Dear NEUTRINO-MC-SUPPORT,
I have a question about the Genie neutrino event generator Monte Carlo.
I hope this is the right place to post.
When I generate neutrino events with neutrino energies of 100 MeV or 1 GeV I have no problems.
But when I generate relatively high energy neutrino events with energies of around 10 ~ 100 GeV, I get error messages
such as the following (this particular example is from 100 GeV nue interaction with hydrogen nucleus):
************* Begin snippet *************
Error type 4 has occured after 4 PYEXEC calls:
(PYSTRF:) caught in infinite loop
Error type 4 has occured after 7 PYEXEC calls:
(PYSTRF:) caught in infinite loop
Error type 4 has occured after 9 PYEXEC calls:
(PYSTRF:) caught in infinite loop
Error type 4 has occured after 10 PYEXEC calls:
(PYSTRF:) caught in infinite loop
Error type 4 has occured after 12 PYEXEC calls:
(PYSTRF:) caught in infinite loop
Error type 4 has occured after 16 PYEXEC calls:
(PYSTRF:) caught in infinite loop
Error type 4 has occured after 17 PYEXEC calls:
(PYSTRF:) caught in infinite loop
Error type 4 has occured after 20 PYEXEC calls:
(PYSTRF:) caught in infinite loop
Error type 4 has occured after 26 PYEXEC calls:
(PYSTRF:) caught in infinite loop
Error type 4 has occured after 27 PYEXEC calls:
(PYSTRF:) caught in infinite loop
Error type 4 has occured after 33 PYEXEC calls:
(PYSTRF:) caught in infinite loop
Execution will be stopped after listing of last event!
Event listing (standard)
I particle/jet K(I,1) K(I,2) K(I,3) K(I,4) K(I,5) P(I,1) P(I,2) P(I,3) P(I,4) P(I,5)
1 u A 2 2 0 0 0 0.00000 0.00000 2.35699 2.37998 0.33000
2 uu_1 V 1 2203 0 0 0 0.00000 0.00000 -2.35699 2.47999 0.77133
sum charge: 2.00 sum momentum and inv. mass: 0.00000 0.00000 0.00000 4.85997 4.85997
PYSTOP called with code: 3
************** End snippet ***************
I read here
https://twiki.cern.ch/twiki/bin/view/LHCb/FAQ/GeneratorFAQ
that I can increase the number of allowed errors to a higher number so that Genie will continue to run even if
many errors are encountered.
The default number of allowed errors seems to be only ten.
I think I figured out that this is controlled by a parameter when compiling Pythia 6.4, namely the 22nd array element of
parameter called MSTU.
I changed this to a very high number, MSTU(22) = 100000, and recompiled Pythia 6.4 along with Genie to use the newly
recompiled Pythia 6.4.
Now Genie seems to complete the neutrino event generation run successfully although with many of the same type 4 error
messages (I think I get around 100 of them).
I'm not sure if this is the correct way to solve this problem.
Can some expert comment on what I have done, or suggest a better way to solve this problem?
Thank you for any help.
The version of my programs are Genie-2.8.2, Pythia-6.4.28.
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