The fate of particles

From: Joseph Comfort <>
Date: Fri, 28 Aug 2009 06:51:43 -0700 (MST)

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,
Received on Fri Aug 28 2009 - 17:38:50 CEST

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