\page ExampleHadr00 Example Hadr00

\author V.Ivanchenko \n
CERN, Geneva, Switzerland

This example demonstrates a usage of G4PhysListFactory to build 
Physics List and G4HadronicProcessStore to access cross sections.

## GEOMETRY

The Target volume is a cylinder placed inside the World volume. Following 
UI commands are available to modify the geometry:

```
/testhadr/TargetMat     G4_Pb
/testhadr/WorldMat      G4_AIR
/testhadr/TargetRadius  10 mm
/testhadr/TargetLength  20 cm
```

By default beam direction coincides with the target axis and is Z axis 
in the global coordinate system. The beam starts in the middle of the target.
G4ParticleGun is used as a primary generator. The energy and the type of 
the beam can be defined via standard UI commands

```
/gun/energy   15 GeV
/gun/particle proton
```

## PHYSICS

Physics List is defined by its name given in the 3d argument of the of the 
run command. 

```
./Hadr00 my.macro QGSP_BERT 
```

If 3d argument is not set then by the PHYSLIST environment variable. 
By default FTFP_BERT Physics List will be instantiated.
 
## CROSS SECTION

At the end of any run the set of cross sections is built and can be printed 
out for a given projectile particle and a target element, which can be 
defined via UI commands:

```
/testhadr/particle   pi+
/testhadr/targetElm  Pb
/testhadr/verbose    1
```

The level verbosity above zero provides printout of the cross section table.
The energy/momentum limits and number of bins can be set via UI commands:

```
/testhadr/nBinsE      900
/testhadr/nBinsP      700
/testhadr/minEnergy   1 keV
/testhadr/maxEnergy   1 TeV
/testhadr/minMomentum 1 MeV
/testhadr/maxMOmentum 10 TeV
```

## VISUALIZATION

The vis.mac file can be used as an example of visualization. 

## HISTOGRAMS

All histograms are provided in decimal logarithmic scale (log10(E/MeV)
and log10(p/GeV)) for one projectile particle and one target element.
The element is taken from the Geant4 NIST database, natural isotope 
composition is assumed. 

Only ROOT histograms are available.