This keyword need not be specified if the cell is already established to be in Cartesian coordinates, for instance if a plane at constant x has already been entered. This keyword is not valid if the cell is already established to be in polar or in tube coordinates.
When Cartesian coordinates are used, you may enter planes at constant x and at constant y. Also both x and y periodicities are permitted.
[If no coordinate system has yet been established when ROWS is entered, then Cartesian coordinates are assumed by default.]
When the wires are listed in polar coordinates, the planes have to be entered in polar coordinates too. That is, the planes can be at constant r or at constant \φ.
Periodicity in \φ is permitted, but radial periodicity isn't.
These coordinates are transformed to an internal coordinates system which is a conformal map of a Cartesian system - but all frequently used instructions transform these internal coordinates back to polar coordinates when displaying the results.
This keyword need not be specified if the cell is already established to be in polar coordinates, for instance if a \φ periodicity has already been entered. This keyword is not valid if the cell is already established to be in Cartesian coordinates or in tube coordinates.
[If no coordinate system has been established yet when the ROWS command is entered, then Cartesian coordinates will be assumed by default.]
The tube itself and the \φ periodicity, if any, is specified in polar coordinates, but the wires are listed in Cartesian coordinates.
Like for polar coordinates, a coordinate transformation is applied to the wire location but the internal coordinates never appear on output.
This keyword need not be specified if the cell is already established to be in tube coordinates because a TUBE statement has already been entered. This keyword is not valid if the cell is already established to be in Cartesian or polar coordinates.
[If no coordinate system has been established yet when the ROWS command is entered, then Cartesian coordinates will be assumed by default.]
These labels are used by the SELECT statements to single out (groups of) wires from which particles should drift, for which arrival time distributions are to be computed, on which signals can be recorded, etc.
[Initially, all wires with a label of S are selected for such treatment.]
Each wire in such a row will have the same status as if it were entered on a separate line. Entering wires in the form of rows has no incidence on the choice of potential_function used for the chamber.
The number of wires may be a symbolic expression in terms of DEFINEd variables but you may, of course, not use the loop-variable I.
[Default: 1, i.e. a single wire].
Since the electric fields are currently computed in the thin wire approximation, i.e. neglecting dipole and other higher order terms, care has to be taken that the wire diameters are small compared to the inter-wire distances. One can use the MULTIPOLE-MOMENTS instruction to investigate the need for higher order terms to describe the field around the wire.
Consider using the DIPOLE-TERMS in case dipole terms are thought to be important.
This may be a symbolic expression in terms of DEFINEd variables and you may use the loop-variable I in the expression if you wish.
[Default: 0.01\ cm, i.e. 100\ \μm].
If the cell is described in Cartesian or Tube coordinates, then (x,y) coordinates should be used for the wire location. The wire coordinates should be given in (r,\φ) format for Polar cells.
This may be a symbolic expression in terms of DEFINEd variables and you may use the loop-variable I to construct symbolic expressions for the locations of the wires in the row. For instance, for a series of wires with coordinates 1, 2, 3 and 4 you could enter the expression
1+I
[Default: 0\ cm.]
If the cell is described in Cartesian or Tube coordinates, then (x,y) coordinates should be used for the wire location. The wire coordinates should be given in (r,\φ) format for Polar cells.
This may be a symbolic expression in terms of DEFINEd variables and you may use the loop-variable I to construct symbolic expressions for the locations of the wires in the row. For instance, for a series of wires with coordinates 1, 4, 9 and 16 you could enter the expression
(1+I)^2
[Default: 0\ cm, \φ should be in degrees.]
This may be a symbolic expression in terms of DEFINEd variables and you may use the loop-variable I to construct symbolic expressions for the locations of the wires in the row. For instance, for a series of wires with potentials 1000, 1000, 2000 and 2000, you could enter the expression
1000+entier(i/2)*1000
[Default: 0\ cm.]
Used by the FORCES command to estimate the wire displacement under gravitational and electrostatic forces.
This may be a symbolic expression in terms of DEFINEd variables and you may use the loop-variable I to construct symbolic expressions.
[Default: 50\ grams.]
Used by the FORCES command to estimate the wire displacement under gravitational and electrostatic forces.
This may be a symbolic expression in terms of DEFINEd variables and you may use the loop-variable I to construct symbolic expressions.
Note that the length of the wires has no impact on the fields in the chamber. Fields in chambers that are made up of wires and planes are truly 2-dimensional and are identical at all z, irrespective of the length of the wires. If you're interested in the end-effects of finite length wires, then you should use a finite element field map.
[Default: 100\ cm.]
Used by the FORCES command to estimate the wire displacement under gravitational and electrostatic forces. Not relevant if the wires are vertical.
For copper-beryllium wires, one can also enter CU-BE and for gold plated tungsten one can type TUNGSTEN or W.
This may be a symbolic expression in terms of DEFINEd variables and you may use the loop-variable I to construct symbolic expressions.
[Default: 19.3\ g/cm\³, i.e. 20\ \μm gold-plated tungsten wire]
This feature is less powerful than the method using the loop-variable and the increments have therefore been suppressed as of version\ 5.
This modification is not backwards compatible - input files prepared for Garfield\ 4 and earlier need to be modified.
This variable may be used for the diameter, the position, the potential, the stretching weight and the length of the wire.
The loop-variables can be used to construct non-standard electrode shapes using wires. Some examples are shown in the description of the wire position and voltage.
Note that the loop variable is not a Global variable: while substitution of expressions in terms of global variables has to be requested explicitly by means of curly brackets, expressions in terms of DEFINEd variables and the loop variable are automatically evaluated. Curly brackets should not be used with such variables.
Formatted on 21/01/18 at 16:55.