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The sum of the fractions is normalised - in the examples, fractions usually add up to 1 or to 100, but this is not mandatory.
[Each fraction is 0 by default.]
In either case, you can set the number of points with N-E or N-E/P (which are synonyms).
You have the choice between linear and logarithmic spacing of the points.
This format is useful if you wish, for instance, to study the dependence of the transverse diffusion on the magnetic field. This format should not be be used to generate tables for calculations on actual chambers.
It is advisable to choose the electric field range sufficiently large to cover all fields present in your chamber, rather than to rely on INTERPOLATIONS and EXTRAPOLATIONS.
[By default E ranges from 100 V/cm to 100000 V/cm in 20 logarithmically spaced steps.]
You can either ask Magboltz to compute the transport properties for a range of magnetic fields or for a single magnetic field.
You can set the number of points with N-B.
If you ask for only 1 magnetic field strength and only 1 angle between E and B, then Magboltz will generate a 1-dimensional table for which you have greater control over the INTERPOLATIONS and EXTRAPOLATIONS methods.
These parameters can not be used if there is no magnetic field.
[If the magnetic field can be determined to be constant or zero, then Magboltz by default only computes a table for the magnetic field that is present in the chamber. If the B field is not constant, but of known range, then Magboltz will by default be run for 6 magnetic fields ranging from the minimum field to the maximum field present in the chamber. In all other cases, it will compute tables for 0, 1, 2, 3, 4 and 5 T.]
You can either ask Magboltz to compute the transport properties for a range of angles between E and B or for a single angle between the 2 fields:
You can set the number of angles with N-ANGLES.
It is advisable to use this format, with ANGLE=90, if your chamber is such that E is always perpendicular to B.
It is bad practice to set ANGLE=0 in TPCs where E is parallel with B in the drift volume. Other orientations occur in the read-out chambers, and these orientations have impact on the resolution of the TPC.
If you ask for only 1 magnetic field strength and only 1 angle between E and B, then Magboltz will generate a 1-dimensional table for which you have greater control over the INTERPOLATIONS and EXTRAPOLATIONS methods.
These parameters can not be used if there is no magnetic field.
[Magboltz will, if B is non-zero, by default be asked to compute tables for an angle of 0, 30, 60 and 90 degrees between the E and B field.]
Keep in mind that Magboltz only computes F2 and F3 on request: to get F2 and F3 you need to request SECOND-ORDER-TERMS (or ORDERS 2) and for a reasonably accurate F3 you should specify ORDERS 3. Both are incompatible with the option ITERATE-ALPHA which enables a more precise computation of the Townsend coefficient.
F0 is plotted with representation FUNCTION-1, F1 as FUNCTION-2, F2 as FUNCTION-3 and F3 as FUNCTION-4.
This function is plotted with representation FUNCTION-1,
This option potentially generates a lot of output.
[The option is off by default.]
This option, which is not default, is provided for backwards compatibility only - Monte Carlo integration is currently believed to be superior.
Several anisotropic gasses can not be used when analytic integration is requested.
Additional information on:
[This is default.]
Additional information on:
This format only allows for mobilities that are constant or depend in a simple way on E/p. In the latter case, the argument of MOBILITY should be a function with EP as variable.
ADD provides a similar functionality, and can in addition be used if the mobility is available in tabular form.
The unit of mobility in Garfield is cm2/microsec.V.
[By default: no mobility.]
Formatted on 0100-08-24 at 22:37.