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     (See printing version)

    Garfield Version 7.02

    Rob Veenhof , CERN (EP) and GSI (Darmstadt, Germany)


    The main feature of Garfield version 7.02 is that it has an interface with the Magboltz 2 program. This should greatly improve the accuracy of calculations in which a magnetic field and diffusion are key factors.

    Garfield version 7 comes with a new gas section based on an interface with Magboltz 2 (see next article).

    CELL section:

    Maxwell generated field maps with rotational symmetry around an axis, such as r-phi maps, can now be read.

    MAGNETIC-FIELD section:

    The format of the COMPONENTS statement has been extended to allow for non-constant, parametrised or tabulated magnetic fields.

    OPTIMISATION section:

    The FORCES command plots, on request, a diagram which shows whether a wire is in stable or labile equilibrium.

    The CHANGE-VOLTAGES command now also works for planes and for the tube.

    FIELD section:

    No changes.

    GAS section:

    Garfield version 7 by default obtains electron transport data from Magboltz 2. An interface with the earlier version, Magboltz 1, has been kept. These 2 programs solve the same transport equations, but use different methods. Magboltz 2 is more stable numerically, and is reported to reach much higher accuracy especially for diffusion and deflection in a magnetic field.

    Garfield tries to take maximum advantage of Magboltz 2 by copying the full diffusion matrix, with correlation coefficients, and in a magnetic field, all 3 components of the drift velocity.

    As a consequence of the increased amount of gas data extracted from Magboltz, compact format gas datasets generated with Garfield version 6 can not be read with version 7.

    DRIFT section:

    In collaboration with Peter Cwetanski and Ulrich Moosbrugger, considerable progress has been made in the understanding of avalanche statistics on small scales. This has on the one hand resulted in the PROJECTED-PATH integration parameter, which to a large extent eliminates the dependence of the avalanche size on the Monte Carlo step size. On the other hand, a new procedure RND_MULTIPLICATION has been written which simulates the avalanche fluctuation over a fixed path, taking attachment and multiplication into account.

    SIGNAL section:

    Multiple weighting field maps computed by finite element programs are now accepted. This should simplify the computation of response functions of cathodes segmented in strips and pads.


    A limited amount of user control of the layout of Cartesian plots is provided through the LAYOUT graphics command.

    Environment variables are now expanded in metafile names.

    Histograms, Matrices, Formulae and Calls:

    As usual, many procedures have been added. Of particular importance are a the RND_MULTIPLICATION mentioned before, and random number generators according to functions and histograms (RND_FUNCTION and RND_HISTOGRAM). The function random number generator is based on the FUNLUX routine from the CERN program library.

    Garbage collect for matrix assignments in loops has been improved.

    Datasets and input / output:

    No changes.

    Compilation, batch:

    No changes.


    Currently, the most accurate information can be found in the help pages and the description of the command line.
    About the author(s): Rob Veenhof is a physicist currently working on the design of the read-out chambers of the Alice and Harp TPCs.

    For matters related to this article please contact the author.

    Vol. XXXV, issue no 1

    Last Updated on Thu Apr 13 20:29:10 GMT+04:30 2000.
    Copyright © CERN 2000 -- European Organization for Nuclear Research