From: John Clem (clem@bartol.udel.edu)
Date: Wed Jun 23 2004 - 16:22:15 CEST
Dear All,
I have a couple of questions:
1) I'm directing a beam of 20GeV protons vertically into the atmosphere
and recording the neutrons and muons that reach sea-level. LAM-BIAS is set
at -0.5 for inelastic biasing. To determine the effectiveness of LAM-BIAS,
the number of weighted neutrons above 20MeV are counted. Each run has 1000
20GeV protons...
Run# Number of Neutrons >20MeV
1 74.4391111
2 97.5083734
3 78.7172711
4 83.6408111
5 65.2695326
6 79.2154181
Ave 79.79842
RMS 9.744451
Muons >500MeV were also collected at Sea-Level
1 201.015869
2 214.285889
3 212.272003
4 204.647949
5 193.411865
6 189.782959
Ave 202.56942
RMS 8.995406
The run to run variation seems higher than expected. In the case for
neutrons this suggest 600000 20GeV Protons at LAM-BIAS = -0.5 would be
needed for a ~1% statistical error. I would have expected faster
convergence using this BIAS method, however I am new to this feature. Is
this what I should expect ??
2) How will changing the ISOTOPE number in the MATERIAL card effect low
energy neutron propagation ?? Does it only effect nuclear parameters such
as the cross-sections, multiplicity and kinematics at higher energies ?
Thanks,
John
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