O board, which we used to measure 8 analog signals (12 bit A/D converted) and 32 bit digital information per event. Using an IBM compatible personal computer with an 8 MHz AT bus, the total system is capable of measuring about 10 000 events per second.

Computer-controlled scanning and acquisition system for atmospheric PIXE

A dedicated end station has been developed to allow convenient spatially-resolved trace element analysis in air using proton-induced X-ray emission. The system is able to scan over three-dimensional surfaces while maintaining a constant air gap through the use of an optical surface profiler. The scanning stage provides movement of several inches for all three axes, allowing the system to have a dedicated load position which is stepped away from the proton collimator. Specimens can be viewed directly at the computer display while in the specimen load position. This allows scan areas, lines and points to be specified directly on the video image prior to acquisition. The PC-based acquisition system is capable of acquiring an entire 1024-point spectrum at each of up to 10000 spatial points. Elemental maps can be generated quickly, since all data is stored in RAM.