[Halld-offline] selection of p pi+ pi-, p pi+ pi- pi0 events

[Richard Jones]

Kei,

You wrote,
|  If people could give me comments on why I don't get
|  exactly the same number of events when running with
|  different EM backgrounds, I would be grateful.

The short answer is that hdgeant appends new particles to the end of the
event Monte Carlo record (Reaction tag) depending on the secondaries that
are produced during tracking.  You cannot lose particles from the Monte
Carlo record, but you can gain more.  This can either increase or decrease
your event count in a given channel, either by moving events into the
channel by adding particles that it was missing, allowing it to satisfy the
particle counts for the channel, or by moving events out the channel by
pushing the particle counts outside the ranges required for the channel.
 EM background is very poor in hadrons, so this explains why your different
channel counts differ by only a couple dozen when you change the bg
conditions.

-Richard Jones


On Fri, Mar 14, 2014 at 12:24 PM, Kei Moriya <kmoriya at indiana.edu> wrote:

>
> I've updated the code to select specific reactions.
> The files are in
> trunk/sim-recon/src/programs/Utilities/hddm_select_events
>
> You can run on non-REST files with
> hddm_select_events -s 5 -i [input hddm] -o [output hddm]
> To run over REST files use the -r option.
> The option -s [selectType] specifies which events you
> want to select. 5 is for p pi+ pi-, 6 is for p pi+ pi- pi0.
>
> If people could give me comments on why I don't get
> exactly the same number of events when running with
> different EM backgrounds, I would be grateful.
>
>         Kei
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