Electron fluence unexplained edges

From: George Kharashvili <georgek_at_jlab.org>
Date: Thu, 19 Aug 2010 17:40:53 -0400 (EDT)

Dear FLUKA experts,

We modeled interaction of 1-GeV electrons with a 5-cm radius, 10-cm long
cylindrical gold target (FLUKA input file attached "primaries.inp").
Electron fluence in the target region is scored using USRTRACK card in
1000 bins between 8 MeV (which is also e-/e+/photon energy cutoff set using
EMFCUT card ) and 1 GeV. The electron spectrum displays unexplained (to
us) edges at approximately 50, 110, 210, 390, 700 MeV. You can see this in
"allE.eps"; file in the attachment. Can these edges be explained?

When we scored just the primary particles using USRTRACK and
AUXSCORE (BEAMPART option) there were no edges and no electrons scored
below approximately 490 MeV (primaries_beampart.eps). Is this also strange?
In order to track down where these edges were coming from, we modified a
user subroutine fluscw.f to distinguish between 1st, 2nd, 3rd, and 4th
generation electrons ("llofluscw.f"). New input file is "llo.inp".
Fluences of all 4 different generations of electrons are plotted in
"llo_Efluences.eps". The edges are present in all 4 cases and
also the first generation electron fluence is different from the
fluence scored using AUXSCORE BEAMPART. Is BEAMPART different from first
generation particles defined by LLO=1? (Using LTRACK instead of LLO
didn&#8217;t change anything).

I should also mention that turning off Bhabha/Moller scattering
did not affect the edges and made almost no difference in case of 2nd,
3rd and 4th. However, 1st generation electron fluence decreased noticeably
between 0.940 MeV and 970 MeV.

So the three main questions are:
1. What is the reason for the edges in electron spectrum?
2. What is the difference betweenBEAMPART and LLO=1?
3. Why is the BEAMPART spectrum equal to 0 below 490 MeV?

Thank you,

  - George

Received on Sat Aug 21 2010 - 00:15:22 CEST

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