Introduction

We had a Geant3 simulation for MuCap for some time. The code was in FORTRAN mainly developed by Peter K and Bernhard. Documentation:

• Original documentation by Peter
• Bernhard's webpage
• check Bernhard's MC presentation
• CVS archive

In March 2009 Peter started the development of a GEANT4 version of this program motivated by the following issues

• We need intense MC effort to study important issues in the ongoing final MuCap analysis, e.g. like the electron/muon interference.
• We need a Monte Carlo for MuSun to optimize the pad geometry and to simulate and study fusion processes and tracking.

A skeleton version has been released to CVS and Serdar will continue to develop this tool. The detector modeling and mapping to the input stream might proceed with the help of Fred, Volodya and Bernhard.

G4MuCap

Setup

Define your G4WORKDIR. Run on pion1 to have correct libraries. CVS the G4MuCap there. cd G4MuCap. source setup after adjusting it. cd $G4WORKDIR. cp -R examples from $G4INSTALL (probably not necessary but educational. Different vis drivers installed. OpenGl, DAWNFILE, HepRep, jas3+WIRED4 according to Geant Manual.

First you login to pion1 machine and from you home directory, get G4MuCap from cvs by,

yourname@pion1 ~> cvs co G4MuCap

In the pion1 machine, go to the cshell by entering,

yourname@pion1 ~> csh

at the cshell window then

yourname@pion1 ~/G4MuCap > source setup

yourname@pion1 ~/G4MuCap > gmake

Then you can run the G4 to get some events,

yourname@pion1 ~/G4MuCap > MuCap

results are saved in a zip file named such as, scene-0.heprep.zip

In order to see the output file, you will need to have jas3 downloaded from link and unzipped into the G4MuCap directory. Then in order to visualize events, You will need to get Wired4 from link where all .jar files listed there should be downloaded into your G4MuCap/jas3-0.8.3/extensions directory.

After that, in your G4MuCap directory enter

yourname@pion1 ~/G4MuCap > jas3-0.8.3/jas3 scene-0.heprep.zip or from your pion1 machine

yourname@pion1 ~> jas3-0.8.3/jas3 scene-0.heprep.zip

Once you have Jas3 window opened, It is going to ask whether you want to install new plugins, say yes and you are done.

In order to see events, on the jas3 window, click on File->New->Wired4 on you Jas3 window.

Documentation

MuCap is derived from example ExN02. cd $G4MuCap.

• gmake clean
• gmake
• MuCap
• jas3 scene-0.heprep.zip

There is a

const static G4int nSegScale=10; // scales the segmentation for easier display

in MuCapDetectorConstruction.hh to scale the real segmentation for graphic viewing. The relevant detector geometry parameters are private data member of the class and are defined in one block of code within MuCapDetectorConstruction.cc. All relevant parameters should be defined there.

Todo List

• Refine geometry (lower priority)
• Refine gun (lower priority)
• Include missing sensitive detectors
• Install some messengers for interactive change of beam parameters and switch on/of geometry elements
• Perform EndOfEvent(G4HCofThisEvent*) processing in sensitive detector to define tree of hits and MC generated information
• Identify mapping between geometry and readout
• Tune and explore performance with/without graphics
• Include hard trajecory filtering

Studies

There are several studies we want to perform. They include

Pre analysis

• Stopping distribution on individual anodes with cuts
• Electron-muon track interference
• m+p scattering (G4SingleScattering?)
• Diffusion?

Full Analysis

• Blue cont anode studies

Pictures