| META TOPICPARENT |
name="TrackerSoftware" |
In the following we will generate manually a 'single proton' event, which can be fed into OSCAR and ORCA.
The HEPEVT ntuple structure
OSCAR expects its input in an HBOOK ntuple with the following fields:
Block HEPEVT:
integer NEVHEP = event number
integer NHEP = number of entries (particles, partons)
integer ISTHEP(NHEP) = status code
integer IDHEP(NHEP) = PDG identifier
integer JMOHEP(2,NHEP) = position of 1st and 2nd mother
integer JDAHEP(2,NHEP) = position of 1st and last daughter
real PHEP(5,NHEP) = 4-momentum and mass (single precision in ntuple file)
real VHEP(4,NHEP) = vertex xyz and production time (single precision in ntuple file)
Block MC_PARAM:
integer IRNMCP = run number
integer IEVMCP = event number
real WGTMCP = event weight
real XSECN = cross section equivalent
integer IFILTER = filter pattern
integer NVRMCP = number of additional variables
real VARMCP(NMXMCP) = list of additional variables
Writing ntuples
Writing such an ntuple is straightforward in Fortran [TODO: C/C++ interface via cfortran.h], see the attached example program.
- Define the data blocks as Fortran COMMON's.
- Create an ntuple with the
HROPEN procedure (say test.ntpl), and define its structure with HBNAME. Note: ntuple's ID must be 100 (unpacked) or 101 (packed; a bit tricky)
- Do a loop over the events, generate some particles, etc; at the end of the loop
call hfnt(ID)
- Close the ntuple.
Compile the program with g77 -c test.f and link with g77 -o test.run test.o `cernlib packlib,mathlib`
This requires a running g77 system with cernlib properly installed (on debian: apt-get install cernlib)
Run the executable.
Now the file test.ntpl should contain the particles. You can test it by opening with PAW:
h/file 0 test.ntpl 4096
n/print 100
n/plot 100.idhep
TODO: this example program does not call Pythia to decay instable particles, but who cares anyway? We want now to control everything manually.
Feed into OSCAR
This note assumes that you have a properly installed OSCAR environment.
Copy or symlink test.ntpl into the OSCAR working directory (in my case, it's OSCAR_3_9_9/src/Workspace).
Edit oscarrc:
...
OutputDataSet = /System/sim/test
EventNtplReader:NtplFileName = test.ntpl
EventNtplReader:NtplID = 100
...
Do the ritual eval `scram run -sh` (or -csh), and run oscar -c oscarrc
This will produce a lot of sim and xml files (see ProduceSimulatedEvents)
Further readings
CMKIN
HBOOK Reference
-- GergelyPatay - 08 Mar 2006 | 
