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Manuscript Title: Measurement and three dimensional reconstruction of particle tracks in emulsion chambers.
Authors: S. Persson
Program title: MENU-EMU, VERSION LUND/10/88
Catalogue identifier: ABJI_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 55(1989)103
Programming language: Pascal.
Operating system: DOS 3.3.
RAM: 75K words
Word size: 16
Peripherals: graph plotter.
Keywords: Particle physics, Elementary, Detector control, High-energy emulsion Collisions, High-multiplicity events, New measuring station, Emulsion chambers, Ibm compatible/xt with A 8087 math-processor, Microscope, A coordinate digitizing Pad, Menu-driven software Package, Turbo pascal.
Classification: 11.8.

Nature of problem:
In high energy nucleus-nucleus collisions the particle production is very high and the emission angles are small. It is therefore difficult to make accurate measurements of all the emission angles with the conventional emulsion techiques. We have designed a special emulsion technique, for fast mesurements, using emulsion layers placed perpendicular to the beam direction during exposure. This technique needs a special designed measuring station combined with new computer programs.

Solution method:
The events are measured in all emulsion layers in the chamber, reconstructed using a full three dimensional least squares fit and afterwards visually inspected to check that all tracks are correctly measured. The software package forces the operator to make the measurement in a predefined way which decreases the possibility to make fatal errors. This setup can handle very large multiplicities at least up to around 1000 produced particles.

The only known restriction obtained so far is the reconstruction program, which in this version only can handle 750 produced particles. For larger multiplicities more memory is needed and then one can either use dynamic variables more efficient or move the reconstruction procedure to a larger computer. Other applications The software package is written for a semi-automatic measuring station where a coordinate digitizing pad is used to read the coordinates of each track in the emulsion layers. From this information the programs calculate different physical quantities. The programs can be rewritten to handle other types of coordinate devices, like CCD camera pictures. Then just an adjustment to the new measuring setup has to be done in the programs. The software package can also be used in an automatic measuring station. In this case the measurement program must be able to to find the coordinates of all points in each layer, and an algorithm which connects all points belonging to each track must be included.