Re: transport cut-offs in selected regions

From: Francesco Cerutti <>
Date: Sat, 28 Aug 2010 19:21:08 +0200


I would like just to add some warnings with respect to the powerful recipe
suggested by Giuseppe, intended to *increase* on a material/region basis
the transport thresholds set in the input file. As he explained, zeroing
its weight below the desired energy means killing the particle and so
saving CPU time. But, contrary to what happens when the cutoff is reached,
the remaining energy is lost, and no ranging out is performed for charged
particles (so *local* energy deposition and tracklength scoring is
jeopardized). On the other hand, changing the particle energy in order to
bring it below the general threshold (not recommended), does not prevent
the standard end of transport treatment, which however becomes a nonsense

Francesco Cerutti
CH-1211 Geneva 23
tel. ++41 22 7678962
fax ++41 22 7668854

On Sat, 28 Aug 2010, John Clem wrote:

> Hi Giuseppe, the primary objective is cpu time reduction for the run..
> It is my understanding, a particle assigned no weight (WEE=0) will
> continue to be tracked irregardless and subject to all physical
> mechanisms that were set in the input controls. I assume it is not
> possible to set Eksco=0 in usrmed.f ??
> Thanks, John
> G. Battistoni wrote:
>> Hi John
>> the way to accomplish your task is to make use of the "usrmed.f" user
>> routine.
>> You activate the call to usrmed by means of the command MAT-PROP with
>> SDUM=USERDIRE for a series of different selected materials (see the manual for
>> essential details).
>> Now, if you look at usrmed.f you see that you have available the
>> following variables:
>> * ij = particle id
>> * Eksco = particle kinetic energy (GeV)
>> * Pla = particle momentum (GeV/c)
>> * Wee = particle weight
>> * Mreg = (original) region number
>> * Newreg = (final) region number
>> Therefore you can set up a logic so check Eksco for a given particle
>> when it is within region Newreg (usrmed will be called at each step, but
>> you can also
>> implement a logic at the passage from Mreg to Newreg, if this helps you).
>> As soon as you want to cut it out below a given
>> threshold, you must simply set (in the same routine)
>> In summary, by means of MAT-PROP and usrmed.f
>> you can exploit a check as a function of both materials and regions.
>> Giuseppe
>> John Clem wrote:
>>> Hi All,
>>> As we know the "EMFCUT" command allows the option to set the electron
>>> and photon energy transport cut-offs in selected regions. This identical
>>> option for hadrons and muons would also be very useful in some
>>> applications, however it is my understanding the "PART-THRes" command is
>>> not region dependent. Is there a means to set the energy transport
>>> cutoff for muons and hadrons for selective regions (or materials)?
>>> Thanks, John Clem
> --
> >>John Clem
> >>Research Associate Professor
> >>Bartol Research Institute
> >>Department of Physics and Astronomy
> >>University of Delaware
> >>Newark, DE 19716
> >>off 302-831-4354
> >>cell 302-388-1218
Received on Sat Aug 28 2010 - 19:59:47 CEST

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