Simulation Tutorials and How-Tos

How To Produce Your Own Simulated BaBar Events

For SP4, simulated events were produced using the three-stage procedure of Bogus, SimApp and Bear, in which intermediate as well as fully reconstructed information was persisted in the database. In order to reduce database transactions and increase execution speed, SP5 will employ a one-stage process, MOOSE, in which only the reconstructed information is persisted. The three-stage process is still very useful, however, in debugging the simulation. A detailed recipe for running both of these procedures is given in the BaBar workbook page. An example set-up session is also provided.

How to Produce Views of the Detector

This example uses OpenGL to produce views of the BaBar detector within Bogus. To produce views of single subsystems, all other subsystems must be removed from the Bogus geometry.

1. First set the following environment variables:
   • setenv INTERACTIVE 1 -- brings up the Idle> prompt in Bogus
   • setenv RUNNUM 250000 -- set the run number
   • setenv NEVENT 1 -- only need one event for displaying detector elements
   • setenv CONDALIAS Sep2001 -- to get database conditions
   • setenv CONFIGALIAS $CONDALIAS-Cfg -- to get configurations
2. Now run BgsApp, for example:

        BgsApp ../BgsApp/BgsUserExampleEvtGen.tcl
        

   At the "Idle" prompt type
   

        /vis/scene/create
        /vis/sceneHandler/create OGLSX
        /vis/viewer/create
        

   a view of the detector should now appear
   
   
3. to get a fresh view

        /vis/viewer/refresh
        

   
   
   
4. to look at the detector from different angles:

        /vis/viewer/viewpointThetaPhi theta phi
        

   where theta and phi are in degrees
   
   
5. to magnify (or de-magnify) the view:

        /vis/viewer/zoomTo scale-factor
        

   where scale-factor musrt be greater than one to expand, and smaller to contract.
   
   
6. to produce a cross sectional view:

        /vis/viewer/set/sectionPlane on x0 y0 z0 cm vx vy vz
        

   where (x0, y0, z0) is a point through which the cut plane passes and (vx, vy, vz) is the normal to the plane. As an example, choose (x0, y0, z0) to be (0,0,0) and (vx, vy, vz) to be (-0.95, 0.31, 0.0). The cross sectional view can be turned off by

        /vis/viewer/set/sectionPlane off
        

   
   
   
7. You can choose between surface-style drawings or wireframes by

        /vis/viewer/set/style s
        

   or

        /vis/viewer/set/style w
       

   
   
   
8. Many more options are available by typing help at the Idle> prompt.
9. To finish, type exit at the Idle> prompt.