In the hope that AMS will use geant4 much in the future, I began working with AMS software on geant4 flatform after talking with the AMS software manager. But whenever I talk with him, he said that geant4 is very slow. Geant3 is more than ten times faster than geant4, he said. He even said recently that geant4 may be eventually dropped from AMS software. It is really slow in the initialization in particular. CMS had devised to overcome this problem of initialization. If a program is slow, that will be a big problem for experiments which deal with large amount of data. I expected that geant4 will be faster in the long run. Could you tell me the prospect of this problem in the future? Geant4 will have excellent capability of complex data handling. Can you tell me the advantages of geant4 in the modern experiments? Cheers, Sangryul Ro
For example, BaBar had already demonstrated that G4 is at least as fast as G3. They had already produced 250 million events with Geant4. I don't understand by what reason you could say G4 is ten times(!) slower than G3.
