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Manuscript Title: POP: an interactive charged particle transport system design tool.
Authors: T.P. Morrison
Program title: POP
Catalogue identifier: ACGK_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 69(1992)477
Programming language: Fortran.
Operating system: VMS, SUN OS.
RAM: 35K words
Word size: 16
Peripherals: graph plotter.
Keywords: Elementary, Particle physics, Charged particle beam transport, Magnets (dipole, Quadrupole, sextupole), Wien filters, Electrostatic Accelerator elements, Achromatic matrix Technique, Interactive graphics, Spectrometer design, FORTRAN, GKS.
Classification: 11.10.

Nature of problem:
The design of particle accelerators, analysers and focusing devices requires calculation of the paths of moving charged particles through such systems. This must be done for suitable ranges of geometric and kinematic phase space such as those found emanating from ion sources or reaction spots on samples or targets in many types of experimental measurement.

Solution method:
Within the limits of a lumped system, POP calculates a small group of such trajectories using chromatically accurate matrix techniques which are geometrically truncated to 2nd order.

The results do not give path curvature inside electromagnetic field regions. POP is presently limited to a maximum of 50 elements per system. It plots 9 rays at the centres and vertices of each plane of the system for each value of kinematic parameters.

Unusual features:
The trajectories and a schematic representation of the system are displayed at a graphics terminal and can be usefully printed on a variety of devices. The design can be saved at any stage to a named file in a format which can be reused later. The format can be used by other software also.

Running time:
Speed is limited by graphics terminal system used. A 50 element system takes about 45 seconds to plot to a VT340 device via a 9600 baud connection. A modern graphics workstation can display the same system in about 1 second. Faster terminals are perferred to allow exploitation of POP's ability to interactively alter system parameters like lengths and field strengths which is of great use in design and visualisation of charged particle transport systems.