Call: DRIFT_MICROSCOPIC_ELECTRON

options

A String which may contain one or more of the following options and their negated version (prefix with NO):

MARK-ATTACHMENT: Marks the location where attachment occurs with representation ATTACHMENT. The electron will as a rule stop at these locations.
MARK-ELASTIC: Marks the locations of elastic interactions, using ELASTIC. This is nearly always the most common type of collision.
MARK-EXCITATION: Marks the locations of inelastic collisions where an excited state is produced. The point will be drawn using EXCITATION.
MARK-INELASTIC: Marks the locations of inelastic but non-exciting interactions. The position will be marked using INELASTIC.
MARK-IONISATION: Marks the locations where ionisations occur using IONISATION.
MARK-SUPER-ELASTIC: Marks the locations of super-elastic interactions using SUPER-ELASTIC.
PRINT: Switches on Magboltz printing. Use the DEBUG option to obtain details for each step.

Note: switching on any of the MARK options presumes that you have already opened a graphics window suitable for plotting the drift-line. Example:

 Call plot_drift_area
 Call new_track
 Do
    Call get_cluster(x,y,z,n,e,done)
    If done Then Leave
    Call drift_microscopic(x, y, z, status, time, ...
       `mark-ion  mark-att`, ...
       5.0, 0.1, 0,0,0, histe)
    Say "Status = {status}, Drift time = {time} microsec"
    Call plot_drift_line
 Enddo
 Call plot_track
 Call plot_end

In this example, all electrons generated along a track are traced and plotted, marking locations where ionisation and attachment occurs.

e_maximum

Maximum kinetic energy in eV the electron is expected to reach during the trajectory.

The calculation of the electron trajectory is aborted with status "Energy exceeds E_maximum" if at any point the electron energy exceeds this value.

The trajectory will be inaccurate if the maximum energy is chosen too large.

The simplest way to find suitable values for this parameter is running MAGBOLTZ with the PLOT-DISTRIBUTION-FUNCTIONS option switched on. Beware that e_maximum must be suitable over the entire drift path of the electron, which may include a high field region in the vicinity of an anode.

[Default: 5 eV]

e_start

Kinetic energy in eV of the electron at the start of the trajectory.

This energy must be strictly positive (non-zero) and less than e_maximum.

[Default: 2\ % of e_maximum.]

dir

Direction vector of the initial velocity of the electron. The initial direction has, in most gaseous detectors, little impact.

The norm of the initial velocity is taken from e_start, not from the direction vector. The normalisation is arbitrary.

All three components must be specified. If all 3\ components of the direction vector are zero, then an isotropic random vector will be generated.

[A random direction is assumed if no direction is specified.]

distribution

On return an Histogram which contains the electron energy distribution sampled just prior to every interaction with the gas molecules.

If this argument is on entry an existing histogram, then new entries will be added to it. This can be used to force a scale and also to accumulate statistics across multiple calls.

If this argument is of another type on entry, then the current value will be deleted and a new histogram will be booked with 100\ bins and ranging from 0 to e_maximum.

rates

This procedure returns the detailed counts of the interactions in the form of a 1-dimensional Matrix.

The cross sections present in the vector vary with e_maximum since Magboltz eliminates, for reasons of efficiency, negligibly small cross section terms.

The various terms can be identified with the help of the CROSS_SECTION_IDENTIFIER procedure:

Call drift_microscopic(x, y, z, status, time, ``, ...
   100.0, 4.0, 0,0,0, histe, vec)
For i From 1 To size(vec) Do
   Call cross_section_identifier(i, level, type)
   Say "Level {i} = {level}, count = {number(vec[i])}, type = {type}"
Enddo

Go to the top level, to Call, to DRIFT_MICROSCOPIC_ELECTRON, to the topic index, to the table of contents, or to the full text.

Formatted on 21/01/18 at 16:55.