[fluka-discuss]: What particle crosses a boundary

From: Joseph Comfort <Joseph.Comfort_at_asu.edu>
Date: Sat, 1 Mar 2014 16:23:05 -0700 (MST)

I sometimes use boundary crossings as a means to identify the particle
that reached a boundary (detector). There are some problems.

The setup is very simple: A line beam of 1-GeV/c particles travel 2000 cm
in vacuum before hitting a square 'target'. The target has either copper
or vacuum. Mgdraw is used to select on particle crossings from the
vacuum _into_ the target, and each particle type is recorded.

100,000 pi+ beam on 1-cm-thick copper: 72,835 particles enter the target.
That is OK. In addition to pi+, mu+, and 2 e+, there are 9 photons and 5
pi-. How can pi+ decays produce photons and pi- in vacuum? (The vacuum
target gives only pi+ and mu+.)

1 million K0Long beam on 5-cm-thick copper: 542,355 particles enter the
target. They include e-, e+, gamma, mu+, mu-, K0, and K0bar (also true
for vacuum target). But there are also 26 protons and 38 neutrons!
How can a K0L produce a p or n in vacuum?

It appears that JTRACK does not identify the particle that hit and crossed
the boundary, but rather something after interactions somewhere in the
medium. In the case of several produced particles, which one is chosen?

How can the particle that hit the boundary be identified?

Joe Comfort
Received on Sun Mar 02 2014 - 01:27:57 CET

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