[Rivet] units in Rivet

[Hannes Jung]

Dear Andy et al


so finally I found that it was indeed HepMC, which caused the problems... Rivet was working fine.

The problem was, that the HepMC version I used locally was the one which comes with the Rivet 
installation, and which is compiled with units=GeV as default. THe HepMC versions which are on
Genser are compiled with units=MeV as default (don't know, why this is.... )...
The weird thing is, that HepMC does not say anything, that it is compiled with whatever default units....

Now, with HepMC 2.06.09 there is a way to change the default units (thanks to Judith who pointed me
to various email exchanges....):

      HepMC::GenEvent* evt = hepevtio.read_next_event();
      evt->define_units( HepMC::Units::GEV, HepMC::Units::MM );
      evt->use_units(HepMC::Units::GEV, HepMC::Units::MM);

with this at least it works.... but can be used only with version > 2.06.09,
in earlier versions "define_units" is not available.

Maybe this mail helps others, not to spend as much time as I did to sort out the problem...
Sorry for complaining about HepMC on this email list....

Cheers

Hannes



On 17.08.2012, at 15:40, Andy Buckley wrote:

> Hi Hannes,
> 
> The HepMC units debacle continues! Are you reading the exact same HepMC
> events into Rivet on both machines? This would eliminate one source of
> error: dump the PYTHIA events to a file, and check what the units and
> beam energy values are in that file, then try reading the same file into
> Rivet on both machines. If there is a problem, then it sounds like we
> need to fix something... or HepMC does.
> 
> What HepMC, Rivet, etc. versions are you using?
> 
> Cheers,
> Andy
> 
> 
> On 17/08/12 14:33, Hannes Jung wrote:
>> Dear developers
>> 
>> I am stuck at the moment with a strange problem:
>> 
>> I have compiled Rivet on different machines from scratch and run it on a
>> standalone version of PYTHIA (not in AGILE).
>> On one machine the units for energy are in GeV and on the other they are
>> in TeV, although I have explicitly set it to GeV in the hepmc configure.
>> Even if I force the unit GeV in Rivet, for example by using sqrtS()/GeV,
>> on machine it is in TeV and on the other in GeV.
>> 
>> I am lost there...
>> 
>> Any idea what I could check, where things could go wrong ? 
>> 
>> Thanks a lot
>> 
>> Cheers
>> 
>> Hannes 
>> 
>> 
>> ***********************************************************************
>> Hannes Jung 
>> Email: Hannes.Jung at desy.de <mailto:Hannes.Jung at desy.de> 
>> mobile :+49 40 8998 93741
>> http://www.desy.de/~jung                                           
>> Tel: +49 (0) 40 8998 3741         
>> Fax: +49 (0) 40 8998 3093 
>> DESY, CMS 01B/02.213
>> Notkestr.85, 22603 Hamburg, FRG   
>> ***********************************************************************
>> 
>> 
>> 
>> 
>> 
>> 
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>> Rivet at projects.hepforge.org
>> http://www.hepforge.org/lists/listinfo/rivet
>> 
> 
> 
> -- 
> Dr Andy Buckley, SUPA Advanced Research Fellow
> Particle Physics Expt Group, University of Edinburgh
> 
> The University of Edinburgh is a charitable body, registered in
> Scotland, with registration number SC005336.
> 

***********************************************************************
Hannes Jung 
Email: Hannes.Jung at desy.de 
mobile :+49 40 8998 93741
http://www.desy.de/~jung                                           
Tel: +49 (0) 40 8998 3741         
Fax: +49 (0) 40 8998 3093 
DESY, CMS 01B/02.213
Notkestr.85, 22603 Hamburg, FRG   
***********************************************************************