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Garfield Version 6.19

  Rob Veenhof, IPN Orsay and NIKHEF

The main new feature of this version is the extension of the interface with the Maxwell finite element program, both for 2-dimensional and for 3-dimensional configurations.

CELL section

An interface for Maxwell 3D files has been added, and the interface for 2D files has been extended to include also the fields needed to compute signals on conductors present in Maxwell models. The very fruitful collaboration with Salvador Iranzo is gratefully acknowledged.


No changes.


A background field and potential, expressed in analytic form, can be added with the BACKGROUND-FIELD command.

FIELD section

A command, VIEWING-PLANE, has been added for making plots of 2D cuts through 3D field maps,

The axis labeling for PLOT SURFACE in HIGZ compilations has been corrected (the x and y axis labels were interchanged).

GAS section

The cross section parametrisations for Argon in Magboltz have been replaced. The new cross sections are in better agreement with the Townsend data of Abdullah et al. and of Davies and Milnee. The transport properties at low and moderate fields do not change significantly.

An instruction, called ADD, has been added which enables one to add/replace elements to/of the gas tables.

Comparison of Magboltz calculations and measurements has shown that the diffusions estimates returned so far by the interface are less accurate than other estimates available in Magboltz. After consultation with the Steve Biagi, the default set of diffusion coefficients has been modified -- the old set can still be obtained via options described in the help file ( The transverse diffusion is particularly affected by this modification.

We have also observed that the Townsend coefficients computed with the ITERATE-ALPHA and SWITCH options, although in principle more accurate, agree less well with the data for several gasses than those computed with the NOITERATE-ALPHA option.

The AXES command has been extended and has been renamed PLOT-OPTIONS.

DRIFT section

Options have been added to the CLUSTERING-HISTOGRAMS command to enable user control of the histogram binning.

SIGNAL section

Routines have been added to compute signals in polygonal tubes.

A numerical inaccuracy has been corrected in cells with 4 equipotential planes. Signals were accurate close to the wires, but inaccurate close to the planes.

Signals can now be computed on conductors for which a weighting field has been entered via the FIELD-MAP command in the cell section.

The units of signals written out to a dataset are now under user control.


Vector plots are now drawn with true vectors rather than line elements. The top angle of the vectors can be modified with the ARROW-TOP-ANGLE graphics command.

Tickmarks were absent in the first decade of log scaled axes. This has been corrected now.

Two new models of markers have been added: TRIANGLE and HEXAGON, the triangles can have 4 orientations.

Histograms, Matrices, Formulae and Calls

Along with the total number of arithmetic errors, details of their nature are now printed. An option IGNORE-UNDERFLOW has been added to the algebra subsection to set exponential underflows equal to zero, without further warnings.

The argument list of procedure GET_CLUSTER has been modified to include the energy deposited in the cluster.

A mistake in the return arguments of FIT_FUNCTION has been corrected -- the correct results were displayed, but they were not stored in the proper global variables.

Procedures have been added for the conversion between matrices and histograms, MATRIX_TO_HISTOGRAM and HISTOGRAM_TO_MATRIX.

A new procedure AVALANCHE has been added. This procedure is an extension of the Monte Carlo drift line integration procedures in which the generation and absorption of electrons and ions is simulated using the Townsend and attachment coefficients. Secondary electrons and ions are traced, and can induce further avalanches. Space charge is currently not taken into account.

Datasets and input / output

Most WRITE instructions now check whether the dataset to be written to already contains a member of the same type and with the same name. A set of global options has been added to control the action to be taken if such a member exists.

Global options

See datasets.


No changes.


Currently, the most accurate description of the program can be found in the on-line help (, the printed manual is not available at the moment, for lack of SGML at CERN. A set of examples can be found on WWW (

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Next: Questions and Answers from the UCO Up: cnl229.html Previous: Cernlib on Windows NT/95