h1. Software Hints and Tips

h2. Running a tracker simulation

There is a dedicated directory holding top level scripts for producing tracker data within MAUS at:

<pre>

bin/user/scifi

</pre>

For example to run a MAUS simulation of the tracker in the presence of a magnetic field do the following from the MAUS root directory:

<pre>

source env.sh

cd bin/user/scifi

./simulate_scifi.py --configuration_file datacard_mc_helical

</pre> 

The equivalent command for no magnetic field (straight tracks) is:

<pre>

./simulate_scifi.py --configuration_file datacard_mc_straight

</pre>

h2. Datacard variables

Datacard variables control the various parameters passed to MAUS. The variables assume the default values set in src/common_py/ConfigurationDefaults.py unless overridden in a datacard or elsewhere.  Here are a few common variables: 

* Number of spills. The number of spills to simulate can be set by editing the relevant datacard file and changing the variable 'spill_generator_number_of_spills'.

* The number of particles per spill is controlled by the beam variable. This has a number of sub-variables, two of which can be set to alter the number of particles per spill:

** 'binomial_n' is the number of attempts at generating a track

** 'binomial_p' is the probability an attempt succeeds

* Helical pattern recognition can be turned on or off by setting 'SciFiHelicalPROn' to 1 or 0 respectively

* Straight pattern recognition can be turned on or off by setting 'SciFiStraightPROn' to 1 or 0 respectively

h2. Accessing the output data

Data is output by MAUS either as "ROOT":http://http://root.cern.ch/ or JSON documents.  In order for ROOT to understand the classes we have written a ROOT dictionary, built automatically by MAUS must first be loaded. In an interactive ROOT session this done with following command:

<pre>

.L $MAUS_ROOT_DIR/build/libMausCpp.so

</pre>

The equivalent command if using "PyROOT":http://root.cern.ch/drupal/content/pyroot is 

<pre>

import libMausCpp

</pre>

An example ROOT session to open a data file would be:

<pre>

> .L $MAUS_ROOT_DIR/build/libMausCpp.so

> TFile f1("maus_output.root")

> TBrowser b

</pre>

The equivalent PyROOT session would be:

<pre>

> from ROOT import *

> import libMausCpp

> f1 = TFile("maus_output.root")

> b = TBrowser()

</pre>

The tracker MC data can then be found by browsing to:

<pre>

Spill:data:_spill:_mc:_sci_fi_hits

</pre>

The reconstructed data is stored under:

<pre>

Spill:data:_spill:recon:_scifi_event

</pre>