Re: The fate of particles

Hi Joe

Did you try tagging on the generation number (variable Ltrack in TRACKR)?
That should tell you if it is a beam particle or secondary from an
inelastic reaction. If inelastic, I would except all final state particles
to be of generation Ltrack+1, even for the diffractively scattered
particle (although for the latter not 100% sure). Also don't forget taking
weights into account when counting.

Please let me know if the problem persists.

Cheers
Stefan

On Fri, 28 Aug 2009, Joseph Comfort wrote:

> I am simulating a beam of K+ passing through degraders in a beamline and
> stopping in a target. We want to know the ultimate fate of each K+, that
> is the final process which causes it to disappear. Details about the
> daughters is not important at the moment.
>
> Regions are set up for each material element and the beamline that
> contains them. Stopped K+ are identified in (entry) MGDRAW as having zero
> momentum. K+ that decay in flight are identifed in MGDRAW/USDRAW as
> having ICODE=102 and non-zero momentum. Particles that escape from the
> beamline are identified in MGDRAW/BXDRAW as having crossed into an
> external region. The distributions of results look good and respond to
> changes in degrader materials and momentum about as expected.
>
> However, the total number of such events comes up short. There are, of
> course, nuclear interactions (e.g., ICODE=101). I am just a little unsure
> how to handle them. Some inelastic processes can produce additional
> particles while leaving the K+ for more tracking, and hence possible
> double counting. In others, the K+ disappears in a reaction. How are
> these cases distinguished. Does a list of secondaries have to be
> checked? In addition, are there other processes (code numbers) where a
> K+ disappears and would not be counted?
>
> Thank you,
> Joe
>
>

-- 
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Stefan Roesler
CERN, DG-SCR
CH-1211 Geneva 23
Switzerland
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