Bad FastSimEvent dependency in reco-ntuple.

[rovere]

I'm not sure why we had to reuse FastSimulation tools inside the reco-ntuple.
Inspired by the problem Jeremy reported last Monday, I discovered that the FastSimEvent does implicitly make assumptions (hardcoded, of course) on the geometry that are indeed false and meaningless for the HGCAL case.
I'm, in particular, referring to these values that are required from here. This confuses the ntuplizer that will simply skip valid simTracks for no good reasons.
And no, of course they are not configurable.

[clelange]

The use of these tools was introduced by @beaudett since he already knew how to use these tools. Given the issues you point out, I agree that this should be fixed.

[rovere]

We could either customize the tool in the official release or find some alternative which, admittedly, will require time.
I'm not familiar with the kind of tools that FastSimEvent provided out of the box that we are using in the ntuplizer. Maybe some hits/guidance from @beaudett (et all, of course), would help and speed up the process.

[beaudett]

Hello, I had introduced the FSimEvent in the code as it carries out a rather non-trivial task out of the box. Indeed, it is able to connect together the multiplies particles created by Geant4. For example, in the default SimTrack collection, when an electron emits a Brem, both the outgoing electron and the incoming electrons as well as the photon are recorded as different particles. With the FSimEvent one gets just one electron and the different photons. Therefore, it directly corresponds to the information that we want to store. The alternative is to use the TrackingParticles but I hadn't the necessary knowledge to do so, and as far as I know, it is less user-friendly. Now, the hard-coded values are indeed annoying. My favourite solution would be to fix it in the release, introducing the two parameters https://github.com/cms-sw/cmssw/blob/master/FastSimulation/Event/src/KineParticleFilter.cc#L22-L24 in the corresponding configuration file: https://github.com/cms-sw/cmssw/blob/master/FastSimulation/Event/python/ParticleFilter_cfi.py that is imported in the ntuplizer configuration file. I can take care of implementing this change once I am back from vacation, i.e. next week. Florian

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On 29/08/18 17:30, Marco Rovere wrote: We could either customize the tool in the official release or find some alternative which, admittedly, will require time. I'm not familiar with the kind of tools that FastSimEvent provided out of the box that we are using in the ntuplizer. Maybe some hits/guidance from @beaudett <https://github.com/beaudett> (et all, of course), would help and speed up the process. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#60 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AEV5U6UeIT8RO97s1RPixmoxZr-xGLNwks5uVrOwgaJpZM4WRvTY>.

[rovere]

Ciao @beaudett ,
this kind of logic ("clever" event analysis) is what I have re-implemented with graphs in the CaloParticles. I'm not sure if we could rely completely on that and, also, if those (the CaloParticles) are covering all the use cases we envisage to study with the ntuplizer.
For the time being, I agree with your suggestions and improve the code in the release.
Thanks for the insight.

[beaudett]

FYI:
cms-sw/cmssw#24473

[clelange]

Hello @beaudett and @rovere - now that cms-sw/cmssw#24473 is merged (and is in CMSSW_10_3_0_pre5), would you be willing to change the ntupliser configuration/code such that it uses values that make sense?

[beaudett]

Hello @clelange ,
ok, I'll do it. Since I understood you are working on an updated version, is it fine if I provide you with the two python lines that will go in the config file so that you directly include it in your version ?
F.

[clelange]

Sure, that would be fine.

[beaudett]

So, I propose to put
process.ana.TestParticleFilter.rMax = cms.double(160.)
process.ana.TestParticleFilter.zMax = cms.double(319.)

The first one is consistent with what is done in the ntuplizer code. The second one should correspond to a position located after the thermal shield. The position of the first silicon layer is 321cm. I don't think we need to be super-precise here.
Thanks.