Problem 43

Summary: transportation of particle in large volume in the field
Product: Geant4 Reporter: liuht
Component: processes/transportationAssignee: John Apostolakis <John.Apostolakis>
Status: RESOLVED WORKSFORME    
Severity: normal    
Priority: P2    
Version: 1.0   
Hardware: PC   
OS: Linux   

Description liuht 1999-12-12 04:36:01 CET 
I am working on AMS analysis, I use Geant4 to simulate the  +  cosmic ray
behaviar around the earth. It seems it can not trace out when I use the default
driver. I find it is beacause it calculate the peceision as
fDefault_Delta_Intersection_val/(the distance for next reaction); It will be
extreamly small when I want to trace the particle in the space and the particle
can hardly move. Which driver should I choose the cosmic study?
Comment 1 John Apostolakis 2000-01-24 11:13:59 CET 
In volumes where very large steps can happen,  we recommend that the logical
volume's "user limits" are used to limit the length of a single step (using the
maximum step length.)

Also the accuracy that is utilised can be set using the following method:

class G4PropagatorInField {
   ...
   // Sets both accuracies,
   //    maintaining a particular ratio Delta Interaction / OneStep )
   void    SetAccuraciesWithDeltaOneStep(G4double deltaOneStep);