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Garfield Version 5.25 - Overview of Modifications

  Rob Veenhof, Saclay

OPTIMISATION section: The routines computing the forces acting on the wire have been corrected after it had been found that mirror charges were in a few cases not properly taken into account (Pawel Majewski). An option has been added to compute the shape of the wire, which can be useful if the force acting on the wire depends in a non-trivial way on the sag.

A potential for a 3-dimensional point charge inside a round tube with a wire at its centre is being introduced. The potential is zero both on the tube wall and on the wire.

GAS section: Various keywords on the MAGBOLTZ command have been modified:

 ITERATE-ALPHA  has been added
 SWITCH         has been added

The latter option is recommended - for low field strengths, higher order terms are taken into account, for higher field strengths, the Townsend coefficients are privileged.

The gas identifier generated automatically by the MAGBOLTZ command rounded the fractions to the nearest integer percentage. This has been changed.

The graph of the Townsend and attachment coefficients made in response to the GAS-PLOT option, have been combined into a single plot.

PROGRESS-PRINT now has an effect on MIX and MAGBOLTZ.

DRIFT section: Track preparation and interpolation has been made 3-dimensional. Track preparation is now also available from the signal section. The interpolation routine has been made 15 % faster.

SIGNAL section: Most of the signal section has been rewritten, both to improve the accuracy and to permit more flexible simulation.

New are the following features:

calculation of the electron pulse by tracing the avalanche over the electron drift line, also cross-talk due to electrons can be computed;
the ion tail calculation now takes the following into account:
the distribution in space of ion production in the avalanche
the current induced by ions depends on the angle in which they drift;

the signals can be convoluted with the transfer function of the electronics;
noise can be added to the signals;
a procedure call has returns threshold crossing times;
the z-dependence of the track is taken into account.

Various changes have been made to existing commands:

the REPEAT option has disappeared since DO loops offer more functionality;
the SIGNAL-PLOT option has disappeared, and been replaced by a command, PLOT-SIGNAL, that immediately plots the signals; it accepts a series of arguments by which one can selectively plot parts of the signals;
WRITE-SIGNAL now writes the signals that are available at the moment the command is issued, rather than during the computation of the signal. Arguments have been added to write out pieces of the signals.

The idea is to provide building blocks for making instructions like ARRIVAL based on signals. Since the needs of the users vary substantially, it does not seem meaningful to provide a complete instruction.

graphics: The WAIT-AFTER-PLOT is now respected when linking with HIGZ.

formulas: Clean-up of global variable re-usage.

A new data type, the matrix, has been added. With it comes a series of procedures.

Users are reminded that curly brackets should only be used to substitute expressions in terms of global variables into normal instructions. They should not be used after IF, DO, GLOBAL, CALL or PARSE (the control statements).

datasets and input / output: For Unix systems, a leading tilde and the environment variables are substituted in file names.

global options: The RNDM_initialisation option used to result in calls to RNDM only. Since this random number generator is being replaced by calls to RANLUX, also RANLUX is called a number of times now if the option has been selected.

compilation: The SP2 version is increasingly making use of the ESSL library, which is substantially faster than the equivalent CERN library routines (factors of order 25 are usual).

front-end programs and EXEC files

The INPUT_LISTING option has been added as command line argument.


The Garfield manual and a set of examples can be found on WWW via

next up previous
Next: Program Library Up: Application Software & Databases Previous: CMZ to be Frozen

Michel Goossens
CN Division
Tel. 3363
Thu May 30 20:08:07 METDST 1996