Introduction

Coincidence measurements are a powerful tool in physics for observing complex phenomena. The close time relation of two or more parameters assures that such an event results from a single physical process.

The simultaneous acquisition of two or more physical parameters using ADC’s or TDC’s result in set of numbers that characterize a a specific physical process in detail. This set of numbers can be looked at as a n-dimensional vector. The histograming (accumulation) of a large number of these vectors result in a multidimensional spectrum that is usually stored in the memory of a PC.

As n-dimensional spectra can not be visualized on a PC-monitor and are very difficult to imagine by the human mind it is necessary to compute projections in a single or two dimensions for easy viewing on a computer monitor.

Conditions are usually applied on the remaining parameters. Analysis software is available to meet typical requirements of the experimenter.
An alternative storage facility is in "list-mode" – this means the capability of the system to store the incoming events in the order of arrival in a mass storage devices like hard disks (HDD).

The advantage of a data storage in list mode is that one set of experiment data can be analyzed on and on using the same data with varying analysis parameters. We call this Replay – an efficient way to save the user from repeating the experiment many times if the analysis parameters are not set to an optimum. If properly stored the data saved in list mode can be analyzed even years later using different analysis algorithms without the need to repeat the experiment.

A few examples of the numerous applications where our multiparameter system is used are:

Dynamic Analysis PIXE Imaging
Watching chips (680 kB) 
Microprobe (490 kB) 
X-ray Microprobe and Micro-Tomography (640 kB) 
Micro-PIXE analysis of an Egyptian Papyrus (1.8 MB) 
Multi-Dimensional Ion-Photon Nuclear Microprobe System for Induced Ion-Effect
Analysis (2.6 MB) 
Particle Identification (330 kB) 
ERDA: Elastic Recoil Detection Analysis (340 kB) 
Small angle scattering of X rays (SAXS) (450 kB) 
Ultra Low Background Systems (590 kB) 
High Voltage Partial Discharge in Power Generators and Power Transformers (90 kB) 
Positron Annihilation (506 kB) 
The Ion-Electron Emission Microscope (169 kB) NIM B 158(1999)6

Short descriptions of the MPA-3 multiparameter system:

Hardware Description (1.7 Mb) 
Software Description (310 kB) 
Screen presentation including 2 MPEG Videos (4 Mb)