Software Hints and Tips¶

Running a tracker simulation¶

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

bin/user/scifi

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:

source env.sh
cd bin/user/scifi
./simulate_scifi.py --configuration_file datacard_mc_helical

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

./simulate_scifi.py --configuration_file datacard_mc_straight

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

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:

.L $MAUS_ROOT_DIR/build/libMausCpp.so

The equivalent command if using PyROOT is

import libMausCpp

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

> .L $MAUS_ROOT_DIR/build/libMausCpp.so
> TFile f1("maus_output.root")
> TBrowser b

The equivalent PyROOT session would be:

>>> from ROOT import *
>>> import libMausCpp
>>> f1 = TFile("maus_output.root")
>>> b = TBrowser()

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

Spill:data:_spill:_mc:_sci_fi_hits

The reconstructed data is stored under:

Spill:data:_spill:recon:_scifi_event

An example PyROOT session to access some data:

>>> from ROOT import *
>>> import libMausCpp
>>> f1 = TFile("maus_output.root")
>>> t1 = f1.Get("Spill")
>>> t1
<ROOT.TTree object ("Spill") at 0x8bfa970>
>>> data = MAUS.Data()
>>> t1.SetBranchAddress("data", data)
>>> t1.GetEntry(1)
51435
>>> spill = data.GetSpill()
>>> spill
<ROOT.MAUS::Spill object at 0x92f4a40>
>>> spill.GetReconEvents().size()
1L
>>> revt = spill.GetReconEvents()[0]
>>> sfevt = revt.GetSciFiEvent()
>>> sfevt
<ROOT.MAUS::SciFiEvent object at 0x9310cb0>
>>> htrks = sfevt.helicalprtracks()
>>> htrks.size()
2L
>>> seeds = htrks[0].get_spacepoints()
>>> seeds.size()
5L
>>> sp = seeds[0]
>>> sp.get_position().x()
8.468833333333333
>>>