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 

h2. Accessing the output data

Data is output by MAUS either as ROOT 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 the be found by browsing to