README.test1       DCW Oct 8, 1998

The first test involves the use of a particle generator called "SprayGun",
controlled interactively, and an event display.

I have found the VRML display to be particularly useful for this.
A VRML display can be selected by executing the script "draw3d.script".
See GEANT4 documentation for more information on setting up a VRML display.

For this test, the spray gun as a particle generator should be selected
(this is by default):

/fred/gun SPRAY

In addition, the "NORMAL" drawing mode should be selected (this is by default):

/fred/draw NORMAL

Before run initialize, a volume should be specified. See README.volumes
for details.

Fred displays the event at the end of each event (as activated by command
/run/beamOn). Drawn in red is the test volume and in green are trajectories
of geantinos. For every exit intersection of the trajectory with the
test volume, a white sphere is drawn. For every entry intersection, a
blue sphere is drawn.

The spray gun creates geantinos emitted from a central point along
x, y, and z angles in increments of 45 degrees. The position of the central
point is controlled by the command:

/sprayGun/position <x> <y> <z> [<units>]

The angles are controlled by the commands:

/sprayGun/xSpray  <xmask>
/sprayGun/ySpray  <ymask>
/sprayGun/zSpray  <zmask>

Each mask has the following meaning:
    Bit 0: add tracks with a positive momentum with respect to this axis
    Bit 1: add tracks with zero momentum with respect to this axis
    Bit 2: add tracks with a negative momentum with respect to this axis
By default, xmask=7, ymask=7, and zmask=2, which produces 8 geantinos
in the x/y plane at angles of 45 degree increments with respect to the x 
or y axes.

To test a volume: interactively place the sprayGun central point along
difficult positions around or in the volume, and visually inspect the
results for errors. A knowledge of the difficulties of correctly
implementing volumes is important to select challenging positions for
tests.

If an error is found, the xmask, ymask, and zmask values can be specified
to produce only the one track that causes the error. This can greatly
simplify the task of debugging.

A example debugging session is included below:

/vis/open VRML1
/vis~/create_view/new_graphics_system VRML1
/vis~/camera/zoom 16
/tracking/storeTrajectory 1	
/vis/draw/current
# select test volume BOX
/fred/volume BOX
# initialize
/run/initialize
# select VRML display
/control/execute draw3d.script
# display an event 
/run/beamOn 1
# change spray gun to send trajectories at +/- z
/sprayGun/zSpray 7
# change position of particle sources
/sprayGun/position 1.0 1.0 0.0 m
# display results
/run/beamOn 1