QUICK FACTS
The Van de Graaf group of the Institute for Reference Materials
and Measurements (IRMM) in Geel, Belgium, works in the field of
nuclear physics, investigating properties and interactions of materials
using a 7-megavolt particle accelerator. This process generates
enormous amounts of data in the form of meter-long lists of values.
The Institute used PV-WAVE to develop a tailor-made software solution
that produces meaningful information from the data.
THE PROBLEM
One of the most important resources in nuclear and high-energy physics
is the particle accelerator that is used to study the various interactions
and therefore the structure of subatomic particles. Particle accelerators
are used in medicine for radiotherapy, in engineering for nondestructive
materials testing and in chemistry for the polymerization of monomers.
The Van de Graaf group at the IRMM uses its accelerator for materials
testing and research into new materials. Experiments carried out
here provide different forms of data. Both spectral analysis for
the various materials (from which the data are output in a cumulated
form) and individual data, recorded by the various detectors, are
collected during the course of the experiments. In such cases, entire
"data deserts" arise in the form of lists, in which even
accomplished researchers can lose their way.
To manage and evaluate these masses of data, which are recorded
by various measurement devices and passed on to data-acquisition
software, the engineers at IRMM decided to provide a data-processing
system for the experiments in a usable form -- developing software
that makes data analysis and visualization possible.
The requirements for this system, code named LISA (Listed and Spectral
Data Analysis), were to:
Furthermore, the program needed to be capable of communicating
with the data acquisition module of the German company, Delta of
Hamburg.
The goal was to allow researchers to solve the standard problems
such as spectrum investigations, graphical representation, printing
results and setting parameters and to define functions that do not
follow these standard patterns. This flexibility made it necessary
for LISA to recognize the different data forms, i.e., the cumulated
spectral data and the list-mode data, which represent a sequence
of events in the course of the experiment. Numerical values here
correspond to an event such as a collision, values that are associated
with each event in the experiment and result from the conversion
of the analog signals from detectors.
THE SOLUTION
The developers at IRMM chose the PV-WAVE software from Visual Numerics
as the basic software for the development of a system that meets
their requirements. PV-WAVE is a software package for interactive
analysis of scientific data. It contains both a programming environment
and GUI tools for graphical presentation and analysis. It is capable
of providing a rapid representation of large multidimensional volumes
of data, combining and analyzing this data interactively.
The PV-WAVE core functions can be expanded by adding new procedures.
The program itself already provides many of the desired functions
for presentation, output and analysis, but some data 
processing,
which must be carried out while the experiment is in progress (real
time) on an event-by-event basis, were better catered for by the
inclusion of analysis modules (known as processors) written in C.
Communication between standard applications and the C processors
is carried out by PV-WAVE, so that the user is unaware of the presence
of this additional module.
The experiments may last for days or even weeks, and so the user
often needs to be able to change calibration parameters during the
run. This was achieved by the generation of parameter files that
are accessed by the command files, allowing LISA to process massive
quantities of data from a large experiment, with varied settings
to compensate for drift.
Regardless of the analog/digital converter (ADC) used, more than
10,000 events can be processed every second; an event consists of
up to eight ADC words (16-bit) and corresponds to a data rate of
150 kilobytes per second.
RETURN ON INVESTMENT
LISA currently runs in an Ethernet LAN on a Sun® (SparcStationTM)
workstation cluster. Also integrated into the network are PCs (with
X Terminal emulation), tape drives, external hard disks and plotters.
The program is operated in a graphical user interface (GUI) mode
via the input of keyboard commands and via the pull-down menus.
The program package was implemented under X Windows and UNIX®,
using Visual Numerics' PV-WAVE with some analysis modules programmed
in C. All data are managed from the LISA framework by assigning
UNIX shell commands. LISA is therefore a powerful tool for on-line
and off-line data analysis that, because of the portability of PV-WAVE,
can also be used on other UNIX systems. With minor modifications
to the UNIX calls, it can even be used on Digital® equipment
VMS® machines.
WORLD CLASS PRODUCTS, SERVICES,
AND SUPPORT
Visual Numerics has provided technical software
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The company's software products help users understand complex data
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Visual Numerics offers two product lines: the IMSL® Numerical
Libraries for powerful mathematical and statistical analysis and
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