Re: Disabling MCS

From: Anna Ferrari <>
Date: Sun, 16 Jan 2011 01:30:47 +0100 (CET)

Dear Daniel,

probably you are suppressing multiple scattering but is not this message
that tells you this. This message in my opinion says only that the Moliere
theory of the scattering is used, for primaries and secondaries, thing
that is true even if you set the parameters to completely suppress,
practically, the MCS (somebody can eventually correct me!)

In particular:
- if you use your second method (MCSTHRES card) you don't "swich off" the
multiple scattering, you practically suppress it by setting a minimum
threshold bigger that the beam energy.
- if you use the MULSOPT card you have also to specify (in what(4) and
what(5)) the interval of material indices where the complete suppression
of the multiple scattering that you have set is valid. If you have done
this (I think yes) in the output file you should find, for each medium
where the MCS suppression is activated, the message:

   *** Multiple scattering not performed for this medium ***

I think you have to check this.

Hope it helps,


> Hello all,
> I want to disable multiple coulomb scattering to do some tests to my
> simulation
> and I'm getting some weird results.
> I've done it both with MULSOPT card (by setting WHAT(2) and WHAT(3) to
> 3.0)
> and with MCSTHRES with a negative value higher in absolute value than the
> beam energy. Both give similar results.
> I won't discuss here the physics of the problem until I've analysed it
> myself
> carefully, however, the output file will always show the following
> message,
> regardless if the MCS is turned on or off:
> Moliere Coulomb scattering for primaries: T
> Moliere Coulomb scattering for secondaries: T
> Hadrons/muons:
> Flag for MCS check with boundary normals: F
> Flag for Coulomb single scattering(s) at boundaries: F
> (# of Coulomb single scattering(s) at boundaries: 1)
> Flag for single scatterings below min. (Moliere) energy: F
> Should I regard it as a bug in the output, or is MCS still on somehow?
> Daniel Sanchez Parcerisa
> PARTNER Early Stage Researcher
> Siemens AG
Received on Sun Jan 16 2011 - 13:13:04 CET

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