Re: [BLAST_ANAWARE] question: how to link hit detectors with particles in the mc

From: Chi Zhang (zhangchi@MIT.EDU)
Date: Tue Sep 14 2004 - 23:45:29 EDT


Hi Aaron,

if anyone has not replied with this yet.

I think this is exactly what Simon was pointing to in his message. But I
think we would be able to work arround it and the work arround I can think
of is simply turn all the physics OFF. And also turn the 200um wire
resolution OFF for sake of run time.

then a neutron will remain a neutron, never turn into two neutrons and a
gamma. Since we are going to stick in resolution by hand, instead of using
the MC data for reconstruction, energy loss, multiple scatterin, hadronic
interaction and detector resolution simply don't matter. I can't think
of any place they play a role in the new "scheme of simulation". All we
need is knowing the damn track passed through 18 wires.

Chi

On Mon, 13 Sep 2004, Aaron Joseph Maschinot wrote:

>
> in the new monte carlo formalism, a text file named 'event.dgen' will be
> generated which will include, among other things, the detectors that each
> particle in the specified reaction hits. for acceptance studies, it
> is necessary to link the hit detector information with the identity of
> the particle hitting it (else we have to use the reconstruction to do
> so, which contradicts the reason for this formalism). this sounds cut and
> dry.
>
> however, some confusion arises when particle-disintegration/transformation
> physics processes (e.g. pair production and hadronic interactions) are
> included. for example, in a LAD, it's possible that a neutron will
> transform into a neutron and a gamma, into two neutrons and a gamma, into
> a proton, an electron, and a gamma, etc.
>
> my question is this: what should be recorded to event.dgen? currently, i
> have it setup so that all detectors hit by one of the event-originating
> particles (at the target) are recorded. however, as soon as a reaction
> happens that causes GEANT to start a new track (e.g. GEANT would consider
> the two neutrons in n --> n + gamma to be separate tracks and particles),
> i stop recording.
>
> so, what is the preferred way of recording here:
>
> 1) record hits until a GEANT-recognized particle disintegration/
> transformation occurs
>
> 2) record all hits from all particles originating from any particular
> event-origin particle (thus, e.g., in d + e --> e' + p + n followed
> by n --> n + n + gamma, all detectors hit by either neutron or the
> gamma would be recorded as being hit by the original neutron)
>
> 3) record all hits from "like" particles originating from any
> particular event-origin particle (thus, e.g., in the example above in
> 2), only detectors hit by a neutron (either one), but not the gamma,
> would be recorded as being hit by the original neutron)
>
> 4) else ???
>
> aaron
>



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