View source for SctparSim (PAPAS)

== About papas, heppy et cetra ==

Particle propagation is done by geometry calculation.
To valid the calculation several different cases were plotted.

[[File:Tof_test_9k.png|thumb|center|alt=Helix.|Helix.]]

== Configure detector parameters ==

The detector parameters can be changed via a configuration file ''CTauPapas.cfg'' placed in the main papas simulation folder.
The file has a simple structure --- one parameter and its value(s) per line.
A parameter's name and value(s) should be separated by spaces.
Empty lines and lines beginning with # are ignored.

In the example below the parameter at the first line is one number,
while the parameter at the second line is an array.

<code>
ecal_emin_barrel 0.05

ecal_eres 1.34e-2 0.066e-2 0 0.82e-2
</code>

The parameters can be given in any order.


== Configure detector parameters ==

The file ''ctau_input_sim.txt'' contains two lines.
The first line is the path to a primary simulation file (see [[MC_Data_Sets|MC Data Sets]] page).
The second line is an integer number of events to be processed.


== How to run papas ==

Copy a directory with papas on stark the machine and go to this directory.

<code>
cd

cp -rf ~razuvaev/myheppy .

cd myheppy
</code>

There are a directory ''output'' for output files,
detector configuration file ''CTauPapas.cfg'',
file ''ctau_input_sim.txt'' with a path to the file with primary generator events,
and the folder ''heppy'' with heppy code itself.
Let's go into it and tune environment.

<code>
cd heppy

source init.sh
</code>

Now it is time to run papas.
You may be asked a question because the output directory is not empty.
So just input <code>y</code> or clean the folder.

<code>
cd test

./heppy_loop.py ../../output/ ctau_cfg1.py
</code>

If it don't want to run try <code>source ~razuvaev/.bashrc</code> and <code>source ../init.sh</code> because it can be caused by the problem with environment variables.

When papas simulation has been done one need to present papas output to a suitable form and also add initial generator information.

<code>
cd ../../

./txt2tree.py
</code>

The output root tree is available in the file ''myheppy/output/txt2tree.root''.

== Output tree ==

The output tree contains branches which can be divided in several groups:
* reconstructed particle parameters;
* generated particle parameters;
* generated vertices;
* connection between reconstructed particles, generated particles and generated vertices.

The table below presents branches and description of their content.
{| class="wikitable"
|-
! Name
! Type
! Length
! Description
|-
| colspan="4" style="text-align: center;" | Reconstructed particles
|-
| n
| int
| 1
| The number of reconstructed particles.
|-
| px
| float []
| n
| The reconstructed particle momentum: x coordinate.
|-
| py
| float []
| n
| The reconstructed particle momentum: y coordinate.
|-
| pz
| float []
| n
| The reconstructed particle momentum: z coordinate.
|-
| colspan="4" style="text-align: center;" | Generated particles
|-
| n0
| int
| 1
| The number of generated particles.
|-
| px0
| float []
| n0
| The generated particle momentum: x coordinate.
|-
| py0
| float []
| n0
| The generated particle momentum: y coordinate.
|-
| pz0
| float []
| n0
| The generated particle momentum: z coordinate.
|-
| colspan="4" style="text-align: center;" | Generated vertices
|-
| nv0
| int
| 1
| The number of generated vertices.
|-
| vx0
| float []
| nv0
| The generated vertex: x coordinate.
|-
| vy0
| float []
| nv0
| The generated vertex: y coordinate.
|-
| vz0
| float []
| nv0
| The generated vertex: z coordinate.
|-
| colspan="4" style="text-align: center;" | Links
|-
| recgen
| int []
| n
| Transform a reconstructed particle index to the generated particle index.
|-
| genver
| int []
| n0
| Transform a generated particle index to the generated vertex index.
|}

== Analysis example ==

Here a short analysis example of
<math>D^0 \to K_S^0 \pi^+ \pi^-</math>
is presented.
The things are performed with PyROOT.

The data a taken from the available
[[MC_Data_Sets#Exclusive_samples|exclusive sample]].

The code can be taken from github
[https://github.com/lbrl/sctau_py/blob/master/search_dkspipi.py]
or find at the stark cluster: 
''/home/razuvaev/myheppy/search_dkspipi.py''.

<gallery>
File:Dkspipi_mksmd0.png|alt=mksmd0.|<math>K_S^0</math> mass vs <math>D^0</math> mass.
File:Dkspipi_md0pd0.png|alt=md0pd0.|<math>D^0</math> mass vs its momentum.
</gallery>