|Message: Re: Different perfomance on Linux and Windows||Not Logged In (login)|
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------------------------------------ What problem you may have: some protons reflected back, so if beam direction is along Z axis from Z=0, Z-distribution of end points will have a peak around the range R(E) and the tail with -R(Z)< Z < R(Z). If you have a small statistic, the tail may not be seen at all, suddenly 1 event has random end point Z in this interval and damage the mean value... ------------------------------------
I have tried to eliminate backscattered protons from the calculations, but the results are not very much changed. With 4.8.1.p01 (also with 4.8.2 that I currently installed) the number of backscattered protons is somewhat 1-2 per 1000 incident projectiles. In case of 4.8.0.p01 the number is hardly one per 5000 or even higher. But in any case, I notice that the stopping of protons in medium is more reliably predicted with 4.8.0.p01 rather than with newer releases. There might've been an option that I am doing something wrong, but a) since you mentioned that my ways of calculations are correct and b) the same source code on different releases produces different results for the same process, there's nothing much left but to attribute the differences to the release itself. 4.8.0.p01 provides more reliable outcome for stopping than the newer releases, since the results are pretty similar with those obtained in SRIM. Some few % of differences can be blamed on low statistics and slight differences in stopping forces. I have tested only Tantalum material. The material is defined "brutally" inside the code via:
G4Material* Ta = new G4Material("Tantalum", z= 73, a= 180.9479*g/mole, density= 16.69*g/cm3);
Some differences in the density might be present in different data sets.
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