Example Hadr04

This example is focused on neutronHP physics, especially neutron transport, including thermal scattering. See A.R. Garcia, E. Mendoza, D. Cano-Ott presentation at G4 Hadronic group meeting (04/2013) and note on G4NeutronHP package

MATERIALS AND GEOMETRY DEFINITION

It is a single box representing a 'quasi infinite' homogeneous medium. Two parameters define the geometry :

• the material of the box,
• the (full) size of the box.

The default geometry (1 m3 of pressurized water) is built in DetectorConstruction, but the above parameters can be changed interactively via commands defined in DetectorMessenger.

A function, and its associated UI command, allows to build a material directly from a single isotope.

To be identified by the ThermalScattering module, the elements composing a material must have a specific name (see G4NeutronHPThermalScatteringNames.cc) Examples of such materials are build in DetectorConstruction.

PHYSICS LIST

Only processes of neutronHP package are registered : neutronElastic (including thermalScattering), neutronInelastic, nCapture; nFission. See class NeutronHPphysics. No other hadronic nor electromagnetic processes.

A command allows to select or not ThermalScattering model.

Several hadronic physics options are controlled by environment variables. To select them, see Hadr04.cc

NB. class NeutronHPphysics can be reused with other physicsConstructors, as neutron processes are deleted before to be re-created.

AN EVENT : THE PRIMARY GENERATOR

The primary kinematic is a single particle randomly shooted at the centre of the box. The type of the particle and its energy are set in PrimaryGeneratorAction (neutron 2 MeV), and can be changed via the G4 build-in commands of ParticleGun class (see the macros provided with this example).

PHYSICS

All secondaries are killed in StackingAction. Therefore an event consists of the transport of the primary neutron. Then one survey the thermal and non thermal part of this parcours.

HISTOGRAMS

The test contains 7 built-in 1D histograms, which are managed by G4AnalysisManager and its Messenger. The histos can be individually activated with the command : /analysis/h1/set id nbBins valMin valMax unit where unit is the desired unit for the histo (MeV or keV, etc..) (see the macros xxxx.mac).

• 1 "incident neutron: nb of collisions above 1 eV"
• 2 "incident neutron: total track length above 1 eV"
• 3 "incident neutron: time of flight above 1 eV"
• 4 "incident neutron: nb of collisions below 1 eV"
• 5 "incident neutron: total track length below 1*eV"
• 6 "incident neutron: time of flight below 1 eV"
• 7 "incident neutron: energy distribution below 1*eV"
  

The histograms are managed by the HistoManager class and its Messenger. The histos can be individually activated with the command :

/analysis/h1/set id nbBins  valMin valMax unit 

where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)

One can control the name of the histograms file with the command:

/analysis/setFileName  name  (default Hadr04)

It is possible to choose the format of the histogram file : root (default), xml, csv, by using namespace in HistoManager.hh

It is also possible to print selected histograms on an ascii file:

/analysis/h1/setAscii id

All selected histos will be written on a file name.ascii (default Hadr04)

VISUALIZATION

The Visualization Manager is set in the main(). The initialisation of the drawing is done via the commands /vis/... in the macro vis.mac. To get visualisation:

> /control/execute vis.mac

The detector has a default view which is a longitudinal view of the box. The tracks are drawn at the end of event, and erased at the end of run.

HOW TO START ?

Execute Hadr04 in 'batch' mode from macro files :

% Hadr04   run01.mac

Execute Hadr04 in 'interactive mode' with visualization :

% Hadr04
Idle> control/execute vis.mac
 ....
 Idle> type your commands
 ....
 Idle> exit

Macros provided in this example:

• graphite.mac: neutron (2 MeV) in graphite
• run01.mac: neutron (2 MeV) in Water_ts

Macros to be run interactively:

• debug.mac: neutron (2 MeV) in Water_ts
• vis.mac: To activate visualization